Regulation and testing of vaccines‡

Abstract

Vaccines are a unique class of pharmaceutical products that meet the statutory definitions of both a drug and a biological product. 1, 2 The Food, Drug, and Cosmetic Act (FD&C Act) defines drugs, in part, by their intended use as “articles intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease”. 2 Prophylactic vaccines differ from many other drugs and biologicals primarily in the way they are administered to a large population (in particular, populations of young healthy people to prevent rather than to treat disease), in their mechanism of action, and in their risk-to-benefit profile. Although subject to the same regulations as other biological products, vaccines are inherently more difficult to develop, characterize, and manufacture than most pharmaceutical products. Current US-licensed vaccines are listed in Tables 73-1 and 73-2 . Table 73-1 Bacterial Vaccines Currently Licensed in the United States as of April 2012 Vaccine Manufacturer* Anthrax vaccine, adsorbed 6 Bacille Calmette-Guérin (BCG) vaccine 11 Diphtheria and tetanus toxoids adsorbed 1 Diphtheria and tetanus toxoids and acellular pertussis vaccine, adsorbed 1†, 2, 7 Diphtheria and tetanus toxoids and acellular pertussis vaccine adsorbed, hepatitis B (recombinant) and inactivated poliovirus vaccine combined 7 Diphtheria and tetanus toxoids and acellular pertussis adsorbed and inactivated poliovirus vaccine 7 Diphtheria and tetanus toxoids and acellular pertussis adsorbed, inactivated Poliovirus and Haemophilus b conjugate (tetanus toxoid conjugate) vaccine 2 Tetanus and diphtheria toxoids, adsorbed 4 Tetanus and diphtheria toxoids, adsorbed for adult use 1 Tetanus toxoid 1 Tetanus toxoid, adsorbed 1 Tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine, adsorbed 2, 7 Haemophilus b conjugate vaccine (meningococcal protein conjugate) 5 Haemophilus b conjugate vaccine (meningococcal protein conjugate) and hepatitis B (recombinant) vaccine 5 Haemophilus b conjugate vaccine (tetanus toxoid conjugate) 7, 8 Meningococcal (groups A, C, Y, and W-135) oligosaccharide diphtheria CRM197 conjugate vaccine 10 Meningococcal polysaccharide vaccine, groups A, C, Y, W135 combined 1 Meningococcal polysaccharide (serogroups A, C, Y and W-135) diphtheria toxoid conjugate vaccine 1 Pneumococcal vaccine, polyvalent 5 Pneumococcal 7-valent conjugate vaccine (diphtheria CRM197 protein) 3 Pneumococcal 13-valent conjugate vaccine (diphtheria CRM197 protein) 3 Typhoid vaccine, live oral, Ty21a 9 Typhoid Vi polysaccharide vaccine 8 1, Sanofi Pasteur, Inc.; 2, Sanofi Pasteur, Ltd.; 3, Wyeth, a subsidiary of Pfizer; 4, Massachusetts Public Health Biological Laboratories; 5, Merck & Co., Inc.; 6, Emergent Biodefense Operations Lansing, Inc.; 7, GlaxoSmithKline Biologicals; 8, Sanofi Pasteur S.A.; 9, Berna Biotech; 10, Novartis Vaccines and Diagnostics, Inc.; 11, Organon Teknika Corporation LLC. † License for the pertussis component of this product is held by the Research Foundation for Microbial Diseases of Osaka University (Aventis Pasteur Laboratories, Inc.). Table 73-2 Viral Vaccines Currently Licensed in the United States as of April 2012 Vaccine Manufacturer* Adenovirus type 4 and type 7 vaccine, live, oral 5 Diphtheria and tetanus toxoids and acellular pertussis vaccine adsorbed,Hepatitis B (recombinant) and inactivated poliovirus vaccine combined 7 Hepatitis A vaccine, inactivated 4, 7 Hepatitis B vaccine, recombinant 4, 7 Hepatitis A vaccine, inactivated and hepatitis B (recombinant) vaccine 7 Haemophilus b conjugate vaccine (meningococcal protein conjugate) and hepatitis B recombinant vaccine 4 Human papillomavirus (types 6, 11, 16, 18) recombinant vaccine 4 Human papillomavirus bivalent (types 16 and 18) vaccine, recombinant 7 Influenza virus vaccine 1, 3, 7, 9, 11 Influenza A (H1N1) 2009 monovalent 1, 3, 9, 10, 11 Influenza virus vaccine, H5N1 (for National Stockpile) 1 Influenza vaccine live, quadrivalent, intranasal 10 Influenza vaccine live, intranasal 10 Japanese encephalitis vaccine, inactivated 8 Japanese encephalitis vaccine, inactivated, adsorbed 12 Measles virus vaccine, live 4 Measles, mumps, and rubella vaccine, live 4 Measles, mumps, rubella and varicella virus vaccine, live 4 Poliovirus vaccine inactivated, human diploid cell 2† Poliovirus vaccine inactivated, monkey kidney cell 6 Rabies vaccine 3, 6 Rotavirus vaccine, live, oral 7 Rotavirus vaccine, live, oral, pentavalent 4 Rubella virus vaccine, live 4 Smallpox (vaccinia) vaccine, live 13 Varicella virus vaccine live 4 Yellow fever vaccine 1 Zoster vaccine, live 4 1, Sanofi Pasteur, Inc.; 2, Sanofi Pasteur, Ltd.; 3, Novartis Vaccines and Diagnostics Ltd.; 4, Merck & Co., Inc.; 5, Barr Labs, Inc.; 6, Sanofi Pasteur S.A.; 7, GlaxoSmithKline Biologicals; 8, Research Foundation for Microbial Diseases of Osaka University; 9, ID Biomedical Corporation of Quebec; 10, MedImmune Vaccines, Inc.; 11, CSL, Ltd.; 12, Intercell Biomedical; 13, Sanofi Pasteur Biologics. * These are the names of the license holders. Company names may be different. † Not available in the United States. Immunization is a major component of global and public health. Use of vaccines has resulted in the prevention of millions of deaths and cases of morbidity annually caused by infectious diseases around the world. Because vaccines are so widely used globally, it is imperative that these products be as safe and effective as current technology will permit. The assessment, licensure, control, and surveillance of vaccines are major challenges for national regulatory authorities (NRAs), who are confronted by a steadily increasing number of novel products, complex quality concerns, and new technical issues arising from rapid scientific advances. Furthermore, with emerging global markets, the volume of vaccines crossing international borders continues to increase, and it is critical that regulatory knowledge of and experience with vaccines be shared, and that approaches to their control be harmonized to the greatest extent possible. The need for a strong national regulatory authority, especially for the regulation of vaccines, is recognized worldwide. Developed countries have established governmental regulatory agencies to review and determine the safety and effectiveness of vaccines; however, even today, many developing countries do not have established NRAs. Although not an NRA, the World Health Organization (WHO) uses a consultative approach involving its Expert Committee on Biological Standardization and Biologicals Unit to develop regulatory criteria and identify and consolidate current consensus opinions on key regulatory issues. WHO also communicates to national authorities and manufacturers through guidance documents addressing both general issues and specific products.* Through this mechanism, NRAs are informed of the scientific background needed to assess critical issues, and are advised on which regulatory approaches and methodologies have been found to be optimal for ensuring the global supply of uniformly safe and effective vaccines of the highest quality. 3 The Center for Biologics Evaluation and Research (CBER) of the US Food and Drug Administration (FDA) is the national regulatory authority in the United States charged with ensuring the safety, purity, and effectiveness of vaccines in the United States. The review of vaccine applications occurs among CBER's Office of Vaccines Research and Review, Office of Compliance and Biologics Quality, and Office of Biostatistics and Epidemiology. The development of vaccines is an intricate process, and every step in the life cycle from testing of materials used for production to postlicensure lot-release testing is subject to stringent oversight by CBER. After licensure, CBER continues to oversee the production and performance of vaccines to ensure their continued safety and efficacy. The FDA/CBER regulatory review staff consists of an internal multidisciplinary team of scientists, and regulatory and public health professionals who are involved in continued exchange of information with the outside scientific community through laboratory research and collaborations, participation in workshops, seminars, and international conferences. The FDA also relies on the expertise of formal advisory committees, which include experts in the fields of vaccinology, microbiology, infectious diseases, immunology, biostatistics, epidemiology, and clinical trial design. These external expert committees review summary documents prepared by the FDA and sponsors and make recommendations on product development, safety, and efficacy. In addition, CBER works closely with its counterparts in other US governmental agencies in the Department of Health and Human Services (DHHS) and the US Public Health Service (PHS), such as the National Vaccine Program Office (NVPO), the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the Health Resources and Services Administration (HRSA). The CDC is responsible for, among other things, epidemiologic surveillance of disease and support of immunization programs. Its Advisory Committee on Immunization Practices (ACIP) makes recommendations for vaccine use. The Director of the NVPO coordinates vaccine efforts throughout the PHS and other governmental agencies. The NIH is responsible for conducting and providing funds for a wide variety of biomedical research. The HRSA is responsible for, among many other things, managing the National Vaccine Injury Compensation Program. Other important collaborators in the US government involved in vaccine activities include the US Department of Defense (DOD), and the Department of Veterans Affairs. Consistent with the goal of harmonization, the Enterprise and Industry Directorate-General (DG Enterprise) of the European Commission, the European Medicines Agency (EMA), and the FDA concluded confidentiality arrangements on 12 September 2003 covering medicinal products, including vaccines that are subject to evaluation or authorization under the centralized procedure in Europe. The confidentiality arrangements allow the EMA of the European Commission and the FDA in the United States to exchange information as part of their regulatory processes. The types of information covered by the arrangements include legal and regulatory issues, scientific advice, orphan drug designation, inspection reports, marketing authorization procedures, and postmarketing surveillance. These confidentiality arrangements were reviewed at a meeting between the DG Enterprise, the EMA, and the FDA in Brussels in March 2006. The review resulted in an agreement to intensify the existing cooperation in the area of medicinal products, bringing a focus to vaccines (including preparedness for pandemic influenza), pediatric medicines, medicines for rare diseases ("orphans"), oncology, and pharmacogenomics. The FDA has confidentiality agreements with NRAs in Australia, Austria, Brazil, Belgium, Canada, the Council of Europe, the European Commission (DG SANCO), Denmark (drugs), Italy (drugs), the Netherlands, France, Germany, Israel, Japan, Mexico, New Zealand, the Republic of Ireland, Singapore, South Africa, Sweden, Switzerland, the United Kingdom and WHO (although not an NRA). The FDA has relevant memorandums of understanding (MOUs) without confidentiality arrangements with the People's Republic of China, Russia (drugs), and Vietnam. These arrangements have strengthened interactions between the regulatory authorities and have contributed to improving the promotion and protection of public health globally. Historical perspective Although the need for special care in preparing and testing vaccines and antitoxins was foreseen early in their development, before 1902 the production of vaccines and other biologicals was predominantly unregulated by the federal government. 4 Regulation of biologics, vaccines in particular, in the United States has historically been in response to issues of safety. The US Congress enacted the 1902 Biologics Control Act, which contained the initial concepts used for the regulation of biologics, after a major tragedy occurred in St. Louis, Missouri, in 1901. Twenty children became ill and 14 died after receiving an equine-derived diphtheria antitoxin contaminated with tetanus toxin. It was discovered that the diphtheria antitoxin had been prepared from horse serum contaminated with tetanus bacilli. 5 This event stimulated legislation to regulate the sale of biologicals. On July 1, 1902, the Biologics Control Act was signed into law. It prohibited transportation or sale of biologicals unless the manufacturer possessed an establishment and product license. During consideration of this legislation, the following points were recognized: 6 • There could be no assurance of purity if control was limited to inspections and tests of the final products, both because of the limitations of testing techniques and because such tests would need to include all materials, as the products varied with the different animals used in production. Therefore, an effective control would also need to include control of the manufacturing establishments. • The products in question were generally administered directly into the circulatory system or the digestive tract, and there were few remedial measures available if the drugs were impure. • The control of potency was particularly important because, as was noted in the proceedings that led to the development of the legislation, if the first dose proves worthless, the loss of time to produce the product may cost the patient his or her life. These ideas formed an important start for ensuring vaccine safety. They are used as the basis for ensuring safety and effectiveness throughout the world. The history of vaccine control organizations in developed nations has been one of increasing size and complexity. A chronology of the development of the US Biologicals Control Authority is summarized in Table 73-3 and outlined in Figure 73-1 . Table 73-3 Chronology of the Development of Biologic Control Authority Year Legislation enacted Existing organization 1902 Biologics Control Act (Virus, Serum, Toxin Law) of 1902 Public Health Hygienic Laboratory 1930 Hygienic Laboratory, renamed National Institutes of Health (NIH) 1937 Laboratory of Biologics Control (LBC) formed within NIH 1944 Enactment of US Public Health Service Act (42 USC § 262, 263) 1948 LBC incorporated into the National Microbiological Institute (later renamed the National Institute of Allergy and Infectious Diseases) 1955 Establishment of the Division of Biologics Standards (DBS) by the Surgeon General 1972 DBS transferred to US Food and Drug Administration (FDA) to become Bureau of Biologics (BoB) 1982-1983 BoB renamed Office of Biologics Research and Review (OBRR); joined with Office of Drugs Research and Review (ODRR) to form the Center for Drugs and Biologics (CDB) 1987 OBRR renamed Center for Biologics Evaluation and Research (CBER) 1997 Food and Drug Administration Modernization Act of 1997 2007 Food and Drug Administration Amendments Act (FDAAA) Figure 73-1 History of the Food and Drug Law. ICH, International Conference on Harmonisation; IND, Investigational New Drug. The US Congress enacted another significant law in 1902 that expanded the Public Health and Marine Hospital Service. This led to the creation of the first federal agency in which public health issues could be coordinated. The Hygienic Laboratory, the principal research unit of the service, was located in Washington, DC. Within this organization, the Biological Control Service assumed responsibility for the regulation of three products: smallpox vaccine, tetanus antitoxin, and diphtheria antitoxin. These products were defined as biologicals. In 1930, the Hygienic Laboratory was reorganized, expanded, and renamed the National Institutes of Health. Over time, legislative authorities have evolved to strengthen the regulation of vaccines and other biologics. In 1944 Congress recodified the 1902 Biologics Control Act as part of the US Public Health Service Act (PHS Act) of 1944. The PHS Act incorporated the 1902 Biologics Control Act into Section 351 of the PHS Act (42 U.S.C. 262). 7 As with the 1902 Act, the 1944 PHS Act focused primarily on extensive control over manufacturing methods to ensure purity and safety, and maintained the licensure system for the manufacturing facility and product. Unique to the 1944 PHS Act was Congress's explicit addition of the requirement that biologics manufacturers demonstrate potency as a measure of clinical usefulness. A 1970 amendment added vaccine, blood, blood component or derivative, (or) allergenic products to the statutory list. Under the original act, government inspectors were authorized to inspect manufacturing establishments and to determine whether products were correctly labeled with the name of the product; the name, address, and license number of the manufacturer; and the expiration date of the product, and to determine the manner in which the product was prepared. Section 352 of the Act also permitted the PHS to manufacture biological products should the need arise (eg, if the product could not be obtained from already licensed establishments). 8 This authority has not been used to date. Throughout the life of the PHS Act of 1944, Congress vested the administrative authority for regulation of biologics in several separate agencies. In 1948, the Biologics Control Laboratory joined the NIH Division of Infectious Diseases and Division of Tropical Diseases to form the National Microbiological Institute (later renamed the National Institute of Allergy and Infectious Diseases). Administrative authority for regulation of biologics was originally granted to the National Microbiological Institute. The need for strengthening and expanding control of biologicals became evident in 1955. By this time, many biologicals (blood products as well as vaccines) had been licensed, including inactivated poliovirus vaccine prepared in monkey kidney cell cultures. Unfortunately, when several batches of the vaccine were used for immunization, a number of children developed poliomyelitis. The formaldehyde inactivation and safety test procedures employed were inadequate. It was determined in retrospect that 7 of 17 batches could be shown to contain living poliovirus. A later review indicated that the incompletely inactivated vaccine had caused poliomyelitis in 79 vaccine recipients, 105 family contacts, and 20 community contacts. 9 As a result of this much-publicized "Cutter incident" (Cutter was the manufacturer of the vaccine), administrative authority for the regulation of biologicals was transferred by Congress to the Division of Biologics Standards (DBS), a newly created division within the NIH. Prior to 1972, regulation of biologicals under the NIH had focused primarily on the PHS Act of 1944 and its requirements for safety, purity, and potency. Subsequently, Congress adopted the Consumer Safety Act of 1972, which transferred regulatory authority for the administration of the 1944 PHS Act from the NIH to the FDA. In 1972, the DBS, which was charged with administering and enforcing Section 351 of the PHS Act, was transferred by the Secretary of Health, Education and Welfare to the FDA and became the Bureau of Biologics. Once administrative responsibility for the regulation of biologicals transferred from the NIH to the FDA, the FDA announced its intention to require that all new biologicals satisfy the additional standards of safety and efficacy mandated in the Drug Amendments Act of 1962. This resulted in the transfer of the regulations pertaining to biologics from Part 73 of Chapter I of Title 42 (USC 262) to Chapter I of Title 21 of the Code of Federal Regulations. In 1982, the Bureau of Biologics was renamed the Office of Biologics Research and Review (OBRR) and combined with the Office of Drugs Research and Review to form the Center for Drugs and Biologics. In 1987, the OBRR was separated and renamed the Center for Biologics Evaluation and Research. Federal laws and regulations Although they are not directly related to safety and efficacy, the passage of the Prescription Drug User Fee Act (PDUFA) of 1992 and the FDA Modernization Act (FDAMA) of 1997 have both had an impact on the regulation of vaccines. PDUFA allows the FDA to collect fees from manufacturers to fund the review process. FDAMA, among other things, included measures to modernize the regulation of biologics by synchronizing their review process with that of drugs and eliminating the requirement for an establishment license for biologics. Expedited approval mechanisms for life-threatening conditions were authorized under FDAMA as well. 10 The FDA Amendments Act (FDAAA) of 2007 includes 11 titles that added many new provisions to the FD&C Act. This Act reauthorized and amended several drug and medical device provisions, and it provided the FDA with additional responsibilities and new authorities. 11 PDUFA IV was reauthorized under FDAAA and outlines the 5-year review performance goals for drug and biologics license applications, supplements and resubmissions, meeting management goals, clinical holds, major dispute resolution, special protocol question assessment and agreement, electronic applications and submissions, discipline review, and complete response letters. The provisions of FDAAA that have had a significant impact on the regulations of vaccines and the review process are contained in Title IV, the Pediatric Research Equity Act of 2007 (PREA) and Title IX, Enhanced Authorities Regarding Postmarket Safety of Drugs. Title IX provides the FDA with new funding to collect, develop, and review safety information, and to develop adverse event surveillance systems and analytic tools, and Title IV expands pediatric research with the reauthorization of the Best Pharmaceuticals for Children Act and the Pediatric Research Equity Act. Collectively, these authorities have afforded CBER the authority to accelerate and improve the review process. The FDA's CBER regulates vaccines as biologicals. CBER's current legal authority for the regulation of vaccines derives primarily from Section 351 of the PHS Act and from certain sections of the FD&C Act. The statutes of the PHS Act are implemented through regulations codified in the Code of Federal Regulations (CFR).* The CFR is published annually and contains all changes in regulations that have occurred during the previous year and that have been published in the Federal Register. Regulations are adopted in conformity with the Administrative Procedure Act. 12 Thus, before a regulation can be established, repealed, or revised, it must be proposed and published in the Federal Register with an invitation to all interested individuals or parties to comment within a prescribed time, commonly a period of 1 to several months. Once comments are received, they are evaluated and considered by the FDA before publication of the final regulation in the Federal Register. Title 21 of the CFR, parts 600 through 680, contains regulations specifically applicable to vaccines and other biologicals. In addition, because vaccines meet the legal definition of a drug under the FD&C Act, manufacturers must comply with regulations for current good manufacturing practices (CGMPs) (parts 210 and 211). Regulations applicable to vaccines and other biological products are summarized in Table 73-4 . These regulations cover not only the methods and establishment standards pertaining to the manufacture of a biological product to ensure that the product is safe and meets the quality and purity characteristics that are claimed by the manufacturer, but also requirements for performing clinical trials (eg, 21 CFR 312). Table 73-4 Regulations Applicable to the Development, Manufacture, Licensure, and use of Vaccines Title 21, Code of Federal Regulations, Chapter 1—FDA, DHHS Subject of regulations Subchapter F—Biologics (parts 600-680 *) 600 Biological products, general, definitions Establishment standards Establishment inspection Adverse-experience reporting 601 Licensing 610 General biologicals: product standards Subchapter C—Drugs: General 201 Labeling 202 Prescription drug advertising 210 CGMP in manufacturing, processing, packing, or holding of drugs 211 CGMP for finished pharmaceuticals Subchapter D—Drugs for human use 312 New drugs for investigational use 314 Applications for FDA approval to market a new drug or an antibiotic drug Subchapter A—General 25 Environmental impact considerations 50 Protection of human subjects 56 Institutional review boards 58 Nonclinical laboratory studies, CGMP regulations CGMP, current good manufacturing practice; FDA, US Food and Drug Administration; DHHS, Department of Health and Human Services. * Parts 606, 607, 640, 660 and 680 apply to blood, blood products, diagnostic tests, and allergenics. A single set of basic regulatory requirements applies to all vaccines regardless of the technology used to produce them. The regulatory approval criteria contained in Title 21 CFR also apply to vaccines, regardless of their indication or intended target population. Section 351 of the PHS Act (42 USC 262) states that a biologics license application can be approved if it can be demonstrated that “(a) the biological product that is the subject of the application is safe, pure and potent; and (b) the facility in which the biological product is manufactured, processed, packed or held meets standards designed to assure that the biological product continues to be safe, pure, and potent”. Some of the more pertinent operational definitions for biologics contained in the statutes and 21 CFR are as follows: • Section 351 of the PHS Act defines a biological product as any virus, therapeutic serum, toxin, antitoxin, vaccine, blood, blood component or derivative, allergenic product, or analogous product applicable to the prevention, treatment, or cure of diseases or conditions of humans. Thus vaccines clearly are regulated as biological products. • Safety is defined as the relative freedom from harmful effect to people affected directly or indirectly by a product when prudently administered, taking into consideration the character of the product in relation to the condition of the recipient at the time. Thus, the property of safety is relative and cannot be ensured in an absolute sense. • Purity is defined as the relative freedom from extraneous matter, regardless of whether it is harmful to the recipient or deleterious to the product. Usually, the concepts of purity and safety coincide; purity most often relates to freedom from such materials as pyrogens, adventitious agents, and chemicals used in manufacture of the product. • Potency is defined as the specific ability or capacity of the product, as indicated by appropriate laboratory tests or by adequately controlled clinical data obtained through administration of the product in the manner intended, to effect a given result. Potency, as thus defined, is equivalent to the concept that the product must be able to perform as claimed, and, if possible, this must correspond with some measurable effect in the recipient or correlate with some quantitative laboratory finding. • Standards mean specifications and procedures applicable to an establishment or to the manufacture or release of products that are designed to ensure the continued safety, purity, and potency of biological products. The word standard is also used with a secondary meaning, usually in the sense of a reference preparation, such as a bacterial or viral antigen that can be used in evaluating potency or, in some cases, safety and purity. • The regulations regarding biological products, in addition, define effectiveness as the reasonable expectation that, in a significant proportion of the target population, pharmacologic or other effects of the biological product, when administered under adequate directions for use and warnings against unsafe use, will serve a clinically significant function in the diagnosis, cure, mitigation, treatment, or prevention of disease in humans. • Current good manufacturing practices define a quality system that manufacturers use as they build quality into their products. The regulations outline the minimal manufacturing, quality-control, and quality-assurance requirements for the preparation of a drug or biological product for commercial distribution. For example, approved products developed and produced according to CGMPs are safe, properly identified, of the correct strength, pure, and of high quality. The FDA also periodically publishes various guidelines and guidance documents with regard to the manufacture and clinical evaluation of biologicals. These documents published by the FDA do not have the force of law but are intended to provide useful and timely recommendations; those applicable to vaccines are listed in Table 73-5 . Guidance documents are particularly useful as a means for the Agency to provide recommendations that are current with areas of rapidly progressing science, and for specifying a degree of detail beyond that included in the regulations. Several FDA regulations and guidance documents have had a direct impact on the review of vaccines for licensure by the FDA, such as the Guidance for Industry: How to Comply with the Pediatric Research Equity Act (2005), and the Guidance for Industry: Considerations for Plasmid DNA Vaccines for Infectious Disease Indications (2007). Some of these regulations and guidance documents evolved from an effort to streamline the regulatory process, whereas others were written to facilitate the development of new vaccines with new technologies, such as the Guidance for Industry: Clinical Data Needed to Support the Licensure of Trivalent Inactivated Influenza Vaccines (2007), the Guidance for Industry: Clinical Data Needed to Support the Licensure of Pandemic Influenza Vaccines (2007), the Guidance for Industry: Characterization and Qualification of Cell Substrates and Other Biological Material Used in the Production of Viral Vaccines for the Prevention and Treatment of Infectious Diseases (2010), and the Guidance for Industry: Considerations for Developmental Toxicity Studies for Preventive and Therapeutic Vaccines for Infectious Disease Indications (February 2006). These documents can be obtained through CBER's Web site (www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/default.htm). Table 73-5 Current Guidance Documents as of April 2012* Applicable to Development, Manufacture, Licensure, and Use of Vaccines Document Date Guidance documents Guidance for Industry and FDA Staff: FDA Acceptance of Foreign Clinical Studies Not Conducted Under an IND—Frequently Asked Questions 2012 Guidance for Industry: M3(R2) Nonclinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals Questions and Answers 2012 Draft Guidance for Industry: Determining the Extent of Safety Data Collection Needed in Late Stage Premarket and Postapproval Clinical Investigations, February 2012 Guidance for Industry: Process Validation: General Principles and Practices 2011 Guidance for Industry: Bar Code Label Requirements—Questions and Answers 2011 Guidance for Industry: Clinical Considerations for Therapeutic Cancer Vaccines 2011 Guidance for Industry: General Principles for the Development of Vaccines to Protect against Global Infectious Diseases 2011 Guidance for Industry: Characterization and Qualification of Cell Substrates and Other Biological Materials Used in the Production of Viral Vaccines for Infectious Disease Indications 2010 Guidance for Industry: Content and Format of the Dosage and Administration Section of Labeling for Human Prescription Drug and Biological Products 2010 Draft Guidance for Industry: Format and Content of Proposed Risk Evaluation and Mitigation Strategies (REMS), REMS Assessments, and Proposed REMS Modifications 2009 Guidance for Industry: Considerations for Plasmid DNA Vaccines for Infectious Disease Indications 11/2007 Guidance for Industry: Clinical Data Needed to Support the Licensure of Pandemic Influenza Vaccines 2007 Guidance for Industry: Clinical Data Needed to Support the Licensure of Trivalent Inactivated Influenza Vaccines 2007 Guidance for Industry: Toxicity Grading Scale for Healthy Adult and Adolescent Volunteers Enrolled in Preventive Vaccine Clinical Trials 2007 Draft Guidance: Emergency Use Authorization of Medical Products 2007 Guidance for Industry: Considerations for Plasmid DNA Vaccines for Infectious Disease Indications 2007 Guidance for Industry: Development of Preventive HIV Vaccines for Use in Pediatric Populations 2006 Guidance for Industry: Reports on the Status of Postmarketing Studies: Implementation of Section 130 of the Food and Drug Administration Modernization Act of 1997 2006 Guidance for Industry: Clinical Studies Section of Labeling for Prescription Drugs and Biologics: Content and Format 2006 Draft Guidance for Industry: Labeling for Human Prescription Drug and Biological Products: Implementing the New Content and Format Requirements 2006 Guidance for Industry: Adverse Reactions Section of Labeling for Human Prescription Drug and Biological Products: Content and Format 2006 Draft Guidance for Industry: INDs: Approaches to Complying with CGMP during Phase 1 2006 Guidance for Industry: Considerations for Developmental Toxicity Studies for Preventive and Therapeutic Vaccines for Infectious Disease Indications 2006 Guidance for Industry: Fast Track Drug Development Programs: Designation, Development, and Application Review 2006 Guidance for Industry: Quality Systems Approach to Pharmaceutical Current Good Manufacturing Practice Regulations 2006 Guidance for Industry: Providing Regulatory Submissions to the Center for Biologics Evaluation and Research (CBER) in Electronic Format: Lot Release Protocols 2006 Guidance for Industry: Development and Use of Risk Minimization Action Plans 2005 Draft Guidance for Industry: How to Comply with the Pediatric Research Equity Act 2005 Guidance for Industry: FDA Review of Vaccine Labeling Requirements for Warnings, Use Instructions, and Precautionary Information 2004 Guidance for Industry: Sterile Drug Products Produced by Aseptic Processing Current Good Manufacturing Practice 2004 Draft Guidance for Industry: Vaccinia Virus: Developing Drugs to Mitigate Complications from Smallpox Vaccination 2004 Draft Guidance for Industry: Postmarketing Safety Reporting for Human Drug and Biological Products Including Vaccines 2001 Draft Guidance for Industry on Recommendations for Complying with the Pediatric Rule 2000 Guidance for Industry: Formal Meetings with Sponsors and Applicants for PDUFA Products 2000 Guidance for Industry: Submitting and Reviewing Complete Responses to Clinical Holds 2000 Guidance for Industry: Content and Format of Chemistry, Manufacturing and Controls Information for a Vaccine or Related Product 1999 Guidance for Industry: Providing Clinical Evidence of Effectiveness for Human Drugs and Biological Products 1998 Draft Guidance for Industry: Stability Testing of Drug Substances and Drug Products 1998 Guidance for Industry: Environmental Assessment of Human Drug and Biologics Applications 1998 Guidance for Industry for the Evaluation of Combination Vaccines for Preventable Diseases: Production, Testing and Clinical Studies 1997 Guidance for Industry: Changes to an Approved Application: Biological Products 1997 Guidance on Alternatives to Lot Release for Licensed Biological Products 1994 Guidelines Validation Guidance for Industry: Process Validation: General Principles and Practice (Revision of the 1987 guidance: General Principles of Process Validation) 2011 Determination of Residual Moisture in Dried Biological Products 1990 Validation of the Limulus Amebocyte Lysate Test 1987 Points to consider Supplement: Nucleic Acid Characterization and Genetic Stability 1992 Production and Testing of New Drugs and Biologicals Produced by Recombinant DNA Technology 1985 FDA, US Food and Drug Administration; PDUFA, Prescription Drug User Fee Act. * Guidance documents are available at www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/default.htm. Also available at no charge from the Office of Communication, Training and Manufacturers Assistance, HFM-40, 1401 Rockville Pike, Rockville, MD 20852-1448. Stages of the regulatory review of biological products Premarketing phase The regulatory requirements for biological products cover the entire life cycle of the product from the pre–Investigational New Drug (IND) stage, through the premarketing (consisting of the various IND phases and prelicensure) and postmarketing stages. The pre-IND stage consists of laboratory development, preclinical testing of candidate vaccines, and development of the manufacturing process. The clinical development of a new drug in the United States usually begins with a sponsor approaching the FDA for permission to conduct a clinical study with an investigational product through submission of an IND application form.* These requirements can be found in the IND regulations. 13 Sponsors are encouraged to request a pre-IND meeting with the FDA to discuss preclinical studies, clinical study design, and data requirements that require resolution before the initiation of clinical trials. Prior to initiating phase 1 clinical trials sponsors should discuss, and reach an agreement on the preclinical studies prior to or during the pre-IND meeting with the FDA. Considerations for these studies are evaluated on a product-specific basis and requirements may differ depending on the type of vaccine, its manufacturing process, and mechanism of action. The preclinical toxicity study should be adequate to identify and characterize potential toxic effects of a vaccine in order to conclude that it is reasonably safe to proceed to clinical investigation. If the target population of the vaccine includes pregnant women and women of childbearing potential, developmental toxicity studies may be considered. Adequate information should be provided to FDA on the clinical plan, and protocols should be submitted for CBER review prior to initiation of animal studies. Toxicity study reports should be submitted with the new IND or Master File. Additional toxicity studies may be necessary as product/clinical development continues. In the application, the sponsor (1) describes the composition, source, and method of manufacture of the product and the methods used in testing its safety, purity, and potency; (2) provides a summary of all laboratory and preclinical animal testing; and (3) provides a description of the proposed clinical study and the names and qualifications of each clinical investigator. The FDA has a maximum of 30 days to review the original IND application and determine whether study participants will be exposed to any unacceptable risks. As part of the IND process, each clinical investigator files information describing his or her qualifications for performing clinical trials, details of the proposed study, and assurance that a number of conditions specified by the regulations will be met. A signed informed consent must be obtained from each study participant. Approval for the study must be obtained in advance from a local institutional review board. The regulations also cover the evaluation of the preclinical laboratory animal studies undertaken to support the use of the product in humans. Investigational phase Only licensed vaccines may be shipped from one state to another; however, during the premarketing phase, interstate shipment of products for investigational use is allowed under the law and regulations. There are generally three separate phases in the clinical evaluation of experimental biologicals at the premarketing stage (Figure 73-2 ). These phases may overlap, and the clinical testing may be highly iterative because multiple phase 1 or 2 trials may be performed as new data are obtained. Phase 1 trials are intended primarily to provide a preliminary evaluation of safety and immunogenicity. These trials are typically conducted in a small number (eg, 20 to 80) of closely monitored adult volunteers. If the ultimate target population for the vaccine is infants or young children, as is commonly the case, the product is then usually evaluated in a stepwise progression from older to younger age groups, down into the first year of life. It is not always simple to distinguish between phase 1 and phase 2 studies; however, in general, phase 2 studies are larger, perhaps involving up to several hundred participants. Phase 2 studies are often randomized and well controlled, and they provide further information on safety and immunogenicity. Dosage-ranging studies are included in phase 2 clinical development. In some cases, phase 2 studies provide preliminary data on the vaccine's activity against the infectious disease of interest. Intermediate clinical studies may be done after phase 2 that are not considered efficacy studies. These studies are referred to as so-called phase 2b studies (there is no regulatory definition for phase 2b), and are designed to assist in determining whether to move a candidate vaccine into a larger phase 3 trial. Phase 2b studies are generally smaller than the pivotal phase 3 trial, and are not designed to have the statistical power required for a phase 3 study. If the data from the phase 2b study are encouraging, a phase 3 efficacy study is still required to support licensure of the candidate vaccine. Phase 2b studies may increase the clinical development time for a vaccine; however, phase 2b studies may be useful for evaluating and screening different vaccine candidates. Phase 2b studies have been used to evaluate candidate HIV vaccines, and were done prior to the large phase 3 efficacy trials for the human papillomavirus vaccines. Phase 3 studies are large-scale trials involving more extensive testing to provide a more thorough assessment of safety as well as a definite assessment of efficacy; moreover, these studies often include the pivotal efficacy trials as well as expanded safety studies. Figure 73-2 Sequence of key events in product development through the premarketing experimental Investigational New Drug (IND) and licensing phases and the postapproval marketing phase. Dashed lines indicate additional research/development submissions when significant changes are made in the product or its indications. BLA, biologics license application. The general considerations for clinical studies to support licensure of a vaccine include demonstrations of safety and efficacy (immunogenicity may be sufficient in some cases) and evaluation of simultaneous administration with other licensed vaccines. Ideally, efficacy is demonstrated in randomized, double-blind, well-controlled trials. The endpoints will be product specific, and they may be clinical disease endpoints or immune response endpoints if efficacy against clinical disease has been previously established and there are immune correlates or surrogates of that protection. In recent years, because of interconnected variables such as study design and the incidence of the disease to be prevented, efficacy trials for various vaccines have involved a broad range in the number of study participants, from thousands to tens of thousands. For example, clinical disease endpoint studies that are designed to demonstrate that a new vaccine is not inferior to an already existing product of the same type generally require larger numbers than those in which a new vaccine can be compared with a control that has no activity against the clinical disease. The incidence of the disease to be prevented in the study population is also important. As an example, convincing evidence for the effectiveness of the plasma-derived hepatitis B vaccine in a population at high risk required only 549 vaccinees and 524 placebo recipients. In contrast, a trial to show that pneumococcal 7-valent polysaccharide conjugate vaccine was successful in preventing a low incidence of invasive disease caused by the Streptococcus pneumoniae capsular serotypes included in the vaccine enrolled close to 40,000 children who were randomized equally to receive the pneumococcal conjugate vaccine or an unrelated control vaccine. Immunogenicity studies may be requested to provide data on the immune response of target populations for the vaccine if they are different from those populations in which the efficacy studies were done. These studies are known as bridging studies. In other words, immunogenicity data may be used to bridge to existing clinical endpoint efficacy data. The 1998 FDA Guidance for Industry: Providing Clinical Evidence of Effectiveness recommends two efficacy trials as the standard; however, one trial may be adequate if the results are compelling, which is often the case for vaccine clinical endpoint efficacy trials (eg, robust-data, multicenter trials with a high level of efficacy). 14 Safety is one of the most important considerations when evaluating new vaccines and modifications to currently licensed vaccines. The initial responsibility for determining vaccine safety starts with clinical investigators and vaccine manufacturers. The FDA is responsible for ensuring that clinical trials are done under good clinical practices, a requirement essential for the evaluation of safety data intended to support a license application. In general, when evaluating safety, one must compare the risk of the vaccine-preventable disease with the risk of the adverse events potentially associated with the vaccine, and these may change over time. As an example, the reported association between Rotashield (rotavirus vaccine, live, oral, tetravalent, manufactured by Wyeth) and intussusception resulted in the additional requirement for the evaluation of the safety of RotaTeq (live, oral pentavalent human-bovine reassortant rotavirus vaccine, manufactured by Merck) with respect to intussusception. This clinical trial enrolled over 70,000 infants divided equally between RotaTeq and placebo. The primary safety hypothesis was that the oral RotaTeq would not increase the risk of intussusception relative to placebo within 42 days of any dose. The intended target population should also be taken into consideration in assessing the adequacy of the safety database. For routinely administered childhood vaccines in the United States, the target population would be the birth cohort in the United States (approximately 4 million/year). This is generally a healthy population, and a government body (eg, states or local governments) may mandate vaccination. Common reactions can be studied adequately in hundreds of individuals, but many thousands will be required to define low-incidence adverse reactions. For vaccines evaluated in clinical endpoint efficacy trials, a large safety database is likely to derive from a double-blind, randomized, well-controlled efficacy study. However, for vaccines evaluated in immunogenicity endpoint studies, additional studies are likely to be needed to obtain an adequate safety database. Additional controlled safety studies are often requested when the numbers of subjects included in the efficacy studies are deemed insufficient to provide adequate safety data. The studies need to be designed in such a way that statistical methods can be applied to their evaluation. Safety studies may be unblinded if the number of injections, route of administration, or schedule differs between groups, in particular when infants and young children are involved. Phase 2 safety studies should provide data on common local and systemic reactions to the study vaccine. Phase 2 clinical development should also include immunogenicity and preliminary safety data on the concurrent administration of the study vaccine with other vaccines, if relevant. Phase 3 safety studies are designed to evaluate less common reactions, may be unequally randomized, and may have a simplified trial design for assessing less common adverse events in large trials. If a vaccine is recommended on the same schedule as other routinely recommended vaccines, safety and immunogenicity data should be obtained in prelicensure studies to support simultaneous administration. Licensing phase When IND studies are nearing completion, or have been completed, and the sponsor believes that there are adequate data to demonstrate that the product is safe and effective for its intended use, the sponsor may apply for a license to manufacture and distribute the product. Precise production methods and procedures should be defined at this stage, and the manufacturing process standardized. Before the submission of a biologicals license application (BLA), a pre-BLA meeting with the FDA is strongly encouraged to discuss the sponsor's product development plan. The FDA has determined that delays associated with the initial review of a BLA can be reduced or avoided by exchanges between the sponsor and the agency concerning the proposed marketing application. The primary purpose of this exchange is to uncover any major unresolved problems, to identify those studies that the sponsor is relying on as adequate and sufficiently well controlled to establish the product's effectiveness, to identify the status of ongoing studies, to acquaint FDA reviewers with the general information to be submitted in the BLA (including technical information), to review methods used in the statistical analysis of the data, and to discuss the best approach for the presentation and formatting of data in the application. Arrangements for such a meeting are to be initiated by the sponsor with the division responsible for review of the IND. Historically, two license applications were required for submission, one for the product and one for the establishment in which the product is to be manufactured. However, as a result of the enactment of the FDAMA of 1997, only a BLA is required. The BLA should contain detailed information about the product (clinical and manufacturing) as well as information concerning the manufacturing facility and equipment. To obtain a biologics license for a new vaccine under section 351 of the PHS Act, an applicant submits a BLA to the Director of CBER's Office of Vaccines Research and Review (OVRR). This application contains data derived from nonclinical laboratory and clinical studies that demonstrate that the manufactured product meets prescribed requirements for safety, purity, and potency. The BLA should contain information that supports compliance with standards addressing requirements for (1) organization and personnel, (2) buildings and facilities, (3) equipment, (4) control of components, containers, and closures, (5) production and process controls, (6) packaging and labeling controls, (7) holding and distribution, (8) laboratory controls, and (9) records to be maintained. Furthermore, a full description of manufacturing methods; data establishing stability of the product through the dating period; samples representative of the product for introduction or delivery for introduction into interstate commerce; summaries of test results performed on the lots represented by the submitted samples; specimens of the labels, enclosures, and containers; and the address of each location involved in the manufacture of the biological product should be included in the BLA. For the FDA to provide sponsors with the most useful advice for preparing a BLA as well as the adequacy of information to support a BLA, the sponsor should submit the following information to OVRR's application division within 2 to 4 weeks in advance of the meeting, depending on the type of meeting: (1) an executive summary of the clinical studies to be submitted in the application, (2) a proposed format for organizing the submission, including methods for presenting the data, (3) information on the status of needed or ongoing studies, and (4) any other information for discussion at the meeting. An application for a biologics license is not considered as filed (or accepted by the agency for review) until CBER determines that it has received all pertinent information and data from the applicant. In this regard, CBER can refuse to file a BLA if it deems the submission to be incomplete. Additionally, the manufacturing facility must be inspection-ready at the time the BLA is submitted. The applicant is also required to include either an environmental assessment or a claim for categorical exclusion from the requirement to submit an environmental assessment or an environmental impact statement. An internal CBER multidisciplinary committee performs the scientific review of the BLA, and members of this review committee are selected on the basis of the expertise required to review the application. This process occurs for each BLA or supplement to a BLA in which significant changes are proposed. During the review, there are discussions and exchanges of correspondence between the sponsor and the CBER review committee concerning issues that may arise. During the FDA review of the BLA, an announced Prior Approval Inspection (PAI) of the manufacturing facility is performed. This inspection is designed as an in-depth review of the facilities, records, total production process, methods, equipment, quality control procedures, and personnel. With the implementation of the BLA process, changes have occurred in the scope of issues reviewed during the PAI. Instead of the manufacturer submitting detailed records with the BLA regarding studies on cleaning validation, monitoring data for pharmaceutical-grade water, facility support systems (eg, clean steam, compressed air, and building management systems) and other facility-related systems, a more detailed review of this type of data is done on site during the PAI. PAIs tend to require longer periods of time for the FDA inspectors to be in the facility because of the increased scope of issues that are reviewed on site. If licensure is denied after inspection for the original license application, reinspection will occur after assurance has been received that all deficiencies that were the basis of the denial have been corrected. After CBER reviews the entire package of information in the BLA, its advisory committee (the Vaccines and Related Biological Products Advisory Committee [VRBPAC]) and consultants, if needed, are asked to review and comment on the adequacy of the data to support safety and efficacy in the target population. The standards for safety and efficacy are relative; that is, the benefit-to-risk ratio of a biological product is considered. The regulations and standards allow a range of safety and efficacy, as is scientifically appropriate. The VRBPAC's advice is seriously considered in CBER's decision regarding licensure, and in developing recommendations for use to be given in the package insert. The committee may recommend additional studies to be performed either before or after approval. Other components of the BLA review include product labeling, which describes the indications for use, contraindications, dosage and possible adverse effects; protocols for the manufacturing and testing of the number of product lots specified to establish the consistency of the process; and confirmatory testing results within CBER of samples of in-process material or product in final containers and conformance to existing regulations. Once CBER determines that the data and information from the applicant are satisfactory and support the safety and efficacy of the product, the product is licensed. Mechanisms for advancing new vaccines through the review process have been developed for severe and life-threatening illnesses. These mechanisms include fast-track development, as well as accelerated approval and priority review of marketing applications. The Fast Track programs of the FDA are designed to facilitate the development, and expedite the review, of new drugs and biologicals that are intended to treat serious or life-threatening conditions and that demonstrate the potential to address unmet medical needs. Accelerated approval, 21 CFR 601.40, may be granted for certain biological products that have been studied for their safety and effectiveness in treating serious or life-threatening illnesses and that provide meaningful therapeutic benefit over existing treatments. Such an approval is based on there being adequate and well-controlled clinical trials that establish that the product has an effect on a surrogate endpoint that is reasonably likely, based on epidemiologic, therapeutic, pathophysiologic, or other evidence, to predict clinical benefit. Approval under this pathway is subject to the requirement that the sponsor study the biological product further, to verify and describe its clinical benefit, where there is uncertainty as to the relationship of the surrogate endpoint to clinical benefit. Recently, the option to pursue an accelerated approval pathway for trivalent inactivated influenza vaccines became available to sponsors if a shortage of influenza vaccine exists for the US market at the time the new vaccine is approved. In this case, the FDA interprets the accelerated approval regulation as allowing accelerated approval of an influenza vaccine during a shortage because influenza is a serious and sometimes life-threatening illness. The FDA has used this regulatory mechanism to approve four trivalent inactivated influenza vaccines, GlaxoSmithKline's (GSK's) Fluarix, ID Biomedical Corporation's FluLaval, Novartis's Agriflu, and CSL's Afluria. Accelerated approval was more recently used to license a new Haemophilus influenza vaccine, Hiberix, manufactured by GSK. The accelerated approval regulations give the FDA flexibility with respect to the types of endpoints that can be relied on to support marketing approval, but they do not affect the quantity or quality of evidence needed to demonstrate substantial evidence of effectiveness or safety. Any endpoint considered appropriate to be relied on to support approval, whether a surrogate endpoint or a clinical endpoint, must be supported by substantial evidence of effectiveness. Products regulated by CBER are eligible for priority review if they provide a significant improvement in the safety or effectiveness of the treatment, diagnosis, or prevention of a serious or life-threatening disease. The FDA has 6 months to complete the review of a new BLA it designates as a priority, as opposed to 10 months for the completion of the review of a standard BLA submission. In 2002, the FDA amended the biological products regulations to incorporate 21 CFR 601.90, Approval of Biological Products When Human Efficacy Studies Are Not Ethical or Feasible. This rule, referred to as the animal rule, allows the use of animal efficacy data in lieu of human efficacy data when human challenge studies cannot be conducted ethically and field efficacy studies are not feasible because of infectious disease epidemiology (in the case of vaccines). In these situations, certain drug and biological products (eg, vaccines) that are intended to reduce or prevent serious or life-threatening conditions caused by lethal or permanently disabling toxic chemical, biological, radiologic, or nuclear substances may be approved for marketing based on evidence of effectiveness derived from appropriate studies in animals and additional supporting data. Safety, pharmacokinetics, and immunogenicity data are still necessary in humans. Under the animal rule, the FDA licensure of a product for which safety has been established and the requirements of 21 CFR 601.60 have been met is based on adequate and well-controlled animal trials, when results of these animal studies establish that the product is reasonably likely to provide clinical benefit to humans. The FDA can rely on the evidence from animal studies to provide substantial evidence of the efficacy of these products when the following criteria are met: • There is a reasonably well understood pathophysiologic mechanism for toxicity of the chemical, biological, radiologic, or nuclear substance and its amelioration or prevention by the product. • The effect is demonstrated in more than one animal species that is expected to react with a response that is predictive for humans, unless the effect is demonstrated in a single animal species that represents a sufficiently well characterized animal model (in other words, the model has been adequately evaluated for its responsiveness) in predicting the response in humans. • The animal endpoint is clearly related to the desired benefit in humans, which is generally the enhancement of survival or prevention of major morbidity. • The data or information on the pharmacokinetics and pharmacodynamics of the product or other relevant data or information in animals and humans is sufficiently well understood to allow selection of an effective dose in humans, and it is reasonable to expect the efficacy of the product in animals to be a reliable indicator of its efficacy in humans. The animal rule does not apply if the product can be approved on the basis of standards described elsewhere in FDA regulations (eg, accelerated approval based on surrogate markers or clinical endpoints other than on survival or irreversible morbidity). Approval of products under the animal rule will require early and multiple discussions with the FDA. Applicants will need detailed justifications as to why efficacy trials are not feasible or ethical for their products of interest. Before beginning the pivotal trials, pilot studies in animals are expected, and a prospective primary endpoint should be selected. Additionally, with regard to the pivotal trials, prospective statistical plans should be in place. The FDA's advisory committees also may be consulted before acceptance of the animal efficacy trial proposal or after the agency's review of the BLA. Emergency use authorization (EUA) is another regulatory mechanism by which the FDA can accelerate the availability of vaccines and other pharmaceutical products. Under an EUA, the FDA can authorize the use of an unapproved product or the unapproved use of an approved product when an emergency or a potential emergency exists. Section 564(b)(1) of the FD&C Act was amended by the Project BioShield Act of 2004 to allow the Secretary of Health and Human Services to authorize the introduction into interstate commerce of a drug, device, or biological product intended for use in an actual or potential emergency. Before an EUA can be issued by FDA, the Secretary must declare an emergency justifying the authorization based on one of the following: • A determination by the Secretary of Homeland Security that there is a domestic emergency or a significant potential for an emergency that involves a heightened risk of attack with a specified biologic, chemical, radiologic, or nuclear agent or agents • A determination by the Secretary of Defense that there is a military emergency or a significant potential for an emergency that involves a heightened risk of attack with a specified biologic, chemical, radiologic, or nuclear agent or agents • A determination by the Secretary of Health and Human Services that a public health emergency under section 319 of the PHS Act affects, or has a significant potential to affect, national security, and that it involves a specified biological, chemical, radiologic, or nuclear agent or agents or a specified disease or condition that may be attributable to such agent or agents Once the Secretary of Health and Human Services declares an emergency, the FDA may authorize the emergency use of a particular product if the other statutory criteria and conditions are met. Based on the particular circumstances, the process for authorization can be expected to range in duration from hours to days. The Secretary has delegated the authority to issue an EUA under section 564 of the FD&C Act to the FDA Commissioner. The Pediatric Research Equity Act of 2003 (Public Law 108-155) amended the FD&C Act by adding Section 505(B) addressing product development for pediatric subjects from birth through 16 years of age. 15 PREA requires all applications that are submitted under Section 505 of the FD&C Act or Section 351 of the PHS Act (42 U.S.C. 262) for a new active ingredient, new indication, new dosage form, new dosing regimen, or new route of administration to contain a pediatric assessment unless the applicant has obtained a waiver or deferral from the FDA. Under PREA, the pediatric assessment must contain data adequate to assess the safety and effectiveness of the drug or the biological product for the claimed indications in all relevant pediatric subpopulations and data to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. FDAAA 2007 reauthorized and made several changes to PREA, primarily to enhance FDA oversight and applicant accountability for the agreed-on pediatric assessments. A new provision was written under FDAAA 2007 that directs the FDA to establish an internal review committee with pediatric expertise, the Pediatric Review Committee (PeRC). This committee is required to provide consultation to FDA review divisions on all pediatric plans and assessments and on all deferral and waiver requests. FDAAA 2007 also specified certain labeling changes that must be made pursuant to an applicant's pediatric assessment. FDAAA 2007 also specifies adverse event reporting requirements for products with labeling changes that are a result of a pediatric assessment. Specifically, during the 12 months from the date that such a labeling change is made, all adverse event reports are reviewed by the FDA Pediatric Advisory Committee (PAC). After review, the PAC will make recommendations regarding whether the FDA should take action in response to such reports and whether the current pharmacovigilence plan is adequate. Postmarketing phase Modifications to the manufacturing process may occur after licensure, such as scale-up or change in equipment to optimize the production process. Furthermore, clinical studies with the product may also be performed after licensure as the manufacturer seeks additional indications for product use (eg, new target populations that would benefit from vaccination). For most new approvals, manufacturers may be asked to commit to completing specific postmarketing or so-called phase 4 studies—for example, to provide additional assessments of less common or rare adverse events or to further assess the duration of vaccine-induced immunity. These studies also may be designed to collect additional safety data in large numbers of vaccine recipients, as well as to focus on issues that were identified during the prelicensure testing. Submission of status reports for certain postmarketing studies are required by regulation. In particular, this requirement for status reports pertains to postmarketing studies for clinical safety, efficacy, and pharmacokinetics, and for nonclinical toxicology to which an applicant committed in writing before licensure. 16 If the manufacturer wishes to significantly modify the manufacturing process or directions for vaccine use, prior approval must be obtained from the FDA before these changes can be implemented. The applicant is required to submit an account of these changes to the appropriate license applications. For the past several years, efforts have been made to simplify and categorize manufacturing reporting requirements so as to facilitate the implementation of important improvements in the production processes, testing methods, equipment, or facilities or to make changes in personnel. Proposed changes in manufacturing methods that have a substantial potential to have an adverse effect on the safety or effectiveness of the product may not become effective until notification is given of CBER's approval. A change in 21 CFR 601.12 has been implemented that classifies changes into (1) those sufficiently significant with regard to safety, purity, potency, and effectiveness of the product to require preapproval of a supplemental application before product distribution, (2) those of lesser importance, for which the manufacturer must provide notification 30 days before distribution of product made using the change, and (3) changes for which the manufacturer need only notify the agency by submission of an annual report. The guidance document, Changes to an Approved Application: Biological Products (1997), is available on CBER's Web site (www.fda.gov/downloads/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Guidances/Blood/UCM170166.pdf); it provides more details on the changes to this regulation. After issuance of the license, there is continued surveillance of the product and of the manufacturer's production activities. For most licensed vaccines, samples are submitted along with protocols for each lot prepared by the firm that provide the details of production and a summary of test results. Although not required by law or regulation, CBER often performs selected laboratory tests. The type and extent of confirmatory testing performed by CBER depend on several factors, such as the newness of the product or the difficulties that may have arisen with manufacture or use of the product. Release or rejection is based on a review of all test results, including those done by the manufacturer and those performed by CBER. Alternatives to official lot release are allowable under the provisions outlined for extensively characterized products having a track record of continued safety, purity, and potency. 17 New regulations have been developed that clearly specify the factors that are to be evaluated and include measures that allow additional products to be considered in this category. To be considered, the manufacturer must be able to produce a vaccine that repeatedly meets the standards for potency, purity, and stability of bulk and final container material while using a consistent process. Important factors to be considered are the nature of the product with respect to correlation between the measure of potency and biological activity, and effectiveness. Surveillance samples and protocols may be required to be submitted to CBER at predetermined intervals. Licensed establishments are inspected at least every 2 years, with the exception of those facilities manufacturing influenza vaccines, which are inspected annually. The purpose of the inspection is to determine whether licensed products are manufactured and tested as described in the license application and in accordance with applicable regulations. Manufacturers who fail to meet product standards or who are not in compliance with CGMPs may have their licenses suspended or revoked, depending on the nature of the potential health hazards created. The major issues observed during inspections can be categorized in three major areas: (1) process-related issues, (2) quality unit–related issues, and (3) facility- and production environment–related issues. Some examples of process validation issues include lack of documentation of time limits for major steps in the production process, lack of validation of rework or reprocessing steps in the manufacturing process, and lack of data to support in-process specifications. Quality unit–related issues include the appropriate reporting of out-of-specification results and process deviations (including adequate investigations into causes), appropriate documentation of product release, and adequate training of personnel. Facility and production monitoring concerns include controlling production environments by appropriately monitoring heating, ventilation, and air conditioning system performance and microbial quality (eg, pressure differentials, appropriate sampling sites, frequency of sampling). Other concerns in the facility include adequate cleaning, sanitization, storage, and changeover procedures for multiproduct areas and equipment. If the inspection team finds CGMP deficiencies in an already licensed facility, the team may remain in the facility until they have achieved an audit that provides confidence in the ability of the firm to reproducibly manufacture a safe and potent product. Section 901 of Title IX of the FDAAA 2007 revised the FD&C Act by adding Section 505(o) authorizing the FDA to require certain postmarketing studies and clinical trials for prescription drug and biological products approved under Section 505 of the FD&C Act or Section 351 of the PHS Act (42 U.S.C. 262). Section 901 of FDAAA 2007 also created new Sections 505-1 and 505(o)(4) of the FD&C Act, authorizing the FDA, under certain circumstances, to require risk evaluation and mitigation strategies and safety-related labeling changes, respectively. Before FDAAA 2007, the FDA used the term postmarketing commitment (PMC) to refer to studies to which manufacturers committed as a condition of approval of the product. For vaccines, these studies were usually intended to further evaluate the safety and immunogenicity of a product. These PMCs were agreed on by FDA and the applicant before licensure. Before FDAAA 2007, FDA required postmarketing studies in the following situations: (1) for accelerated approvals for products approved under 505(b) of the FD&C Act or under Section 351 of the PHS Act that require postmarketing studies to demonstrate clinical benefit, (2) for deferred pediatric studies, when studies are required under PREA, and (3) for animal efficacy rule approvals, when studies to demonstrate safety and efficacy in humans are required at the time of use. Under new Section 505(o) of the FD&C Act, the FDA is authorized to also require postmarketing studies or clinical trials at the time of approval or after approval if the FDA becomes aware of new safety information. Section 505(o)(3)(B) states that postmarketing studies and clinical trials may be required to (1) assess a known serious risk related to the use of the drug involved, (2) assess signals of serious risk related to the use of the drug, and (3) identify an unexpected serious risk when available data indicate the potential for a serious risk and when the adverse event reporting system is not adequate. The FDA has defined a clinical trial as any prospective investigation in which the sponsor or investigator determines the method of assigning treatment or other intervention to one or more human subjects. A study is all other investigations, such as investigations using humans that are not clinical trials as just defined (eg, observational epidemiologic studies), animal studies, and laboratory experiments. The FDA has issued guidance for industry that describes the type of studies and clinical trials that are required (postmarketing requirement [PMR]) under the FDAAA 2007, and those that will remain agreed-on commitments (PMC). A PMR describes all required postmarketing studies or clinical trials including those required under accelerated approval, PREA, the animal rule, and FDAAA. Examples of required studies are pharmacoepidemiologic studies designed to assess a serious risk, trials with a primary safety endpoint, preclinical studies investigating specific end-organ toxicities, and pharmacokinetic studies in the indicated population at potential risk for high drug exposure that could result in toxicity. Studies that generally would not be considered required postmarketing studies or clinical trials are agreed-on studies (PMC) and include biologic quality studies (such as manufacturing, stability, and immunogenicity studies that do not have a primary safety endpoint), trials in which the primary endpoint is related to further defining efficacy, and pharmacoepidemiologic studies designed to examine the natural history of disease or background rates for adverse events. Since passage of FDAAA 2007, several new vaccines have been approved with either PMRs or PMCs. FDA has the authority to monitor the progress of postmarketing studies or trials by requiring the applicant to submit an annual status report. Applicants are required to provide a timetable for study completion, a periodic status report on the status of the study including whether enrollment has begun, the number of participants enrolled, the expected completion date, and whether any difficulties in completing the study have been encountered. Managed review process The regulatory review in CBER incorporates a managed and integrated regulatory process that is continuous from discovery to postmarketing, called the Managed Review Process. 18 It relies on a strong project management infrastructure. The Regulatory Project Manager (RPM) is an essential member of each review team. The RPM coordinates the review of regulatory submissions in accordance with CBER policy, procedures, and regulations, and serves among other functions as a facilitator to drive the review process forward. Project management is used to facilitate and coordinate the review of these submissions and the resolution of issues. Biological product development consists of four phases: pre-submission, investigational, marketing, and postmarketing. CBER's Managed Review Process is a system designed to effectively and efficiently review all regulatory submissions and is targeted to these phases of development. The Managed Review Process begins when a sponsor requests a pre-IND meeting that may result in the submission of an IND and eventually a BLA. The internal review process in CBER begins with an initial review of a submission for scientific content and compliance with the regulations. Members of a multidisciplinary review team are selected on the basis of their expertise with the type of product and its method of manufacture. It is the responsibility of CBER's review component to evaluate submissions and to recommend appropriate regulatory action to facilitate the approval of safe and effective biological products. The review includes an evaluation of chemistry, manufacturing, and controls information; the manufacturing facility and equipment; preclinical and clinical data on the safety, efficacy, pharmacology, and toxicology; the suitability of clinical trial design; and analysis of clinical data derived from such trials. In addition, reviewers monitor for conformance with FDA regulations in all phases of biological product development, including postmarketing. CBER scientists also perform research in the areas of statistical and epidemiologic analysis, clinical trial design, and chemistry, manufacturing, and control specific to product issues, and they contribute to policy development. Surveillance activities are performed to ensure that the safety of biological products is not compromised. These activities ensure the rapid availability and approval of safe and effective biological products. Sponsors are encouraged to avail themselves of meetings with CBER reviewers to discuss and review general clinical developmental plans for their product. Meetings between sponsors and the agency are frequently useful in resolving questions and concerns raised during the course of a clinical investigation. The FDA encourages such meetings to the extent that they aid in the evaluation of the vaccine and in resolving scientific issues concerning the product. The general principle underlying the conduct of such meetings is that there should be free, full, and open communication about any scientific or medical question that may arise. Agreements reached at PDUFA meetings (eg, pre-IND, IND, pre-BLA, and BLA meetings) are recorded in official minutes taken by FDA personnel and provided to the sponsor. The minutes, along with any other written material provided to the sponsor, will serve as a permanent record of any agreements reached. Barring a significant scientific development that requires otherwise, studies conducted in accordance with the agreement shall be presumed to be sufficient in objective and design for the purpose of obtaining marketing approval for the drug. Detailed information on the conduct of regulatory meetings is described in 21 CFR 312.47. Pre-IND meetings are particularly important for new sponsors, especially with products that incorporate novel features. Other meetings also are encouraged at critical points throughout the IND review, including end-of-phase-2 meetings. The purpose of an end-of-phase-2 meeting is to assess the adequacy of the phase 2 safety and immunogenicity data that support advancement to phase 3, to evaluate the phase 3 plan and draft protocols, and to identify any additional information necessary to support a marketing application for the uses under investigation. Although the end-of-phase-2 meeting is designed primarily for INDs involving new molecular entities, such as new vaccines (including combinations of two or more existing vaccines), or major new or expanded indications for a currently marketed vaccine, a sponsor of any IND may request and obtain an end-of-phase-2 meeting. The end-of-phase-2 meeting should be held before major commitments of effort and resources to specific phase 3 studies are made. Vaccine testing Vaccines are tested during the prelicensure as well as the postlicensure phase. Testing procedures are developed from a combination of the understanding of past adverse experiences and the best current knowledge regarding the potential for new ones. From past experience, a few highly important issues must continue to receive special attention. For inactivated vaccines, a clear understanding of the kinetics of inactivation is key; this was the lesson of the Cutter incident mentioned previously. For live vaccines, the agent must be at a stable level of attenuation; it must not become overattenuated or revert to virulence. The Brazilian experience, in which yellow fever vaccine appeared to revert to neurovirulence after multiple passages, demonstrated the need for a seed lot system in which the number of passages from the parent virus to the passage level used as vaccine is restricted. 19 All vaccines require an extensive search for extraneous contaminants. The experience in which human serum was used as a stabilizer for yellow fever vaccine and caused hundreds of cases of long-incubation hepatitis virus infection underscored this need. 20 The FDA requires that cell substrates and vaccine viral seeds used in production be appropriately selected and tested to ensure that they do not introduce any unintended risks. The current cell substrates used to manufacture licensed vaccines are primary avian or monkey cells, diploid cells, one continuous cell line, Vero, as well as yeast and insect cells. Refer to Table 73-6 for a list of cell substrates in current US licensed vaccines. In 2010, the FDA published the final guidance, Characterization and Qualification of Cell Substrates and Other Biological Starting Materials Used in the Production of Viral Vaccines for the Prevention and Treatment of Infectious Diseases. This guidance document provides important advice for manufacturers on using cell cultures to produce vaccines against infectious diseases and to use modern technologies to ensure that they meet the highest safety expectations. Selection of a cell substrate influences the safety and purity of the biological product manufactured in it. Cell substrates are evaluated on a case-by-case basis, but characterization of any cell substrate used for the development and manufacture of a vaccine should address certain general issues that might affect the safety and purity of vaccine products manufactured in them. Examples of such issues include karyotype and tumorigenic phenotype of the cell substrate, the identity and genetic stability of the cell substrate and virus seeds, and the requirement that the vaccine be free of extraneous infectious microorganisms and potential oncogenic agents. Historically, only primary cells were used widely for viral vaccine production, and, although primary cells are still used in the manufacture of some viral vaccines, major concerns have arisen over the passage of adventitious agents from primary cells into the product and thus, potentially, into vaccine recipients. In the early 1960s, exogenous and endogenous contamination of primary monkey kidney cells (PMKCs) with simian virus 40, and chicken embryo fibroblasts (CEFs) with avian leukosis virus were reported. PMKCs and CEFs are still used in the production of viral vaccines, but these cells are required to be well characterized and extensively tested prior to use. Issues related to cell substrates have been discussed in a variety of forums. 21, 22 Oncogenicity is defined as the process by which agents immortalize cells and endow them with the capacity to form tumors. The demonstration that viruses can be oncogenic in mammalian hosts has produced an intense focus on cell-culture substrate safety as well. If a vaccine is manufactured in a cell substrate that is derived from a tumor, or that has developed a tumorigenic phenotype through an unknown mechanism, it could carry a higher theoretical risk of containing oncogenic substances. It is important to characterize the cell substrate to ensure that it does not contain potentially oncogenic components that could contaminate the final product. Table 73-6 Cell Substrates Used in Current US-Licensed Vaccines Type Substrate Vaccine Live Inactivated Animal tissues Mouse brain — Japanese encephalitis virus Chicken eggs Influenza, yellow fever virus Influenza Continuous cell lines (nontumorigenic) African green monkey cells (Vero) Smallpox, rotavirus Poliovirus, Japanese encephalitis virus Diploid cells Human MRC-5 cells Varicella, varicella-zoster Hepatitis A, rabies, poliovirus Human WI-38 cells Rubella, adenovirus types 4 and 7 — Primary cell cultures Chick embryo fibroblasts (CEFs) Measles, mumps Rabies Insect cells Trichoplusia ni — Human papillomavirus Yeast Saccharomyces cerevisiae — Hepatitis B, human papillomavirus The epidemic of bovine spongiform encephalopathy (BSE, also referred to as mad cow disease) and its possible relationship to human variant Creutzfeldt-Jakob disease (vCJD or new variant CJD) has been of special concern. On this account, attention has been centered on the safety of substances derived from mammalian sources, such as media components used for nurturing cell cultures and gelatins used as stabilizers. 23 Bovine-derived materials have traditionally been used in the manufacture of many biological products, including vaccines. Since BSE was first recognized in the United Kingdom in the 1980s, the FDA has been concerned about eliminating any potential for contamination of biological products with the BSE agent. This concern was heightened by the appearance of vCJD in the United Kingdom in 1996. To minimize the possibility of contamination in such products, the FDA, in 1993 and again in 1996, requested that manufacturers not use materials derived from cattle that were born, raised, or slaughtered in countries where BSE is known to exist. The FDA referred manufacturers to the listing of such countries maintained by the US Department of Agriculture (www.aphis.usda.gov/import_export/animals/animal_import/animal_imports_bse.shtml). 24 More information on vaccines and the sourcing of bovine-derived raw materials can be found on CBER's Web site (www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/ucm111476.htm). At the inception of the recombinant DNA era, the possible risk of induction of transformation of cells of the recipient was a major concern. This issue has been approached by careful study of the constructs used and the stability of these constructs and by attempts to reduce extraneous DNA content to levels that are regarded as extremely unlikely to produce an adverse genetic event.25, 26, 27 Residual DNA for continuous nontumorigenic cells, such as low-passage Vero cells, should be limited to less than 10 ng/dose for parenteral inoculation and less than 100 μg/dose for oral vaccines. Cells with tumorigenic phenotypes or other characteristics that give rise to special concerns may require more stringent limitation of residual DNA quantities to ensure product safety. 28 Preapproval test development may be conducted entirely by the sponsor or with involvement of the regulatory agency as well. CBER is particularly likely to become involved if the product is new or represents a novel problem in testing. This involvement, bolstered by laboratory-based capability, has been one of the strengths of the vaccine regulatory program in the United States. As the product moves forward in the regulatory process, the sponsor develops the testing program in greater detail. The final testing methods must be established before major clinical trials for efficacy begin and before the manufacture of batches of product that will be used to demonstrate consistency of manufacture. Among the very first efforts in product development are explorations for a potency assay. A potency test is applied to each product to demonstrate that the product confers protective immunity. The type of test varies depending on the product and is commonly based on studies of immunogenicity or protection from virulent challenge in laboratory animals. However, other in vitro tests can be involved, including virus titration (eg, live vaccines such as polio, measles, mumps, and rubella), antigen content (eg, influenza and inactivated poliovirus vaccines), and biochemical and biophysical measurements (eg, meningococcal conjugate vaccines). Specialized immunological assays are required in the clinical development of vaccines to ascertain the immunogenicity of the vaccine. Ideally, the immune responses measured by these assays should correlate with protection against disease. This is true for many of the currently licensed vaccines; however, for some licensed vaccines, and new vaccines in development it is not always clear which immune response correlates with protection. Standardization of immunogenicity assays across studies, laboratories, and across similar products present challenges, but are necessary to evaluate the effectiveness of vaccines. Correlates are sought between the assay results and the preclinical and, later, the clinical testing results. During the prelicensing phase, research testing results are evaluated to determine which tests under development need to be applied to every batch of product and which do not require such repetition. For example, with hepatitis B vaccines made using recombinant DNA technology, initial evidence for identity, purity, and genetic stability of the protein product was provided by physicochemical, immunologic, and molecular biological test methods. Once the consistency levels of the results of all tests are validated for multiple lots produced during the IND application and product-licensing phases, a determination is made to routinely perform some of these tests, which will be evaluated to ensure the consistent quality of the final product in each lot. The regulation of biologicals includes requirements for testing of licensed products. Certain of these requirements are generally applicable to all products, whereas others are tailored to the specific vaccine. The tests, generally applicable to all products, include those for bacterial and fungal sterility, general safety, purity, identity, suitability of constituent materials, and potency. Sterility testing is performed on both bulk and final container material, using media and conditions of incubation described in the regulations. In addition, cell culture–derived vaccines must be tested for mycoplasmas. The general safety test usually is performed by intraperitoneal inoculation of final container material into mice and guinea pigs to detect the possible presence of gross extraneous contaminants that may have been introduced during the manufacture or filling process. Tests for purity are designed to determine that the product is free of extraneous material, except that which is unavoidable in the manufacturing process described in the approved license application, and they may include tests for residual moisture and pyrogenic substances. Final container material must be identified by a test specific for each product (eg, neutralization of each of the components of live measles, mumps, and rubella vaccine with specific antisera). With regard to constituent materials, the manufacturer must ensure that all ingredients used in the product, such as diluents, preservatives, or adjuvants, meet generally accepted standards of purity. An adjuvant may not be used unless there is adequate proof that it does not adversely affect the safety or potency of the product. The only adjuvants used in currently licensed vaccines in the United States are the aluminum salts and AS04 used in GSK's human papillomavirus (HPV) vaccine Cervarix, although others such as MF59 have been studied experimentally. For cell culture–derived vaccines, extraneous proteins (eg, serum or a serum derivative) should not be present in the final product, or, if serum is used during production to stimulate growth of cultured cells, the calculated concentration in the final medium must not exceed 1 part per million. Antibiotics, except penicillin (and by analogy the β-lactam class), may be employed during the course of viral vaccine production in cell culture. Those antibiotics most commonly added in low concentrations are neomycin, streptomycin, and polymyxin. If antibiotics are present, the package circular must contain a statement concerning possible allergic reactions. With regard to the required testing for licensed biological products, the FDA is reevaluating the appropriateness of selected requirements and the test methods cited in the CFR. For example, the general safety test is required by the FDA for all vaccines. Under 21 CFR 610.11, manufacturers of biological products must perform a test for general safety on biological products intended for administration to humans. This test is used to detect extraneous toxic contaminants that may be present in the product in the final container from every final filling of each lot of the biological product. Technological advances have increased the ability of manufacturers to control and analyze the manufacture of many biotechnology-derived biological products. After more than a decade of experience with these products, the FDA determined that many aspects of a biological product's safety, purity, or potency could be evaluated with tests other than those prescribed in part 610. Another example of the FDA's reexamination of testing requirements in the regulations is in regard to the testing for pyrogenic substances by intravenous injection into rabbits. Because of the variability of in vivo tests such as the rabbit pyrogenicity test, consideration is given to alternative methods such as the limulus amebocyte lysate (LAL) assay for endotoxins. After discussions with the FDA, the LAL assay may be substituted for the rabbit pyrogenicity test and may provide a more quantitative assessment of endotoxin content in a product. The ability to assess endotoxin levels in vaccine lots may also provide a measure of manufacturing and process control from lot to lot. Other, more specific tests designed to provide additional assurance of safety or purity may be required (eg, neurovirulence testing, and cell culture and animal tests for extraneous viruses). Once the product is licensed, the manufacturer's testing must be conducted according to the exact specifications in the manufacturer's license application, and the results of these tests must be within the prescribed limits specified. Tests performed for lot release of hepatitis B vaccines produced using recombinant DNA technology are listed in Table 73-7 . Tests performed for lot release of a typical cell culture–produced live viral vaccine are presented in Table 73-8 . Table 73-7 Testing Requirements for the Release of Recombinant Hepatitis B Vaccines Merck & Co, Inc. GlaxoSmithKline Type of test Test system Stage of production Test system Stage of production Plasmid retention Percentage of host cells with expression construct Fermentation product Percentage of host cells with expression construct Fermentation product Purity and identity Formaldehyde Bulk-adsorbed product SDS-PAGE Nonadsorbed bulk Triton-X100 Bulk-adsorbed product DNA hybridization Nonadsorbed bulk Protein (Lowry) Bulk-adsorbed product Gel electrophoresis Sterile filtered product Antigenic activity (RIA) Nonadsorbed bulk HPSEC Sterile filtered product Protein (SDS-PAGE) Nonadsorbed bulk and final container Thioglycollate medium Final bulk Sterility Thioglycollate medium Final bulk Thioglycollate medium Final container Sterility Thioglycollate medium Final container Guinea pigs and mice Final container General safety Guinea pigs and mice Final container LAL Final container Pyrogen LAL Final container LAL Final container Purity Aluminum Final container Total protein nitrogen Final container Thimerosal Aluminum Final container Thimerosal Final container Potency In vitro relative potency Final container Mouse potency Final container HPSEC, high-performance size-exclusion chromatography; IRA, radioimmunoassay; LAL, limulus amebocyte lysate; SDS-PAGE, sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Table 73-8 Testing Requirements* for the Release of Varicella Virus Vaccine, Live (Varivax) Type of test Test system Stage of preparation Identity of production cells Karyology Production control cells Sterility Thioglycollate/soybean-casein digest Working cell bankControl harvest fluidsVirus harvest fluidsPreclarified bulkClarified bulkFinal formulated bulk Mycoplasma tests Broth or agar; aerobic and anaerobic cell culture systems Working cell bank Control harvest fluids Preclarified bulk Tissue culture safety Simian kidney and MRC-5 cell cultures Working cell bankControl harvest fluidsPreclarified bulk Animal safety Adult and suckling mouse Working cell bankPreclarified bulk Chick embryo (yolk sac and allantoic) Working cell bank General safety Guinea pig and rabbit Working cell bank Guinea pig and mouse Filled container Test for hemadsorbing viruses Guinea pig red blood cells Production control cells Mycobacteria, in vitro Broth and medium slants Preclarified bulk Bovine albumin Immunoassay Clarified bulk Color, appearance, form Visual examination Filled container Moisture Coulometric method Filled container Tissue culture identity Antibody neutralization Filled container Infectivity titration Tissue culture plaque assay Clarified bulk filled container * This is a subset of test performed for this product. Adverse event monitoring An adverse reaction to a biological product is defined as an event associated with the use of a biological product, regardless of whether it is considered product related, and it includes any side effect, injury, toxicity, or sensitivity reaction or significant failure of pharmacologic action. Adverse reaction reports come from several sources. Manufacturers of biologicals, the staff of the US Pharmacopoeia, and other health care professionals are the most common sources, but consumers are also encouraged to report. Manufacturers also report data concerning adverse reactions from postmarketing studies, foreign sources, and both published and unpublished scientific literature. The results of reported adverse reactions associated with vaccine use are compiled and entered into the Vaccine Adverse Event Reporting System. VAERS is a program created as an outcome of the National Childhood Vaccine Injury Act of 1986 (NCVIA) and is administered jointly by the FDA and the CDC. The purpose of VAERS is to detect possible signals of adverse events associated with vaccines. VAERS collects and analyzes information from reports of adverse events (possible side effects) that occur after the administration of US-licensed vaccines. VAERS accepts reports of any adverse event that may be associated with US-licensed vaccines from health care providers, manufacturers, and the public. The VAERS system is not limited to routinely recommended pediatric vaccines; voluntary reports of suspected adverse events occurring after administration of any vaccine are also accepted. The FDA continually monitors VAERS reports for any unexpected patterns or changes in reporting rates of adverse events. The NCVIA also mandated the development of vaccine information sheets for distribution by health care providers to each adult or to the legal representative of each child receiving any vaccine recommended for routine pediatric use by the ACIP. 29 This effort was made to ensure that sufficient written information about the risks from the diseases and the risks and benefits of vaccines would be provided. 30 The materials include information on the diseases, vaccine reactions, possible ways to reduce the risk of major adverse reactions, contraindications, information on groups at high risk for acquiring the diseases that would greatly benefit from vaccination, the existence of the National Vaccine Injury Compensation Program, and federal recommendations about immunization schedules. CBER collaborates with the CDC in the development of this information. Product labeling and advertising Labeling changes are usually initiated by the manufacturer but may be initiated by CBER. Historically, manufacturers have had to obtain prior approval from CBER before the labeling changes were made. The changes to 21 CFR 601.12, mentioned previously, also apply to labeling changes and allow exceptions for a change that adds or strengthens a contraindication, warning, precaution, or adverse reaction; adds or strengthens instructions about dosage and administration intended to increase safe use; or deletes false, misleading, or unsupported indications for use or effectiveness claims. Under this regulation, a manufacturer could effect such changes and, at the same time, submit them and the supporting data to CBER without preapproval. As noted earlier, the FDA regulates the format and content of labels for product containers, cartons, and the package insert that accompanies the product. In January 2006, the FDA issued a final drug-labeling rule, commonly referred to as the physicians' labeling rule (PLR), amending the content and format of prescribing information for human drug and biological products. The new format is intended to provide health care professionals with clear and concise prescribing information by reorganizing critical information into a streamlined format. Moreover, these revisions make it simpler for health care professionals to access, read, and use prescribing information, and enhance the safe and effective use of prescription drug products. New sections were added to the label, such as the highlights section, which contains key benefit and risk information, and a table of contents for the full prescribing information. The initial labeling for a new vaccine is reviewed through the product licensing process described earlier. During this review, the agency considers the draft labeling and clinical studies submitted by the manufacturer, and the ultimate indication for the licensed product is driven by the FDA's review of supportive clinical data submitted by the sponsor. Subsequently, significant changes in labeling, including new indications for use, new dosage forms or regimens, expanded patient populations who receive the product, and additional information regarding safety and effectiveness, require manufacturers to submit a supplemental filing for review and approval by CBER. These materials are reviewed to ensure that they are not false nor misleading—that is, that they comport with the scientific data that the manufacturer developed in the application and data acquired subsequent to product approval. Unlike other product labeling, the promotional labeling and advertising are not subject to clearance ahead of time; however, they are similarly monitored for misleading claims. These documents must also meet the standard of fair balance—that is, claims of efficacy are balanced with information about the product's safety. Special considerations Combination vaccines Since the early part of the 20th century, vaccine combinations and the simultaneous separate administrations of different vaccines have been important as effective means of enhancing the efficiency of immunization programs. Combination vaccines are composed of two or more antigens that are intended to induce protection against multiple infectious diseases or several different serotypes of the same organism. The antigens contained in combination vaccines are either formulated together by the manufacturer or physically mixed by a health care provider just before administration. Both approaches require licensure by the FDA. In the United States, combinations of diphtheria and tetanus toxoids, and these toxoids combined with pertussis vaccine (DTP), were licensed by the late 1940s. Since that time, the number of combinations has grown steadily, now including the individual types of live and inactivated poliovirus vaccines; several combinations of measles, mumps, and rubella vaccines; combinations of Haemophilus influenzae type b conjugate vaccine with diphtheria and tetanus toxoids and acellular pertussis (DTaP) or hepatitis B vaccines; trivalent influenza vaccines; quadrivalent influenza vaccine; pneumococcal vaccines with multiple serotypes; the combination of hepatitis A and hepatitis B vaccines; and the combination of DTaP, inactivated poliovirus, and hepatitis B vaccines. The current success in developing new vaccine products administered in the first years of life has complicated vaccine schedules and has put special pressure on the desire for additional combinations. Products for which this approach might be an option in the future include combinations of killed antigens already in use (eg, DTaP, Haemophilus type b conjugate, 13-valent pneumococcal conjugate, hepatitis A and B, and the poliovirus vaccines). Live viral vaccines routinely recommended early in life are measles-mumps-rubella and varicella, and licensure of a combination of these live virus vaccines is now available as ProQuad manufactured by Merck. The manufacturing process and preclinical and clinical studies performed before licensure of a new combination vaccine are all intensively scrutinized during product development. Vaccines are complex mixtures that contain not only viral or bacterial antigens but also other components such as preservatives, adjuvants, stabilizers (eg, gelatin and sorbitol), and buffers and salts. Of particular concern is the compatibility of these components in the final combination. A combination vaccine may fail because of manufacturing issues such as the physicochemical interactions in the product, or biological interference among the combined attenuated immunizing agents, or immunologic interference, detected either in animal studies or during human clinical trials. 31 Preclinical immunogenicity studies may be very useful in determining the characteristics of antibody-induced responses (subclass, affinity, functionality, epitope recognition). Animal models may be helpful in comparing the responses to the combined product and the individual vaccines. Similarly, an appropriate challenge model can serve to bolster the human data collected later in development. There are several published examples of clinical interference where the administration of combination vaccines resulted in the diminution of the immune response to one or more of the antigens in the combination when compared with the separate administrations of the individual components of the vaccines. 32 One such example was the observation of depressed responses to the pertussis antigen in one experimental Haemophilus type b conjugate–DTaP combination vaccine that was not demonstrable with other similar combinations. 33 An important consideration is that a preservative that accompanies one component of a combined product must not have a deleterious effect on another component. 34 Additionally, the impact of the preservative on the potency and stability of all active components in the combination must be evaluated. Similarly, when one or more of the components incorporates an adjuvant, the combination could affect antigen binding. Some of the bound antigen could be lost, or a previously unbound antigen could become adsorbed. Commonly, combinations raise issues related to successful potency, purity, identity, and sterility testing and may require alternative assay strategies. When potency tests of individual components are already approved for use on licensed products, it may be necessary to demonstrate that these tests still produce valid information when applied to a new combination vaccine. 35 For example, vaccine components may have to be tested at an earlier bulk stage of manufacture rather than in the final container. Adjuvants or residual antibiotics also may require that adjustments be made in sterility test procedures. Although reactions to combination vaccines have not been a major issue, safety needs to be carefully evaluated for each new product. In addition to approved combination vaccines, separate products are commonly administered simultaneously. Reactivity after simultaneously administered vaccines may be additive, but generally it has not been shown to be enhanced. 36, 37 Clinical trials are required whether the components of a new combination product were previously licensed or not. These studies are ordinarily randomized and controlled by comparisons between the combination and the individual component vaccines. Clinical observations for reactions in several thousand subjects, coupled with laboratory studies of immunogenicity, are usually sufficient to assess the safety and effectiveness of the combination. The development of new combination vaccines continues to present unique challenges to vaccine manufacturers as well as regulatory authorities. A coordinated effort and dialogue between the two parties is important to help bring these new products to the market, especially as the complexity of manufacturing and clinical evaluation increases. Vaccines to counter emerging infectious diseases and biothreat agents Immunization programs in the United States have been remarkably effective at reducing morbidity and mortality from the most common naturally transmitted infectious diseases (eg, polio, measles, diphtheria). However, emerging infectious diseases (EIDs), from pandemic influenza to severe acute respiratory syndrome, and biological threats that have the potential to be intentionally released into the general population also pose a threat to global public health. Vaccines will continue to be an important medical countermeasure (MCM) against a broad range of infectious diseases from anthrax to smallpox to influenza to something new or unexpected. Moreover, major devastating infectious diseases, such as tuberculosis and malaria, and even common bacteria such as staphylococci, are increasingly resistant to available treatments, so the development of safe and effective vaccines against these infectious diseases is essential. The development of MCMs such as vaccines to prevent the spread of infectious diseases, whether newly emerged or intentionally released, presents numerous challenges, but it is essential to protect public health. The regulatory framework is in place to evaluate vaccines regardless of the technology used to develop them; however, current approaches to the development and evaluation of needed vaccines are not always sufficient to quickly and fully meet global and domestic needs. The development of essential MCMs must take full advantage of scientific innovations in basic science and product development. The US military has implemented vaccination programs to protect troops against several biological threats; however, the risk-to-benefit ratio for protecting civilians against agents of bioterrorism is more difficult to assess. Presently, there is one licensed smallpox vaccine in the United States, ACAM2000 from Sanofi Pasteur Biologics. New smallpox vaccines also are being developed under IND applications, with the goal to seek licensure, and new vaccinia immune globulin preparations to treat certain complications of smallpox vaccination are approved. There is one licensed anthrax vaccine in the United States, Anthrax Vaccine Adsorbed (BioThrax), from Emergent BioDefense Operations. There are currently no licensed vaccines available in the United States for plague, tularemia, or viral hemorrhagic fever viruses (eg, Ebola, Marburg, Lassa, and New World arenaviruses); however, new vaccines against some of these agents are being developed under IND applications. There are significant scientific and regulatory challenges associated with developing and testing new vaccines against EIDs and biothreat agents. Vaccines against EIDs are more likely to use novel technologies, and the science behind these technologies may be more complex (involving, eg, the use of novel cell substrates, the need to develop alternative potency assays, and the need to identify surrogate markers in humans or animals that predict vaccine effectiveness). With regard to bioterrorism, the goal of the FDA is to facilitate the development of vaccines and other biological products, drugs, and diagnostic products to respond to bioterrorist threats. In this effort, the FDA works with interagency groups within the DHHS, such as the Biomedical Advanced Research and Development Authority, the CDC, and the NIH, as well as the DOD and Department of Homeland Security to prepare for responding to an emergency. As part of the interagency group, the FDA also participates in setting a broad-based US research agenda to facilitate the government's preparedness against bioterrorism and EIDs. Key activities of CBER include enhancing its regulatory science, and research and review activities in this area to expedite the development and licensure of new biological products, including vaccines and new uses of existing products. For licensure, a counter-bioterrorism product, as for any product, must have an acceptable quality, safety, efficacy, and potency profile. Likewise, production and quality control must also be in compliance with CGMPs. A committed, continuous investment in regulatory science is essential to producing MCMs against public health threats. As noted in a review of MCMs, “Enhancement and ultimate application of updated regulatory science and scientific review capacity will help strengthen the MCM regulatory process and thus streamline the MCM development process. FDA will undertake a new initiative … designed to focus on augmenting the tools used to assess the safety, efficacy, and quality of medical products, with a particular focus on MCMs, and to get them from concept through the approval process efficiently”. 38 An example of how the FDA's regulatory science efforts have assisted the agency in facilitating the licensure of vaccines against emerging diseases and biothreats is the successful public-private partnership during the 2009 H1N1 influenza pandemic, which resulted in the development and approval of safe and effective vaccines against the pandemic in record time. It is not always possible to test whether a vaccine or treatment will work against a new or emerging infectious disease, or against a biothreat, because the threat may be rare or even nonexistent at the time the vaccine or therapy needs to be developed. Moreover, many vaccines against EIDs and biothreats pose difficult challenges with regard to obtaining clinical efficacy data. For many of these infectious agents or toxins, human efficacy trials are not feasible because natural exposure no longer occurs (eg, smallpox), it occurs at a very low incidence, or it occurs in an unpredictable manner. Furthermore, human challenge studies that would involve exposing healthy human volunteers to a lethal or permanently disabling agent in the absence of a proven therapy to counter the agent cannot be performed. Nonetheless, the requirements for licensure of vaccines against biothreat agents are the same as for any biological—that is, safety, efficacy, and manufacturing consistency must be demonstrated. The animal rule described earlier is one regulatory mechanism that allows the FDA to address the challenges of obtaining clinical efficacy data for these products if the results of adequate and well-controlled animal studies establish that the product is reasonably likely to provide clinical benefits to humans. Animal testing is often the only available option, but many diseases lack even good animal models, and animal studies are technically difficult to conduct and typically limited in size. Therefore, regulatory science is needed to develop and validate improved predictive models. Regulatory science can also support the identification and validation of surrogate measures of product efficacy. Biomarkers that predict efficacy are not yet available for most terrorism threats, emerging pathogens, or major global infectious diseases. Efforts to develop, refine, and validate new biomarkers may lower development costs and improve and speed the development of safe and effective products for unmet public health needs. In summary, vaccines against EIDs and biothreat agents present unique issues for clinical development and evaluation by the FDA. Overall planning and coordination with the FDA will be necessary to move these products toward licensure and into distribution, if they are needed in the case of a bioterrorist threat. More flexible and agile approaches to product development and manufacturing will be needed to speed the development of vaccines against EIDs and biothreat agents. FDA guidance and engagement with partners will be critical to make sure these products can move from the future into the present. Emerging post-licensure issues: detection of porcine circoviruses in rotavirus vaccines Inadvertent contamination of vaccines with extraneous infectious agents is a major safety challenge and inherent risk in the manufacturing process. Microbial contamination can occur at any point during the development of a biological product. Manufacturers are required to have controls in place to ensure the identity, potency, quality, and purity of vaccines. By regulation, licensed vaccines are required to be free of extraneous material except when it is unavoidable in the manufacturing process described in the approved biologics license application. 39 In addition, current FDA recommendations for the detection and evaluation of cell substrates used to produce viral vaccines are described in the FDA Final Guidance for Industry entitled, “Characterization and Qualification of Cell Substrates and Other Biological Materials Used in the Production of Viral Vaccines for Infectious Disease Indications”. 40 Adventitious agent testing utilizes a combination of methods and strategies and is performed at multiple stages during the manufacturing process to maximize the chance of detecting contaminants. Use of multiple strategies for testing provides assurance, to the extent possible, that products are “free” from adventitious agents. The regulatory requirement for cGMP also ensures that products are manufactured at the highest standards. 41 Technologies for detection and discovery of new adventitious agents continue to evolve at a very rapid pace. Some new technologies have the potential to detect adventitious agents not previously known or detected in cell substrates and biological products; however, these technologies also introduce scientific and regulatory challenges that must be addressed on a case-by-case basis. Occasionally, the FDA encounters unexpected findings after licensure that may have a potential impact on the quality and safety of a product. One such example occurred in the early 1960s with the discovery of simian virus 40 (SV40) in rhesus monkey kidney cells, and stocks used to produce poliovirus for production of inactivated polio vaccine (IPV). 42 The final step in IPV production involved formalin inactivation of poliovirus. SV40 is relatively resistant to formalin inactivation and thus low levels of live SV40 remained present in lots of IPV. 43 The federal government required that new lots of IPV be manufactured free of SV40. The discovery of endogenous avian retroviruses was another example of an unexpected finding that brought concern to the FDA, specifically on the quality and safety of vaccines produced in eggs or cells derived from chick embryos. This case arose in the mid 1990’s when a highly sensitive PCR test called product enhanced reverse transcriptase (PERT) assay was developed. The reverse transcriptase (RT) enzyme is present in all retroviruses, so the presence of RT enzyme suggested that retroviruses could be present. In 1996, this test was used to demonstrate that previously undetectable quantities of reverse transcriptase were present in some vaccines produced in avian cells. 44 Studies by the FDA and the vaccine industry demonstrated that this endogenous avian retrovirus was a defective particle that does not induce productive infections in cell culture. FDA concluded that based on these results, along with the long safety record of vaccines produced in hen's eggs, the benefits of the vaccines outweighed any potential risk of the presence of endogenous avian retroviruses in the vaccines. The most recent unexpected finding in a licensed vaccine occurred in 2010 and involved the discovery of porcine circoviruses in rotavirus vaccines. A team of investigators used a novel metagenomic method consisting of viral particle purification, massively parallel pyrosequencing, and viral sequence similarity searches to search for adventitious viruses in eight live attenuated vaccines: oral polio virus vaccine, rubella virus vaccine, measles virus vaccine, yellow fever virus vaccine, varicella virus vaccine, two rotavirus vaccines, and measles/mumps/rubella vaccine. 45 DNA sequences originating from porcine circovirus-1 (PCV-1) were detected in two batches of GSK's live attenuated rotavirus vaccine, Rotarix®. PCV-1 is a small, circular virus composed of a single strand of DNA. PCV-1 is found commonly among pigs, but is not known to cause disease in pigs nor other animals, including humans. The investigators did not identify these sequences in the RotaTeq® rotavirus vaccine manufactured by Merck. Upon notification of the findings, GSK initiated studies and confirmed that DNA from PCV-1 was present in the Rotarix® vaccine, as well as in the cell bank and seed from which the vaccine is derived. FDA began its own laboratory studies and also confirmed the presence of DNA from PCV-1 in Rotarix® vaccine. These findings indicated that the DNA from PCV-1 was likely present since the early stages of the vaccine's development, including during clinical studies. Merck's live attenuated rotavirus vaccine, RotaTeq®, was tested by Merck and CBER for potential PCV contamination, and fragments of PCV-1 and PCV-2 DNA were also detected in RotaTeq®. There was no evidence at the time that DNA from PCV-1 in Rotarix® posed a safety risk. Pre- and post-market studies demonstrated that Rotarix® is highly effective at preventing serious gastrointestinal disease caused by rotavirus. In addition, no serious or unexpected safety concerns had been identified in postmarket surveillance of Rotarix®. While additional information was gathered, as a precautionary measure, the FDA recommended on March 22, 2010, that clinicians and public health professionals in the United States temporarily suspend the use of Rotarix®. CBER sought external input on the findings of PCV-1 in Rotarix from a special meeting of the Vaccines and Related Biological Products Advisory Committee (VRBPAC), which convened on May 7, 2010. GSK and FDA researchers updated the committee on their most recent findings and the status of current investigations. The investigations at both GSK and FDA included studies designed to determine whether the PCV-1 DNA is particle associated, whether infectious PCV-1 virus is present in the vaccine, and whether PCV-1 is capable of replication in Vero cells or other mammalian cells, including human cell lines. At the time of the convening of the VRBPAC, the findings of PCV-1 and PCV-2 in RotaTeq® were too preliminary for discussion so the VRBPAC was asked to discuss the significance of the most recent findings of PCV-1 in Rotarix® vaccine, the implications of the data for continued use of Rotarix®, and the need for any additional experiments or data. Based on all of the available information and feedback from the VRBPAC, CBER concluded that the safety of rotavirus vaccines (Rotarix® and RotaTeq®) is supported by available data and the benefits of the vaccines, which are known, are substantial and outweigh any theoretical risk. Therefore CBER recommended the continued use of both rotavirus vaccines. The FDA considered the following in reaching this conclusion: (1) Is there a known risk or is it a theoretical risk? (2) What are the clinical implications (any safety concerns regarding the agent)? (3) What is the safety record of the product from clinical trials, controlled post-marketing observational studies, and post-marketing passive surveillance (e.g., VAERS reports)? (4) What is the benefit/risk profile for the product (benefit/risk determination must be made for each region or country)? CBER's laboratory investigation later determined that PCV-1 DNA in Rotarix® is particle associated and represents near full length DNA and particles are replication competent in cell culture. No evidence was found that PCV-1 replicated in the human host, i.e., no seroconversion. CBER's results for RotaTeq® confirmed that PCV-1 and PCV-2 DNA fragments are present in Rotateq®. The following regulatory actions were taken by CBER: the FDA approved revised product labels to include information about the presence of PCV-1 in Rotarix® and the presence of PCV-1 and PCV-2 DNA in RotaTeq®. The FDA continues to assess its current regulatory recommendations for testing of other vaccines for the presence of unknown adventitious agents. To assist with this assessment, the FDA sent written inquiries to manufacturers of licensed viral vaccines and/or combination vaccines containing viral antigens asking them to provide additional information. Specifically, FDA requested information regarding plans that the manufacturers may have to implement additional adventitious agent testing methods as part of their manufacturing process as these methods become available, including, but not limited to, screening for PCV and PCV DNA, as well as any additional in-process testing for adventitious agents that they may have recently added, but not reported to FDA. CBER's comprehensive approach to address unexpected findings in licensed products involves a thorough scientific investigation, analysis of findings, and a safety risk assessment. Before serious regulatory decisions are made by the FDA, i.e. suspension of use, all available scientific data are evaluated, and laboratory studies are initiated, if feasible. It is critical for the regulatory authority to communicate with manufacturers and provide guidance where appropriate on investigational plans. CBER's VRBPAC is available and can be supplemented if necessary with additional experts to provide scientific expertise and guidance. The investigation process must be transparent to the public and public health entities should be notified and kept informed of the investigation. It is also critical to communicate with the international community to share information and harmonize efforts among various National Regulatory Authorities. The detection of PCV-1 sequences in Rotarix® vaccine raises complex questions with potential regulatory implications, not only in regard to PCV-1 specific testing of vaccines, but in regard to the general use of advanced analytical methods for characterizing vaccine cell substrates. The power of the new methodology used to detect the PCV-1 sequences suggests that such technologies may uncover the presence of adventitious agents that might not be detected with current methods. Implementing routine use of such methods has benefits as well as challenges and risks. Detection methods for adventitious agents continue to evolve and improve. New methods may have higher sensitivity and throughput. Novel viruses (not previously known) are frequently being discovered and could be present in existing or new cell substrates and biological products. These new technologies could allow detection of previously unknown or undetectable agents, and may further support safe product development. Conclusion The primary responsibility of NRAs is to ensure the quality, safety, and effectiveness of pharmaceutical products. The implementation of a strong regulatory system will facilitate these goals, which are especially critical for vaccines that are inherently more difficult to develop, characterize, and manufacture than most pharmaceutical products. The FDA has developed a managed review process that provides regulatory oversight through all phases of vaccine development. Advances across a wide range of scientific disciplines have enhanced the prospects of developing new and better vaccines. Novel vaccine approaches, such as recombinant vaccines, and novel adjuvants and delivery systems pose regulatory challenges for NRAs. However, NRAs should be dynamic and flexible entities, as they strive to develop regulatory requirements to address the evolving science. Furthermore, NRAs must be prepared to address public health emergencies that will require expedited approval mechanisms, such as biological terrorist events, pandemic influenza, and other emerging infectious diseases. Acknowledgments I would like to acknowledge the employees in the Office of Vaccines Research and Review and the Office of Compliance and Biologics Quality/CBER for their assistance in the preparation of this manuscript. Access the complete reference list online at http://www.expertconsult.com