Hepatitis A (HepA) vaccination is recommended routinely for children at age 12–23
months, for persons who are at increased risk for hepatitis A virus (HAV) infection,
and for any person wishing to obtain immunity. Persons at increased risk for HAV infection
include international travelers to areas with high or intermediate hepatitis A endemicity,
men who have sex with men, users of injection and noninjection drugs, persons with
chronic liver disease, person with clotting factor disorders, persons who work with
HAV-infected primates or with HAV in a research laboratory setting, and persons who
anticipate close contact with an international adoptee from a country of high or intermediate
). Persons experiencing homelessness are also at higher risk for HAV infection and
severe infection-associated outcomes. On October 24, 2018, the Advisory Committee
on Immunization Practices (ACIP)* recommended that all persons aged 1 year and older
experiencing homelessness be routinely immunized against HAV. The ACIP Hepatitis Vaccines
Work Group conducted a systematic review of the evidence for administering vaccine
to persons experiencing homelessness, which included a set of criteria assessing the
benefits and adverse events associated with vaccination. HepA vaccines are highly
immunogenic, and >95% of immunocompetent adults develop protective antibody within
4 weeks of receipt of 1 dose of the vaccine (
). HAV infections are acquired primarily by the fecal-oral route by either person-to-person
transmission or via ingestion of contaminated food or water. Among persons experiencing
homelessness, effective implementation of alternative strategies to prevent exposure
to HAV, such as strict hand hygiene, is difficult because of living conditions among
persons in this population. Integrating routine HepA vaccination into health care
services for persons experiencing homelessness can reduce the size of the at-risk
population over time and thereby reduce the risk for large-scale outbreaks.
In 2017 in the United States, 1.42 million persons used an emergency shelter or transitional
housing program at some point during the year (
). Estimates of homelessness are higher when unsheltered persons are considered. Some
studies estimate that 2.3 million to 3.5 million persons experience homelessness each
), and persons of color are disproportionately affected (
). In 2017, on a single night, an estimated 553,742 persons experienced homelessness
in the United States, approximately 35% of whom were in unsheltered locations (
). Although the number of persons experiencing homelessness has declined overall since
2007, the number of unsheltered persons experiencing homelessness in major cities
has increased, and disparities remain (
). Persons experiencing homelessness are at 1.5 to 11.5 times the risk for mortality
compared with the general population (
). Homelessness has been associated with substantial health inequalities, including
shorter life expectancy; poor access to health care, resulting in delayed clinical
presentation; higher morbidity; and greater use of acute hospital services, often
for preventable conditions (
HAV infection is associated with poor sanitation and hygiene and is transmitted by
the ingestion of contaminated food or water or by direct contact with an infectious
person. Congregate living conditions, both within and outside shelters, increase the
risk for disease transmission, which can result in outbreaks (
). Recent outbreaks with direct HAV transmission among persons reporting homelessness
signal a shift in HAV infection epidemiology in the United States (
). During 2017, a total of 1,521 outbreak-associated HAV cases were reported from
California, Kentucky, Michigan, and Utah, with 1,073 (71%) hospitalizations and 41
(3%) deaths; the majority of infections were among persons reporting homelessness
or injection or noninjection drug use (
). The person-to-person HAV outbreaks involving persons who use drugs or persons experiencing
homelessness are ongoing, and case counts and geographic dispersion increased substantially
As of October 12, 2018, approximately 7,000 outbreak-associated cases had been reported
from 12 states (
Hepatitis A vaccines are critical to the prevention of HAV infection among persons
experiencing homelessness. Detectable antibodies persist for at least 20 years after
HepA vaccination in childhood (
), and antibodies persist for an estimated 40 years or longer based on mathematical
modeling and anti-HAV kinetic studies (
). Although recommended as a 2-dose series, evidence of protection for up to 11 years
exists for 1 dose of single-antigen vaccine (
); clinical and outbreak response experience suggests that lifelong protection is
possible after 1 dose. Owing to limited access to health care and historically low
rates of insurance coverage, the majority of adults who experience homelessness have
low rates of immunization coverage with vaccines routinely recommended for adults.
Community health centers provide preventive and primary health services to meet the
specific needs of persons experiencing homelessness, including vaccination. Street
or shelter-based interventions for targeted populations have been used as efficient
methods for vaccinating persons experiencing homelessness during outbreaks (
). Thirty-six states and the District of Columbia have expanded Medicaid under the
Affordable Care Act, providing an increase in coverage and access to care among persons
experiencing homelessness; an estimated 77% had access to some form of insurance in
This report provides recommendations for use of HepA vaccine among persons experiencing
homelessness and updates previous ACIP recommendations for HepA vaccine that did not
include homelessness as an indication for use of HepA vaccine for preexposure protection
against HAV infection (
During February 2018–October 2018, the ACIP Hepatitis Vaccines Work Group
held monthly conference calls to review and discuss relevant scientific evidence
supporting inclusion of homelessness as an indication for HepA vaccine. The work group
evaluated the quality of evidence related to the benefits and harms of administering
HepA vaccine to persons experiencing homelessness using the Grading of Recommendations
Assessment, Development and Evaluation (GRADE) framework (https://www.cdc.gov/vaccines/acip/recs/grade/table-refs.html).
At the October 2018 ACIP meeting, the following proposed recommendations were presented
to the committee: all persons aged 1 year and older experiencing homelessness should
be routinely immunized against hepatitis A. After a period for public comment, the
recommendations were approved unanimously by the voting ACIP members.**
Summary of Key Findings
Homelessness as an indication for hepatitis A vaccination. Little is known about HAV
seroprevalence among homeless populations in the United States. Review of the literature
found few studies that considered homelessness as an independent risk factor. Based
on the evidence to recommendations framework, other considerations were assessed,
such as recent HAV outbreaks (
), HAV-related hospitalizations and deaths, treatment costs for liver transplants,
and the benefits and costs associated with HepA vaccination (https://www.cdc.gov/vaccines/acip/recs/grade/table-refs.html).
These studies concluded that the benefits of vaccinating persons experiencing homelessness
were substantial and the cost and risk of vaccinating persons experiencing homelessness
is much lower than the risk of not vaccinating.
The clinical trial and observational studies that were included in the GRADE review
had several limitations, and some did not report any quantitative data. The studies
had limitations in design and execution. No comparison/control groups were present,
and there was a serious risk of bias, inconsistency, indirectness, and imprecision.
Only one study was found with vaccine immunogenicity data among the homeless population,
and it reported on a non-U.S. population.
GRADE quality of evidence summary for HepA vaccine among homeless persons. The evidence
assessing benefits and harms of administering HepA vaccine to prevent HAV infection
in persons experiencing homelessness was determined to be GRADE evidence type 4 (i.e.,
evidence from clinical experience and observations, observational studies with important
limitations, or randomized controlled trials with several major limitations) for benefits
and for harms. The balance of consequences for the evidence to recommendation framework
was determined to be that desirable consequences clearly outweigh undesirable consequences
in most settings (https://www.cdc.gov/vaccines/acip/recs/grade/table-refs.html).
Recommendation for Hepatitis A Vaccine for Persons Experiencing Homelessness
All persons aged 1 year and older experiencing homelessness should be routinely immunized
against hepatitis A (Box 1). Routine vaccination consists of a 2-dose schedule or
a 3-dose schedule when combined hepatitis A and B vaccine is administered.
Recommendations for routine preexposure use of hepatitis A vaccine — Advisory Committee
on Immunization Practices
All children at age 12–23 months.
Persons traveling to or working in countries that have high or intermediate HAV endemicity.
Persons who anticipate close contact with an international adoptee from a country
of high or intermediate endemicity during the first 60 days following arrival of
the adoptee in the United States.
Men who have sex with men.
Users of injection and noninjection drugs.
Persons with chronic liver disease.
Persons with clotting factor disorders.
Persons who work with HAV-infected primates or with HAV in a research laboratory setting.
Persons experiencing homelessness.
Anyone wishing to obtain immunity.
Sources: CDC. Prevention of hepatitis A through active or passive immunization: recommendations
of the Advisory Committee on Immunization Practices. MMWR Recomm Rep 2006;55(No. RR-7).
CDC. Updated recommendations from the Advisory Committee on Immunization Practices
(ACIP) for use of hepatitis A vaccine in close contacts of newly arriving international
adoptees. MMWR Morb Mortal Wkly Rep 2009;58:1006–7.
Nelson NP, Link-Gelles R, Hofmeister MG, et al. Update: recommendations of the Advisory
Committee on Immunization Practices for use of hepatitis a vaccine for postexposure
prophylaxis and for preexposure prophylaxis for international travel. MMWR Morb Mortal
Wkly Rep 2018;67:1216–20.
Concern about loss to follow-up before HepA vaccine series completion should not be
a deterrent to initiating the vaccine series in persons experiencing homelessness.
One dose of HepA vaccine provides personal protection and can contribute to herd immunity,
although long-term protection might be suboptimal (
Multiple definitions of homelessness have been published in the United States; however,
the definitions are similar in content. The U.S. Department of Health and Human Services
definition is used for the purpose of this recommendation (Box 2). Because of the
difficulty distinguishing the type of homelessness a person is experiencing (e.g.,
sheltered versus unsheltered) and the associated risks for HAV infection, all persons
experiencing homelessness should routinely receive HepA vaccine.
Homeless definition: U.S. Department of Health and Human Services
A homeless person is defined as an individual
who lacks housing (without regard to whether the individual is a member of a family),
including an individual whose primary residence during the night is a supervised public
or private facility (e.g., shelter) that provides temporary living accommodations
and an individual who is a resident in transitional housing;
without permanent housing who may live on the streets; stay in a shelter, mission,
single-room occupancy facility, abandoned building or vehicle; or in any other unstable
or nonpermanent situation;
who is “doubled up,” a term that refers to a situation where individuals are unable
to maintain their housing situation and are forced to stay with a series of friends
and/or extended family members.
In addition, previously homeless individuals who are to be released from a prison
or a hospital may be considered homeless if they do not have a stable housing situation
to which they can return. A recognition of the instability of an individual’s living
arrangements is critical to the definition of homelessness.
Sources: National Health Care for the Homeless Council. https://www.nhchc.org/faq/official-definition-homelessness/.
U.S. Department of Health and Human Services [Section 330 of the Public Health Service
Act (42 U.S.C., 254b)].
HRSA/Bureau of Primary Health Care, Program Assistance Letter 99–12, Health Care for
the Homeless Principles of Practice.
Rationale for Recommendation
Advantages of HepA vaccine for persons experiencing homelessness. Persons experiencing
homelessness might have difficulty implementing recommended nonvaccine strategies
to protect themselves from exposure (e.g., access to clean toilet facilities, regular
handwashing, and avoidance of crowded living conditions). For this reason, vaccination
is the most reliable protection from HAV infection for persons experiencing homelessness.
HepA vaccination of persons experiencing homelessness will provide individual protection
and increase herd immunity over time, reducing the risk of large-scale, person-to-person
outbreaks in this population. The recommendation facilitates routine HepA vaccination
of persons experiencing homelessness through facilities that already provide health
care services for the homeless population.
What is already known about this topic?
Hepatitis A (HepA) vaccine is highly safe and effective, and a complete HepA vaccine
series provides long-term protection against hepatitis A virus (HAV) infection. Person-to-person
HAV outbreaks among persons using drugs or experiencing homelessness are widespread
What is added by this report?
All persons aged ≥1 year experiencing homelessness should be routinely immunized against
HAV. Vaccination of homeless persons facilitates integration of HepA vaccine into
routine preventive services.
What are the implications for public health practice?
HepA vaccination of homeless persons would improve protection of persons at increased
risk of exposure to HAV and complications of hepatitis A disease and reduce the risk
for large-scale outbreaks by increasing immunity to HAV among homeless persons living
in congregate settings where HAV can spread readily.