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      Vaccination Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten — United States, 2018–19 School Year

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          State and local school vaccination requirements exist to ensure that students are protected against vaccine-preventable diseases ( 1 ). This report summarizes data collected by state and local immunization programs* on vaccination coverage among children in kindergarten in 49 states, exemptions for kindergartners in 50 states, and provisional enrollment and grace period status for kindergartners in 30 states. Nationally, vaccination coverage † was 94.9% for the state-required number of doses of diphtheria and tetanus toxoids, and acellular pertussis vaccine (DTaP); 94.7% for 2 doses of measles, mumps, and rubella vaccine (MMR); and 94.8% for the state-required doses of varicella vaccine. Whereas 2.5% of kindergartners had an exemption from at least one vaccine, § 2.8% of kindergartners were not up to date for MMR and did not have a vaccine exemption. Nearly all states could achieve the recommended ≥95% MMR coverage if all nonexempt kindergartners were vaccinated in accordance with local and state vaccination policies. In accordance with state and local school entry requirements, parents and guardians submit children’s vaccination records or exemption forms to schools, or schools obtain records from state immunization information systems. Federally funded immunization programs collaborate with departments of education, school nurses, and other school personnel to assess vaccination coverage and exemption status of children enrolled in public and private kindergartens and to report unweighted counts, aggregated by school type, to CDC via a web-based questionnaire in the Secure Access Management System. ¶ CDC uses these counts to produce state-level and national-level estimates of vaccination coverage. During the 2018–19 school year, 49 states reported coverage for all state-required vaccines among public school kindergartners; 48 states reported on private school kindergartners.** All 50 states reported exemption data among public school kindergartners; 49 states reported on private school kindergartners. Overall national and median vaccination coverage for the state-required number of doses of DTaP, MMR, and varicella vaccine are reported. Coverage with hepatitis B and poliovirus vaccines, which are required in most states but not included in this report, are available at SchoolVaxView ( 2 ). Thirty states reported data on kindergartners who, at the time of assessment, attended school under a grace period (attendance without proof of complete vaccination or exemption during a set interval) or provisional enrollment (school attendance while completing a catch-up vaccination schedule). Coverage and exemptions from the U.S. territories and affiliated jurisdictions are included in this report; however, national estimates, medians, and summary measures include only U.S. states. Vaccination coverage and exemption estimates were adjusted according to survey type and response rates. †† For the 2018–19 school year, CDC is reporting national-level estimates alongside the state-level median estimates. The national estimates complement the medians by addressing the limitation that the median estimates weight every state equally regardless of population size. Reported estimates for the 2018–19 school year are based on 3,634,896 kindergartners surveyed for vaccination coverage, 3,643,598 for exemptions, and 2,813,482 for grace period and provisional enrollment among the 4,001,404 children reported as enrolled in kindergarten by the 50 state immunization programs. §§ Potentially achievable coverage with MMR, defined as the sum of the percentage of children up to date with 2 doses of MMR and those with no documented vaccination exemption but not up date, was calculated for each state. Nonexempt students include those provisionally enrolled, in a grace period, or otherwise without documentation of vaccination. SAS (version 9.4; SAS Institute) was used for all analyses. Vaccination assessments varied by immunization program because of differences in states’ required vaccines and doses, vaccines assessed, methods, and data reported (Supplementary Table 1, https://stacks.cdc.gov/view/cdc/81811). Most states reported kindergartners as up to date for a given vaccine if they had received all doses of that vaccine required for school entry, ¶¶ except seven states*** that reported kindergartners as up to date for any given vaccine only if they had received all doses of all vaccines required for school entry. Nationally, 2-dose MMR coverage was 94.7% (range = 87.4% [Colorado] to ≥99.2% [Mississippi]). Coverage of ≥95% was reported by 20 states and coverage of <90% by two (Table). DTaP coverage was 94.9% (range = 88.8% [Idaho] to ≥99.2% [Mississippi]). Coverage of ≥95% was reported by 21 states, and coverage of <90% by one. Varicella vaccine coverage was 94.8% (range=86.5% [Colorado] to ≥99.2% [Mississippi]), with 20 states reporting coverage ≥95%, and four reporting <90% coverage. TABLE Estimated* vaccination coverage † for measles, mumps, and rubella vaccine (MMR), diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP), and varicella vaccine, grace period or provisional enrollment, § and any exemption ¶ among children enrolled in kindergarten, by immunization program — United States, territories, and associated states, 2018–19 school year Immunization program Kindergarten population** No. (%) surveyed†† MMR, 
2 doses (%)§§ DTaP, 
5 doses (%)¶¶ Varicella, 2 doses (%)*** Grace period or provisional enrollment (%) Any exemption (%) Percentage point change in any exemption from 2017 to 2018 National estimate††† 4,001,404 3,634,896 94.7 94.9 94.8 2.0 2.5 0.2 Median††† Not applicable Not applicable 94.2 94.6 94.3 1.8 2.6 0.4 State Alabama§§§,¶¶¶ 77,739 77,739 (100.0) ≥90.6 ≥90.6 ≥90.6 NP 0.8 −0.1 Alaska¶¶¶,**** 10,316 8,702 (84.4) NR NR NR NR 7.1 0.1 Arizona§§§,†††† 79,981 79,981 (100.0) 92.9 92.7 95.6 NR 6.0 0.2 Arkansas§§§§ 39,257 37,466 (95.4) 94.2 93.4 93.8 4.5 1.8 0.1 California¶¶¶,††††,§§§§ 568,947 555,735 (97.7) 96.5 96.0 97.9 1.7 0.6 −0.1 Colorado§§§,¶¶¶¶ 64,191 64,191 (100.0) 87.4 90.3 86.5 0.6 4.9 0.2 Connecticut§§§,¶¶¶ 38,230 38,230 (100.0) 95.9 96.1 95.7 NP 2.7 0.4 Delaware¶¶¶ 10,798 1,021 (9.5) 97.8 97.8 97.6 NR 1.2 −0.2 District of Columbia**** NA NA NR NR NR NR NR NA Florida§§§,¶¶¶,***** 224,641 224,641 (100.0) ≥93.8 ≥93.8 ≥93.8 2.9 3.2 0.3 Georgia§§§,¶¶¶ 131,275 131,275 (100.0) ≥93.6 ≥93.6 ≥93.6 0.2 2.5 −0.2 Hawaii¶¶¶ 16,051 1,081 (6.6) 91.5 92.4 94.0 1.3 4.4 1.3 Idaho 22,995 22,769 (99.0) 89.5 88.8 88.3 2.2 7.7 0.6 Illinois§§§,¶¶¶¶ 143,876 143,876 (100.0) 94.7 94.7 94.4 1.1 1.8 0.2 Indiana¶¶¶ 82,324 79,350 (96.4) 91.2 94.4 93.5 NR 1.3 0.4 Iowa§§§,¶¶¶ 40,624 40,624 (100.0) ≥93.3 ≥93.3 ≥93.3 3.0 2.4 0.4 Kansas¶¶¶,§§§§,††††† 37,838 8,744 (23.1) 90.8 91.0 89.2 NR 2.1 0.4 Kentucky¶¶¶,§§§§,***** 55,587 55,024 (99.0) 93.4 94.1 92.8 NR 1.4 0.0 Louisiana§§§ 56,203 56,203 (100.0) 95.5 97.7 95.4 NA 1.2 0.1 Maine 13,419 12,875 (95.9) 93.8 94.5 95.9 NR 6.2 0.9 Maryland¶¶¶,§§§§ 71,431 71,423 (100.0) 97.4 97.7 97.1 NR 1.5 0.1 Massachusetts§§§,¶¶¶,§§§§ 65,279 65,279 (100.0) 96.9 97.1 96.5 NP 1.4 0.1 Michigan§§§ 118,632 118,632 (100.0) 94.6 94.8 94.3 0.6 4.5 0.3 Minnesota¶¶¶¶,***** 70,085 68,779 (98.1) 92.6 92.5 92.0 NR 3.7 0.2 Mississippi§§§,¶¶¶,†††† 37,775 37,775 (100.0) ≥99.2 ≥99.2 ≥99.2 0.6 0.1 0.0 Missouri§§§,¶¶¶¶ 72,687 72,687 (100.0) 94.8 94.8 94.5 NR 2.7 0.4 Montana§§§,¶¶¶ 12,480 12,480 (100.0) 93.3 93.0 92.9 1.9 4.5 0.2 Nebraska¶¶¶,§§§§, 26,925 26,548 (98.6) 96.9 97.4 96.3 1.3 2.1 −0.1 Nevada¶¶¶ 37,971 1,811 (4.8) 95.1 95.0 94.7 1.0 3.3 0.1 New Hampshire¶¶¶ 12,421 12,421 (100.0) ≥91.8 ≥91.8 ≥91.8 4.9 3.3 0.4 New Jersey§§§,¶¶¶ 109,161 109,161 (100.0) ≥95.0 ≥95.0 ≥95.0 1.1 2.5 0.3 New Mexico¶¶¶ 25,269 25,170 (99.6) 96.1 96.0 95.7 1.9 1.5 −0.2 New York (including New York City)§§§,¶¶¶ 220,495 220,495 (100.0) 97.2 96.7 96.7 1.9 1.3 0.2 New York City§§§,¶¶¶ 96,912 96,912 (100.0) 97.7 97.0 97.1 1.2 0.7 0.0 North Carolina¶¶¶,§§§§,***** 124,343 113,074 (90.9) 93.2 93.2 93.1 1.6 1.6 −0.4 North Dakota 10,382 10,315 (99.4) 93.6 93.6 93.8 NR 4.3 0.9 Ohio 139,679 132,589 (94.9) 91.6 91.9 91.2 6.7 2.9 0.3 Oklahoma***** 54,806 50,456 (92.1) 92.2 92.7 95.8 NR 2.6 0.4 Oregon§§§, §§§§ 45,870 45,870 (100.0) 93.0 92.4 94.3 NR 7.7 0.1 Pennsylvania 143,560 133,945 (93.3) 96.4 96.6 95.8 2.6 2.9 0.1 Rhode Island§§§,¶¶¶,§§§§,***** 10,964 10,964 (100.0) 97.4 97.4 97.0 NR 1.3 0.2 South Carolina¶¶¶ 58,442 15,797 (27.0) 94.2 94.6 93.5 0.9 2.6 0.6 South Dakota¶¶¶ 12,062 12,052 (99.9) 96.2 95.8 95.5 NR 2.6 0.4 Tennessee§§§,¶¶¶,§§§§ 78,630 78,630 (100.0) 96.5 96.2 96.2 1.6 1.9 0.4 Texas (including Houston)§§§§,***** 390,034 387,530 (99.4) 96.9 96.7 96.5 1.5 2.4 0.4 Houston§§§§,***** 37,897 37,675 (99.4) 96.6 96.6 95.9 1.4 1.5 0.3 Utah§§§ 50,179 50,179 (100.0) 92.8 92.4 92.5 2.3 5.7 0.4 Vermont§§§,¶¶¶ 6,126 6,126 (100.0) 93.0 92.9 92.3 5.1 4.7 0.9 Virginia¶¶¶,††††† 100,394 4,422 (4.4) 95.0 98.0 93.6 NR 1.7 0.2 Washington***** 87,510 84,771 (96.9) 90.8 90.8 89.7 1.7 5.0 0.3 West Virginia¶¶¶,††††,§§§§§ 19,442 15,426 (79.3) 98.8 98.7 98.5 2.3 0.8 0.6 Wisconsin§§§§,*****,††††† 66,344 1,530 (2.3) 92.6 96.2 91.6 4.9 5.9 0.5 Wyoming 7,734 7,734 (100.0) 95.1 95.3 94.7 2.5 2.9 NA Territories and associated states American Samoa¶¶¶ NA NA NA NA NReq NP NA NA Federated States of Micronesia§§§ 1,786 1,786 (100.0) 91.3 80.2 NReq NR 0.0 0.0 Guam¶¶¶ 2,563 735 (28.7) 88.4 90.7 NReq NR 0.1 -0.3 Marshall Islands§§§,¶¶¶,†††† 1,114 1,114 (100.0) 95.1 83.8 NReq NR 0.0 0.0 Northern Mariana Islands§§§ 812 812 (100.0) 97.7 79.4 98.2 NR 0.0 0.0 Palau§§§,¶¶¶¶¶ 304 304 (100.0) 100.0 100.0 NReq NR 0.0 0.0 Puerto Rico 26,353 1,545 (5.9) 94.7 91.4 94.7 NR 1.6 NA U.S. Virgin Islands NA NA NA NA NA NA NA NA Abbreviations: NA = not available; NP = no grace period/provisional policy; NR = not reported to CDC; NReq = not required. * Estimates are adjusted for nonresponse and weighted for sampling where indicated. † Estimates based on a completed vaccine series (i.e., not vaccine-specific) use the “≥” symbol. Coverage might include history of disease or laboratory evidence of immunity. § A grace period is a set number of days during which a student can be enrolled and attend school without proof of complete vaccination or exemption. Provisional enrollment allows a student without complete vaccination or exemption to attend school while completing a catch-up vaccination schedule. In states with one or both of these policies, the estimates represent the number of kindergartners within a grace period, provisionally enrolled, or some combination of these categories. ¶ Exemptions, grace period, provisional enrollment, and vaccine coverage status might not be mutually exclusive. Some children enrolled under a grace period or provisional enrollment might be exempt from one or more vaccinations, while children with exemptions might be fully vaccinated with one or more required vaccines. ** The kindergarten population is an approximation provided by each program. The national total excludes the 8,075 kindergartners from the District of Columbia for which data were not reported. †† The number surveyed represents the number of kindergartners surveyed for vaccination coverage. For Alaska, this number represents the number surveyed for exemptions because coverage was not reported. The national total excludes the 8,702 kindergartners from Alaska. Exemption estimates are based on 31,792 kindergartners for Kansas, 95,875 kindergartners for Virginia, and 66,652 kindergartners for Wisconsin. §§ Most states require 2 doses of MMR; Alaska, New Jersey, and Oregon require 2 doses of measles, 1 dose of mumps, and 1 dose of rubella vaccines. Georgia, New York, New York City, North Carolina, and Virginia require 2 doses of measles and mumps, 1 dose of rubella vaccines. Iowa requires 2 doses of measles and 2 doses of rubella vaccines. ¶¶ Pertussis vaccination coverage might include some diphtheria, tetanus toxoids, and pertussis vaccine (DTP) vaccinations if administered in another country or by a vaccination provider who continued to use DTP after 2000. Most states require 5 doses of DTaP for school entry, or 4 doses if the 4th dose was received on or after the 4th birthday; Illinois, Maryland, Virginia, and Wisconsin require 4 doses; Nebraska requires 3 doses. The reported coverage estimates represent the percentage of kindergartners with the state-required number of DTaP doses, except for Kentucky, which requires ≥5 doses but reports ≥4 doses of DTaP. *** Most states require 2 doses of varicella vaccine for school entry; Alabama, Arizona, California, Hawaii, Maine, New Jersey, Oklahoma, and Oregon require 1 dose. Reporting of varicella vaccination status for kindergartners with a history of varicella disease varied within and among states; some were reported as vaccinated against varicella and others as medically exempt. ††† National coverage estimates and medians calculated from data from 49 states (i.e., does not include Alaska). National grace period or provisional enrollment estimate and median were calculated from data from 30 states that have either a grace period or provisional enrollment policy and reported relevant data to CDC. National exemption estimate and median were calculated from data from 50 states. Other jurisdictions excluded were Houston, Texas, New York City, American Samoa, Guam, Marshall Islands, Federated States of Micronesia, Northern Mariana Islands, Palau, Puerto Rico, and U.S. Virgin Islands. Data reported from 3,634,896 kindergartners assessed for coverage, 3,643,598 for exemptions and 2,813,482 for grace period/provisional enrollment. Estimates represent rates for populations of 3,991,088; 4,001,404; and 3,025,009 kindergartners for coverage, exemptions and grace period/provisional enrollment, respectively. §§§ The proportion surveyed likely was <100% but is reported as 100% based on incomplete information about the actual current enrollment. ¶¶¶ Philosophical exemptions were not allowed. **** Kindergarten vaccination coverage (Alaska and District of Columbia) and exemption data (District of Columbia) were not reported because of problems with data collection. †††† Religious exemptions were not allowed. §§§§ Counted some or all vaccine doses received regardless of Advisory Committee on Immunization Practices recommended age and time interval; vaccination coverage rates reported might be higher than those for valid doses. ¶¶¶¶ Program did not report the number of children with exemptions, but instead reported the number of exemptions for each vaccine, which could count some children more than once. Lower bounds of the percentage of children with any exemptions were estimated using the individual vaccines with the highest number of exemptions. ***** Did not include some types of schools, such as online schools or those located on military bases, in correctional facilities, or on tribal lands. ††††† Kindergarten vaccination coverage data were collected from a sample, and exemption data were collected from a census of kindergartners. §§§§§ Reported public school data only. ¶¶¶¶¶ For Palau, estimates represent coverage among children in first grade. The percentage of kindergartners with an exemption from one or more required vaccines (not limited to MMR, DTaP, and varicella vaccines) was 2.5% in 2018–19 (range = 0.1% [Mississippi] to 7.7% [Idaho and Oregon]). This is slightly higher than the 2.3% during the 2017–18 school year and 2.1% in 2016–17. (Table) (Figure 1). Nationally, 0.3% of kindergartners had a medical exemption, and 2.2% had a nonmedical exemption (Supplementary Table 2, https://stacks.cdc.gov/view/cdc/81810). FIGURE 1 Estimated national percentage exempt and range of states’ exemptions from one or more vaccines among kindergartners — United States, 2013–14 to 2018–19 school years The figure is a line chart showing estimated national percentage exempt and range of states’ exemptions from one or more vaccines among kindergartners in the United States during the 2013–14 to 2018–19 school years. The percentage of kindergartners attending school within a grace period or provisionally enrolled among the 30 states reporting these data was 2.0% (range = 0.2% [Georgia] to 6.7% [Ohio]) (Table). In 10 of these states, the percentage of children provisionally enrolled or within a grace period at the time of assessment exceeded the percentage of children with exemptions from one or more vaccines. Forty-four states could potentially achieve ≥95% MMR coverage if all nonexempt kindergartners, many of whom are within a grace period or provisionally enrolled, were vaccinated (Figure 2). Follow-up could assure all missing vaccinations are completed and all missing documentation of vaccination is provided to schools. FIGURE 2 Potentially achievable coverage* ,†,§ with measles, mumps, and rubella vaccine (MMR) among kindergartners — 49 states, 2018–2019 school year * Potentially achievable coverage is estimated as the sum of the percentage of students with up-to-date MMR and the percentage of students without up-to-date MMR and without a vaccine exemption. † The exemptions used to calculate the potential increase in MMR coverage for Arizona, Arkansas, Colorado, Idaho, Illinois, Maine, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, Texas, Utah, Vermont, and Wyoming are the number of children with exemptions specifically for MMR vaccine. For all other states, numbers are based on an exemption to any vaccine. § Alaska and the District of Columbia did not report kindergarten vaccination coverage for the 2018–19 school year and are excluded from this analysis. The figure is a stacked bar chart showing potentially achievable coverage with measles, mumps, and rubella vaccine among kindergartners in 49 states during the 2018–2019 school year. Discussion Measles outbreaks affecting school-age children across multiple states during the 2018–19 school year underscore the importance of both school vaccination requirements for preventing disease spread and school coverage assessments to identify pockets of undervaccination ( 3 ). During the 2018–19 school year, national coverage with MMR, DTaP, and varicella vaccines remained near 95% ( 2 , 4 ). However, coverage and exemption rates varied by state. Recent measles outbreaks in states with high overall MMR coverage, such as New York, highlight the need for assessing vaccination coverage at the local level. CDC encourages programs to use their local-level school assessment data to identify populations of undervaccinated students and to partner with schools and providers to reduce barriers to vaccination and improve coverage. Although the overall percentage of children with an exemption increased slightly for the second consecutive school year, children with exemptions still represent a small proportion of kindergartners nationally and in most states. More importantly, in 25 states, the number of nonexempt undervaccinated kindergartners exceeded the number of those with exemptions. In many states, nonexempt undervaccinated students are attending school in a grace period or are provisionally enrolled. Fifteen states allow grace periods, with 30 days the most common length, and 47 states allow provisional enrollment for students in the process of completing the vaccination schedule (R McCord, CDC, unpublished data, 2019). Follow-up with parents of these students to verify that vaccinations and related documentation are complete typically falls to school nurses or other school staff members (R Seither, CDC, unpublished data, 2019). The California Department of Public Health’s immunization program collaborated with the state Department of Education and with individual schools to reduce provisional enrollment substantially over several years, which resulted in measurable increases in vaccination coverage, through training on the correct application of the relevant rules so that only those children who were completing a catch-up schedule were provisionally enrolled, and audits to assess the implementation by school staff members ( 5 , 6 ). Almost all states could achieve ≥95% MMR coverage if undervaccinated nonexempt children were vaccinated in accordance with local and state vaccination policies. The findings in this report are subject to at least five limitations. First, comparability is limited because of variation in states’ requirements, data collection methods, and definitions of grace period and provisional enrollment. Second, representativeness might be negatively affected because of data collection methods that miss some schools or students, such as homeschooled students, or assess vaccination status at different times. Third, actual vaccination coverage, exemption rates, or both might be underestimated or overestimated because of inaccurate or absent documentation or missing schools. Fourth, national coverage estimates include only 49 of 50 states, exemption estimates include all states but use lower-bound estimates for four states, and grace period or provisional enrollment estimates include only 30 states for the 2018–19 school year. Finally, because most states do not report vaccine-specific exemptions, estimates of potentially achievable MMR coverage are approximations. However, if reported exemptions were for a vaccine or vaccines other than MMR, potentially achievable MMR coverage would be higher than that presented. Kindergarten vaccination requirements help ensure that students are fully vaccinated with recommended vaccines upon school entry. CDC works with immunization programs to collect and report data on school vaccination coverage, exemption rates, and grace period and provisional enrollment each year. Immunization programs can use these data to identify schools and communities with high concentrations of undervaccinated students and inform strategies to increase vaccination coverage. Such strategies include education campaigns to counteract misinformation in areas with high numbers of vaccine exemptions and increased follow-up of undervaccinated students without exemptions to ensure these children are vaccinated in accordance with local and state vaccination policies ( 7 ) to reduce the risk for transmission of vaccine-preventable diseases. Summary What is already known about this topic? State immunization programs conduct annual kindergarten vaccination assessments to monitor school-entry vaccination coverage with all state-required vaccines. What is added by this report? For the 2018–19 school year, coverage was 94.7% for 2 doses of measles, mumps, and rubella vaccine (MMR) and 94.9% for the state-required number of doses of diphtheria and tetanus toxoids and acellular pertussis vaccine, and 94.8% for varicella vaccine. Although the exemption rate slightly increased to 2.5%, most states could achieve the recommended ≥95% MMR coverage if undervaccinated children without an exemption were completely vaccinated. What are the implications for public health practice? State and local immunization programs can use school coverage assessments to detect pockets of undervaccination and guide strategies to increase vaccination coverage.

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          Vaccine refusal, mandatory immunization, and the risks of vaccine-preventable diseases.

          Vaccines are among the most effective prevention tools available to clinicians. However, the success of an immunization program depends on high rates of acceptance and coverage. There is evidence of an increase in vaccine refusal in the United States and of geographic clustering of refusals that results in outbreaks. Children with exemptions from school immunization requirements (a measure of vaccine refusal) are at increased risk for measles and pertussis and can infect others who are too young to be vaccinated, cannot be vaccinated for medical reasons, or were vaccinated but did not have a sufficient immunologic response. Clinicians can play a crucial role in parental decision making. Health care providers are cited as the most frequent source of immunization information by parents, including parents of unvaccinated children. Although some clinicians have discontinued or have considered discontinuing their provider relationship with patients who refuse vaccines, the American Academy of Pediatrics Committee on Bioethics advises against this and recommends that clinicians address vaccine refusal by respectfully listening to parental concerns and discussing the risks of nonvaccination. 2009 Massachusetts Medical Society
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            Vaccination Coverage for Selected Vaccines and Exemption Rates Among Children in Kindergarten — United States, 2017–18 School Year

            State and local school vaccination requirements exist to ensure that students are protected from vaccine-preventable diseases ( 1 ). This report summarizes vaccination coverage and exemption estimates collected by state and local immunization programs* for children in kindergarten (kindergartners) in 49 states and the District of Columbia (DC) and kindergartners provisionally enrolled (attending school without complete vaccination or exemption while completing a catch-up vaccination schedule) or in a grace period (a set interval during which a student may be enrolled and attend school without proof of complete vaccination or exemption) for 28 states. Median vaccination coverage † was 95.1% for the state-required number of doses of diphtheria and tetanus toxoids, and acellular pertussis vaccine (DTaP); 94.3% for 2 doses of measles, mumps, and rubella vaccine (MMR); and 93.8% for 2 doses of varicella vaccine. The median percentage of kindergartners with an exemption from at least one vaccine § was 2.2%, and the median percentage provisionally enrolled or attending school during a grace period was 1.8%. Vaccination coverage among kindergartners remained high; however, schools can improve coverage by following up with students who are provisionally enrolled, in a grace period, or lacking complete documentation of required vaccinations. Federally funded immunization programs collaborate with departments of education, school nurses, and other school personnel to assess vaccination coverage and exemption status of children enrolled in public and private kindergartens. ¶ In accordance with state and local school entry requirements, parents and guardians submit children’s vaccination records or exemption forms to schools, or schools obtain records from state immunization information systems. During the 2017–18 school year, 49 states and DC reported coverage for all state-required vaccines and exemption data among public school kindergartners; 48 states and DC reported on private school kindergartners.** Median vaccination coverage for the state-required number of doses of DTaP, 2 doses of MMR, and 2 doses of varicella vaccine are reported. Coverage with hepatitis B and poliovirus vaccines, which are required in most states but not included in this report, are presented on SchoolVaxView ( 2 ). Twenty-eight states reported data on kindergartners who, at the time of assessment, attended school under a grace period or provisional enrollment. Immunization programs in U.S. territories also receive public funding for immunization and report vaccination coverage and exemptions to CDC; however, national medians and summary measures reported here include only the U.S. states and DC. Vaccination coverage and exemption estimates were adjusted according to survey type and response rates. †† During the 2017–18 school year, vaccination coverage data were reported for approximately 3,988,127 kindergartners, exemption data for approximately 3,634,631, and grace period and provisional enrollment data for approximately 2,825,691. §§ Potentially achievable coverage for MMR was calculated for each state as the percentage of students vaccinated with 2 doses of MMR plus the percentage without 2 doses of MMR and no documented vaccination exemption. Nonexempt students included those provisionally enrolled, in a grace period, or otherwise without documentation of vaccination. During the 2017–18 school year, vaccination assessments varied by immunization program because of differences in states’ required vaccines and doses, vaccines assessed, assessment methods, and data reported. Among the 49 states and DC reporting kindergarten vaccination data, 36 used a census; nine used a sample; three used a voluntary school response; and two used a mix of sampling methods. ¶¶ All states used the same methods to collect both vaccination coverage and exemption data except Alaska, Kansas, Virginia, and Wisconsin, where a sample was used for vaccination coverage data and a census for exemption data. Kindergartners were considered up to date and included in the coverage estimate for a given vaccine if they received all doses required for school entry,*** except in seven states ††† that considered kindergartners up to date only if they received all doses of all vaccines required for school entry. Reporting of varicella vaccination status among kindergartners with a history of varicella disease varied within and among states; some were reported as vaccinated against varicella and others as medically exempt. Among the 49 states and DC included in this analysis, median 2-dose MMR coverage was 94.3% (range = 81.3% [DC] to ≥99.4% [Mississippi]), 23 states reported coverage ≥95%, and three states and DC reported coverage <90% (Table 1). Median DTaP coverage was 95.1% (range = 79.7% [DC] to ≥99.4% [Mississippi]), 25 states reported coverage ≥95%, and three states and DC reported coverage <90%. Among the 41 states and DC that required and reported 2 doses of varicella vaccine, median coverage was 93.8% (range = 80.5% [DC] to ≥99.4% [Mississippi]), 17 states reported coverage ≥95%, and four states and DC reported coverage <90%. TABLE 1 Estimated vaccination coverage* for MMR, DTaP, and varicella vaccines among children enrolled in kindergarten, by vaccine and immunization program — United States and territories, 2017–18 school year Immunization program Kindergarten population† No. (%) surveyed Type of survey conducted§ Local data available online¶ MMR** DTaP†† Varicella 2 doses (%) 4 or 5 doses (%) 1 dose (%) 2 doses (%) Median§§ 94.3 95.1 96.2 93.8 Alabama¶¶ 57,245 57,245 (100.0) Census Yes ≥92.7 ≥92.7 ≥92.7 NReq Alaska***,††† 9,692 707 (7.3) Stratified 2-stage cluster sample No 91.6 91.1 NA 91.3 Arizona¶¶ 81,710 81,710 (100.0) Census Yes 93.4 93.5 96.2 NReq Arkansas§§§ 39,630 38,242 (96.5) Census (public), voluntary response (private) No 91.9 91.3 NA 91.6 California§§§ 574,702 564,121 (98.2) Census Yes 96.9 96.4 98.2 NReq Colorado¶¶ 65,718 65,718 (100.0) Census Yes 88.7 88.6 NA 87.7 Connecticut¶¶ 39,174 39,174 (100.0) Census No 96.5 96.5 NA 96.3 Delaware 10,988 1,053 (9.6) Stratified 2-stage cluster sample No 96.7 96.9 NA 96.7 District of Columbia¶¶ 8,205 8,205 (100.0) Census No 81.3 79.7 NA 80.5 Florida¶¶,*** 222,397 222,397 (100.0) Census Yes ≥93.7 ≥93.7 NA ≥93.7 Georgia¶¶ 131,459 131,459 (100.0) Census No ≥93.4 ≥93.4 NA ≥93.4 Hawaii 16,325 1,040 (6.4) Stratified 2-stage cluster sample No 95.6 95.4 96.2 NReq Idaho 22,553 22,458 (99.6) Census Yes 89.5 89.3 NA 88.6 Illinois¶¶ 144,858 144,858 (100.0) Census Yes 95.2 95.3 NA 94.8 Indiana 84,296 70,857 (84.1) Voluntary response Yes 90.4 94.3 NA 90.2 Iowa¶¶ 39,632 39,632 (100.0) Census Yes ≥93.0 ≥93.0 NA ≥93.0 Kansas***,†††,§§§ 38,484 8,728 (22.7) Stratified 2-stage cluster sample Yes 89.1 89.5 NA 88.3 Kentucky***,§§§ 55,152 50,538 (91.6) Census Yes 92.6 93.7 NA 91.7 Louisiana¶¶ 58,277 58,277 (100.0) Census Yes 96.1 97.7 NA 95.6 Maine 13,255 12,527 (94.5) Census Yes 94.3 95.3 96.5 NReq Maryland§§§ 68,528 67,747 (98.9) Census No 98.6 99.0 NA 98.6 Massachusetts¶¶,§§§ 63,377 63,377 (100.0) Census Yes 96.3 96.4 NA 96.0 Michigan¶¶ 119,028 119,028 (100.0) Census Yes 95.0 95.3 NA 94.7 Minnesota*** 69,807 67,372 (96.5) Census Yes 92.5 92.8 NA 92.2 Mississippi¶¶ 39,284 39,284 (100.0) Census Yes ≥99.4 ≥99.4 NA ≥99.4 Missouri¶¶ 73,113 73,113 (100.0) Census No 95.2 95.3 NA 95.0 Montana¶¶ 12,188 12,188 (100.0) Census No 93.2 92.6 NA 91.6 Nebraska§§§ 26,313 25,796 (98.0) Census No 96.2 96.7 NA 95.5 Nevada 37,178 1,769 (4.8) Stratified 2-stage cluster sample No 93.0 92.6 NA 92.6 New Hampshire 12,165 11,939 (98.1) Census No ≥92.4 ≥92.4 NA ≥92.4 New Jersey¶¶ 107,630 107,630 (100.0) Census Yes ≥96.1 ≥96.1 ≥96.1 NReq New Mexico 26,896 1,256 (4.7) Stratified 2-stage cluster sample No 94.8 94.9 NA 94.5 New York (including New York City)¶¶ 226,456 226,456 (100.0) Census Yes 97.2 96.9 NA 96.9 New York City¶¶ 100,466 100,466 (100.0) Census No 97.8 97.3 NA 97.4 North Carolina***,§§§ 127,197 120,827 (95.0) Census No 97.0 96.8 NA 96.8 North Dakota 10,365 10,293 (99.3) Census Yes 94.2 94.1 NA 93.9 Ohio 138,753 132,763 (95.7) Census No 92.1 92.1 NA 91.5 Oklahoma*** 53,898 48,481 (89.9) Census (public), voluntary response (private) No 92.6 93.9 96.8 NReq Oregon¶¶,§§§ 45,818 45,818 (100.0) Census Yes 93.2 92.4 94.4 NReq Pennsylvania 141,571 123,377 (87.1) Voluntary response Yes 96.7 97.0 NA 97.0 Rhode Island¶¶,***,§§§ 11,025 11,025 (100.0) Census Yes 96.4 96.2 NA 96.0 South Carolina 58,458 16,174 (27.7) Stratified 1-stage cluster sample No 96.3 96.6 NA 96.1 South Dakota 12,125 12,112 (99.9) Census Yes 96.6 95.9 NA 95.8 Tennessee¶¶,*** 78,743 78,743 (100.0) Census Yes 96.9 96.7 NA 96.8 Texas (including Houston)***,§§§ 387,981 378,008 (97.4) Census Yes 96.9 96.8 NA 96.4 Houston***,§§§ 43,340 38,343 (88.5) Voluntary response (public), Census (private) No 95.1 95.2 NA 94.7 Utah¶¶ 48,827 48,827 (100.0) Census Yes 93.4 93.2 NA 93.7 Vermont¶¶ 6,255 6,255 (100.0) Census Yes 94.1 94.0 NA 93.2 Virginia††† 100,581 4,224 (4.2) Stratified 2-stage cluster sample Yes 95.5 98.2 NA 93.3 Washington*** 85,118 79,977 (94.0) Census Yes 90.6 90.7 NA 89.4 West Virginia**** 19,519 15,120 (77.5) Voluntary response Yes 98.4 98.0 NA 98.1 Wisconsin***,†††,§§§ 66,178 1,223 (1.8) Stratified 2-stage cluster sample No 91.8 96.5 NA 91.2 Wyoming NA NA Not conducted No NA NA NA NA Territories and associated states American Samoa¶¶,**** 758 758 (100.0) Census No 90.9 81.8 NReq NReq Federated States of Micronesia¶¶ 1,886 1,886 (100.0) Census No 94.0 75.8 NReq NReq Guam 2,625 700 (26.7) Stratified 2-stage cluster sample No 85.0 92.0 NReq NReq Marshall Islands¶¶ 1,086 1,086 (100.0) Census No 96.6 67.7 NReq NReq Northern Mariana Islands¶¶ 876 876 (100.0) Census No 92.8 75.6 NA 92.6 Palau¶¶,¶¶¶ 313 313 (100.0) Census No 100.0 100.0 NReq NReq Puerto Rico†††† NA NA Not conducted No NA NA NA NA U.S. Virgin Islands†††† NA NA Not conducted No NA NA NA NA Abbreviations: DTaP/DT = diphtheria and tetanus toxoids (DT) and acellular pertussis vaccine; MMR = measles, mumps, and rubella vaccine; NA = not available; NReq = not required for school entry. * Estimates are adjusted for nonresponse and weighted for sampling where appropriate. Estimates based on a completed vaccine series (i.e., not vaccine-specific) use the “≥” symbol. Coverage might include history of disease or laboratory evidence of immunity. † The kindergarten population is an approximation provided by each program. § Sample designs varied by state or area: census = program attempted to include all schools (public and private) and all children within schools in the assessment and had a student response rate of ≥90%; 1-stage or 2-stage cluster sample = schools were randomly selected, and all children in the selected schools were assessed (1-stage), or a random sample of children within the schools was selected (2-stage); voluntary response = a census with a student response rate of <90% (does not imply that participation was optional). ¶ Some programs publish kindergarten vaccination data online that are more detailed than the state-level estimates in this table. Examples of more detailed data include county, parish, school district, and school-level estimates. ** Most states require 2 doses of MMR; Alaska, New Jersey, and Oregon require 2 doses of measles, 1 dose of mumps, and 1 dose of rubella vaccines. Georgia, New York, New York City, North Carolina, and Virginia require 2 doses of measles and mumps and 1 dose of rubella vaccines. Iowa requires 2 doses of measles and 2 doses of rubella vaccines. †† Pertussis vaccination coverage might include some diphtheria, tetanus toxoids, and pertussis vaccine (DTP) vaccinations if administered in another country or by a vaccination provider who continued to use DTP after 2000. Most states require 5 doses of DTaP for school entry, or 4 doses if the fourth dose was received on or after the fourth birthday; Illinois, Maryland, Virginia, and Wisconsin require 4 doses; Nebraska requires 3 doses. The reported coverage estimates represent the percentage of kindergartners with the state-required number of DTaP doses, except for Kentucky, which requires ≥5 but reports ≥4 doses of DTaP. §§ Medians calculated from data from 49 states and the District of Columbia (i.e., does not include Wyoming, Houston, New York City, American Samoa, Federated States of Micronesia, Guam, Marshall Islands, Northern Mariana Islands, Palau, Puerto Rico, or U.S. Virgin Islands). Coverage data were reported for 3,988,127 kindergartners. ¶¶ The percentage surveyed likely was <100%, but is reported as 100% based on incomplete information about the actual current enrollment. *** Did not include some types of schools, such as online schools or those located on military bases or in correctional facilities. ††† Kindergarten vaccination coverage data were collected from a sample, and exemption data were collected from a census of kindergartners. §§§ Counted some or all vaccine doses received regardless of Advisory Committee on Immunization Practices recommended age and time interval; vaccination coverage rates reported might be higher than those for valid doses. ¶¶¶ For Palau, estimates represent coverage among children in first grade. **** Reported public school data only. †††† Puerto Rico and U.S. Virgin Islands did not report data for the 2017–18 school year because of widespread logistical issues caused by Hurricane Maria. The median percentage of kindergartners with an exemption from one or more required vaccines (not limited to MMR, DTaP, and varicella vaccines) was 2.2% (range = 0.1% [Mississippi] to 7.6% [Oregon]), compared with 2.0% during the 2016–17 school year (Table 2). The median percentage of medical exemptions was 0.2% (range = <0.1% [Hawaii] to 0.8% [Alaska]); the median percentage of nonmedical exemptions was 2.0% (range = <0.1% [California] to 7.5% [Oregon]). Among the 29 states and DC with an increase in exemptions in 2017–18, vaccination coverage was ≥95% in 15 states for MMR, 16 states for DTaP, and 11 states for 2 doses of varicella. TABLE 2 Estimated number and percentage* of children enrolled in kindergarten with reported type of exemption from vaccination, and grace period/provisional enrollment, by immunization program † — United States and territories, 2017–18 school year Immunization program Medical exemptions, no. (%) Nonmedical exemptions Any exemption Grace period or provisional enrollment§ no. (%) Religious no. Philosophical
no. Total
 no. (%) 2017–18, no. 2017–18
% 2016–17 
% Percentage point difference (2016–17 to 2017–18) Median¶ (0.2) — — (2.0) — 2.2 2.0 0.2 (1.8) Alabama 59 (0.1) 460 —** 460 (0.8) 519 0.9 0.7 0.2 None Alaska 75 (0.8) 549 —** 549 (6.1) 624 7.0 6.8 0.2 NR Arizona 400 (0.5) —†† 4,336 4,336 (5.3) 4,736 5.8 5.1 0.7 NR Arkansas 14 (0.1) 213 428 641 (1.6) 655 1.7 1.4 0.3 3,379 (8.5) California 4,190 (0.7) —§§ —§§ 5 (<0.1) 4,195 0.7 1.1 -0.4 10,568 (1.8) Colorado —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ NR Connecticut 126 (0.3) 764 —** 764 (2.0) 890 2.3 2.1 0.2 None Delaware 3 (0.1) 148 —** 148 (1.3) 151 1.4 1.2 0.2 NR District of Columbia 58 (0.7) 352 —** 352 (4.3) 410 5.0 1.1 3.9 NR Florida 1,051 (0.5) 5,394 —** 5,394 (2.4) 6,445 2.9 2.5 0.4 7,349 (3.3) Georgia 102 (0.1) 3,480 —** 3,480 (2.6) 3,582 2.7 2.8 -0.1 287 (0.2) Hawaii 4 (<0.1) 514 —** 514 (3.1) 518 3.1 2.8 0.3 37 (0.2) Idaho 93 (0.4) —§§ —§§ 1,504 (6.7) 1,597 7.1 6.5 0.6 408 (1.8) Illinois —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ NR Indiana 156 (0.2) 579 —** 579 (0.7) 735 0.9 1.0 -0.1 NR Iowa 93 (0.2) 694 —** 694 (1.8) 787 2.0 1.8 0.2 1,356 (3.4) Kansas 125 (0.3) 544 —** 544 (1.4) 669 1.7 1.8 -0.1 NR Kentucky 174 (0.3) 623 —** 623 (1.1) 797 1.4 1.1 0.3 NR Louisiana 61 (0.1) 49 552 601 (1.0) 662 1.1 0.8 0.3 NA Maine 34 (0.3) 58 608 666 (5.0) 700 5.3 5.0 0.3 186 (1.4) Maryland 390 (0.6) 614 —** 614 (0.9) 1,005 1.5 1.4 0.1 NR Massachusetts 166 (0.3) 687 —** 687 (1.1) 853 1.3 1.3 0.0 None Michigan 251 (0.2) 1,095 3,658 4,753 (4.0) 5,004 4.2 3.7 0.5 719 (0.6) Minnesota —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ NR Mississippi 38 (0.1) —†† ** —**,†† 38 0.1 0.1 0.0 165 (0.4) Missouri —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ —¶¶ NR Montana 48 (0.4) 478 —** 478 (3.9) 526 4.3 3.7 0.6 211 (1.7) Nebraska 192 (0.7) 394 —** 394 (1.5) 586 2.2 2.0 0.2 463 (1.8) Nevada 26 (0.1) 1,170 —** 1,170 (3.1) 1,196 3.2 4.4 -1.2 600 (1.6) New Hampshire 22 (0.2) 334 —** 334 (2.7) 357 2.9 3.2 -0.3 573 (4.7) New Jersey 171 (0.2) 2,148 —** 2,148 (2.0) 2,319 2.2 1.9 0.3 991 (0.9) New Mexico 51 (0.2) 394 —** 394 (1.5) 445 1.7 2.3 -0.6 679 (2.5) New York (incl. New York City) 349 (0.2) 2,199 —** 2,199 (1.0) 2,548 1.1 1.0 0.1 4,170 (1.8) New York City 85 (0.1) 581 —** 581 (0.6) 666 0.7 0.6 0.1 1,173 (1.2) North Carolina 284 (0.2) 2,323 —** 2,323 (1.8) 2,607 2.0 1.8 0.2 2,248 (1.8) North Dakota 31 (0.3) 74 244 318 (3.1) 350 3.4 3.4 0.0 NR Ohio 336 (0.2) —§§ —§§ 3,207 (2.3) 3,543 2.6 2.4 0.2 7,367 (5.3) Oklahoma 91 (0.2) 333 657 991 (1.8) 1,182 2.2 1.9 0.3 NR Oregon 62 (0.1) —§§ —§§ 3,427 (7.5) 3,489 7.6 6.7 0.9 NR Pennsylvania 638 (0.5) 1,600 1,779 3,379 (2.4) 4,017 2.8 2.3 0.5 3,124 (2.2) Rhode Island 10 (0.1) 110 —** 110 (1.0) 120 1.1 1.2 -0.1 NR South Carolina 119 (0.2) 1,028 —** 1,028 (1.8) 1,147 2.0 2.0 0.0 328 (0.6) South Dakota 23 (0.2) 238 —** 238 (2.0) 261 2.2 2.0 0.2 NR Tennessee 114 (0.1) 1,085 —** 1,085 (1.4) 1,199 1.5 1.3 0.2 1,124 (1.4) Texas (incl. Houston) 780 (0.2) —§§ —§§ 7,044 (1.8) 7,825 2.0 1.8 0.2 6,811 (1.8) Houston 66 (0.2) —§§ —§§ 459 (1.1) 525 1.2 1.0 0.2 NR Utah 80 (0.2) 19 2,507 2,526 (5.2) 2,606 5.3 5.1 0.2 1,039 (2.1) Vermont 13 (0.2) 227 —** 227 (3.6) 240 3.8 3.9 -0.1 321 (5.1) Virginia 384 (0.4) 1,125 —** 1,125 (1.1) 1,508 1.5 1.2 0.3 NR Washington 621 (0.7) 202 3,142 3,344 (3.9) 3,966 4.7 4.8 -0.1 1,396 (1.6) West Virginia*** 32 (0.2) —†† —** —**,†† 32 0.2 0.3 -0.1 809 (4.1) Wisconsin 164 (0.2) 291 3,122 3,413 (5.2) 3,577 5.4 5.5 -0.1 1,907 (2.9) Wyoming NA NA NA NA NA NA NA NA NA Territories and associated states American Samoa 0 (0.0) 0 —** 0 (0.0) 0 0 0 0 None Federated States of Micronesia 0 (0.0) 0 0 0 (0.0) 0 0 0 0.0 NR Guam 0 (<0.1) 10 —** 10 (0.4) 10 0.4 0.2 0.2 NR Marshall Islands 0 (0.0) —†† —** 0 (0.0) 0 0 0 0.0 NR Northern Mariana Islands 0 (0.0) 0 0 0 (0.0) 0 0 0 0.0 NR Palau††† 0 (0.0) —§§ —§§ 0 (0.0) 0 0 0 0.0 NR Puerto Rico§§§ NA NA NA NA NA NA NA NA NA U.S. Virgin Islands§§§ NA NA NA NA NA NA NA NA NA Abbreviations: NA = not available (i.e., not collected); None = state does not allow grace period or provisional enrollment; NR = not reported to CDC. * Estimates are adjusted for nonresponse and weighted for sampling where appropriate. † Medical exemptions, nonmedical exemptions, and grace period or provisional enrollment status might not be mutually exclusive. Some children might have both medical and nonmedical exemptions, and some enrolled under a grace period or provisional enrollment might be exempt from one or more vaccinations. § A grace period is a set number of days during which a student can be enrolled and attend school without proof of complete vaccination or exemption. Provisional enrollment allows a student without complete vaccination or exemption to attend school while completing a catch-up vaccination schedule. In states with one or both of these policies, the estimates represent the number of kindergartners within a grace period, provisionally enrolled, or some combination of these categories. ¶ Medians calculated from data from 45 states and District of Columbia; states excluded were Colorado, Illinois, Minnesota, Missouri, and Wyoming. Houston, New York City, American Samoa, Federated States of Micronesia, Guam, Marshall Islands, Northern Mariana Islands, Palau, Puerto Rico, and U.S. Virgin Islands also were excluded. Exemption data were reported for 3,634,631 kindergartners. Grace period or provisional enrollment median was calculated from data from 28 states; data were reported for 2,825,691 kindergartners. ** Philosophical exemptions were not allowed. †† Religious exemptions were not allowed. §§ Religious and philosophical exemptions were not reported separately. ¶¶ Program did not report the number of children with exemptions, but instead reported the number of exemptions for each vaccine, which could count some children more than once. Lower bounds of the percentage of children with any exemptions estimated using the individual vaccines with the highest number of exemptions are for Colorado, 0.2% with medical exemptions, 0.3% with religious exemptions, 4.2% with philosophical exemptions, and 4.7% with any exemptions; for Illinois, 0.2% with medical exemptions, 1.4% with religious exemptions, and 1.6% with any exemptions; for Minnesota, 0.2% with medical exemptions, 3.4% with nonmedical exemptions, and 3.5% with any exemptions; and for Missouri, 0.2% with medical exemptions, 2.1% with religious exemptions, and 2.3% with any exemptions. *** Reported public school data only. ††† For Palau, estimates represent exemptions among children in first grade. §§§ Puerto Rico and U.S. Virgin Islands did not report data for the 2017–18 school year because of widespread logistical issues caused by Hurricane Maria. The median reported percentage of kindergartners attending school during a grace period or provisionally enrolled was 1.8% (range = 0.2% [Georgia and Hawaii] to 8.5% [Arkansas]) (Table 2). In 11 of 28 states reporting for the 2017–18 school year, the percentage of children provisionally enrolled or within a grace period at the time of the assessment exceeded the percentage of children with exemptions from ≥1 vaccines. Among the 26 states and DC with MMR coverage <95%, 20 could potentially achieve ≥95% coverage if all nonexempt students who were provisionally enrolled, in a grace period, or otherwise without evidence of complete vaccination were vaccinated (Figure). FIGURE Estimated percentage of kindergartners with documented up-to-date vaccination for measles, mumps, and rubella vaccine (MMR)*; exempt from one or more vaccines † , § ; and not up to date with MMR and not exempt ¶ — selected states and District of Columbia,** 2017–18 school year * Estimates are based on completed vaccine series and are not MMR-specific for Alabama, Florida, Georgia, Iowa, and New Hampshire. Up-to-date coverage reported here is the lower bound of possible MMR coverage. † Most states report the number of kindergartners with an exemption from one or more vaccines. Estimates reported here might include exemptions from vaccines other than MMR, except in Colorado and Minnesota, where MMR-specific exemptions are reported. § Coverage estimates are based on a sample of kindergartners, and exemption estimates are based on a census for Alaska, Kansas, and Wisconsin. ¶ Includes nonexempt students provisionally enrolled, in a grace period, or otherwise without documentation of complete MMR vaccination. ** Figure includes all states with reported MMR coverage for the 2017–18 school year of <95%, the Healthy People 2020 target for MMR vaccination coverage among kindergartners. https://www.healthypeople.gov/. The figure shows the estimated percentage of kindergartners with documented up-to-date vaccination for measles, mumps, and rubella vaccine (MMR); exempt from one or more vaccines; and not up to date with MMR and not exempt in selected states and District of Columbia during the 2017–18 school year. Discussion During the 2017–18 school year, median kindergarten vaccination coverage was close to 95% for MMR, DTaP, and varicella vaccine. The number of states with coverage ≥95% increased from 20 to 23 (MMR), 23 to 25 (DTaP), and 15 to 17 (2 varicella vaccine doses) since the 2016–17 school year ( 2 , 3 ). Coverage increases in selected states might result from modifications to state programs. For example, Pennsylvania reduced its provisional enrollment period from 240 days to 5 days with a medical certificate indicating the scheduling of missing vaccine doses. The Indiana State Department of Health initiated report cards for schools displaying kindergarten vaccination coverage rates and built a bidirectional interface that increased the amount of data in their immunization information system. Kentucky removed the provider signature requirement when printing a certificate of immunization status, allowing school nurses to use the immunization information system certificate to document vaccination history. In Virginia, the number of local health departments participating in back-to-school immunization clinics for children entering school increased, with most local health departments following up with parents about missing vaccinations before the clinics (J Mellerson, CDC, unpublished data, 2018). Although the overall percentage of children with an exemption was low, this was the third consecutive school year that a slight increase was observed ( 2 ). Reasons for the increase cannot be determined from the data reported to CDC but could include the ease of the procedure for obtaining exemptions ( 4 ) or parental vaccine hesitancy ( 5 ). Reported exemptions do not distinguish between exemptions for one vaccine versus all vaccines. Previous studies indicate that most children with exemptions have received at least some vaccines ( 6 – 8 ). Recent data from the National Immunization Survey indicate the percentage of children reaching age 2 years without having received any vaccinations has increased gradually, from 0.9% for children born in 2011 to 1.3% for children born in 2015 ( 9 ). Two of the 10 states with <90% coverage for ≥1 dose of MMR among children aged 19–35 months in the 2014 National Immunization Survey ( 10 ) (the approximate cohort of children entering kindergarten in the 2017–18 school year) also had <90% coverage for ≥2 doses of MMR among kindergartners in 2017–18; in eight states, coverage with ≥2 doses of MMR was <95%, indicating that some children who were undervaccinated in early childhood do not catch up before kindergarten entry. This highlights the importance of school entry vaccination requirements to ensure catch-up vaccination of unvaccinated and undervaccinated children. In 11 of the 28 states reporting 2017–18 grace period or provisional enrollment data, the percentage of kindergartners in these groups at the time of assessment exceeded the percentage with an exemption from one or more vaccines, representing a group of children who could be fully vaccinated with appropriate follow-up. CDC encourages programs to collect and use these data to identify populations of undervaccinated students. Almost all states could achieve ≥95% vaccination coverage if undervaccinated nonexempt children were vaccinated in accordance with local and state vaccination policies. The findings in this report are subject to at least five limitations. First, comparability is limited because of variation in states’ requirements, data collection methods, and definitions of grace period and provisional enrollment. Second, representativeness might be negatively affected because of data collection methodologies that miss some schools or students or assess vaccination status at different times. Third, actual vaccination coverage, exemption rates, or both might be underestimated or overestimated because of inaccurate or absent documentation. Fourth, median coverage estimates include only 49 of 50 states and DC, median exemption estimates include only 45 states and DC, and the median grace period or provisional enrollment estimate includes only 28 states for the 2017–18 school year. Finally, because most states do not report vaccine-specific exemptions, estimates of potentially achievable MMR coverage are approximations. However, if reported exemptions were for a vaccine or vaccines other than MMR, estimates of potentially achievable MMR coverage would be higher than those presented. Kindergarten vaccination requirements help ensure that students are fully vaccinated with age-appropriate vaccines upon school entry. Although overall vaccination coverage is high, coverage could be improved in many states. CDC works with immunization programs to collect and report data on school vaccination coverage, exemption rates, and grace period and provisional enrollment each year. Immunization programs can use these data to understand and address undervaccination among kindergartners and to identify schools and communities where focused interventions could improve coverage with required vaccines. Summary What is already known about this topic? Immunization programs conduct annual kindergarten vaccination assessments to monitor school-entry vaccination coverage for all state-required vaccines. What is added by this report? Median vaccination coverage was 94.3% for 2 doses of measles, mumps, and rubella vaccine; 95.1% for the state-required number of doses of diphtheria and tetanus toxoids and acellular pertussis vaccine; and 93.8% for 2 doses of varicella vaccine. Although the median exemption rate gradually increased for the third year in a row to 2.2%, most undervaccinated children did not have exemptions. What are the implications for public health practice? School assessment allows immunization programs to target interventions to schools with undervaccinated kindergartners to increase compliance with state and local vaccination requirements.
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              National Update on Measles Cases and Outbreaks — United States, January 1–October 1, 2019

              On October 4, 2019, this report was posted online as an MMWR Early Release. During January 1–October 1, 2019, a total of 1,249 measles cases and 22 measles outbreaks were reported in the United States. This represents the most U.S. cases reported in a single year since 1992 ( 1 ), and the second highest number of reported outbreaks annually since measles was declared eliminated* in the United States in 2000 ( 2 ). Measles is an acute febrile rash illness with an attack rate of approximately 90% in susceptible household contacts ( 3 ). Domestic outbreaks can occur when travelers contract measles outside the United States and subsequently transmit infection to unvaccinated persons they expose in the United States. Among the 1,249 measles cases reported in 2019, 1,163 (93%) were associated with the 22 outbreaks, 1,107 (89%) were in patients who were unvaccinated or had an unknown vaccination status, and 119 (10%) measles patients were hospitalized. Closely related outbreaks in New York City (NYC) and New York State (NYS; excluding NYC), with ongoing transmission for nearly 1 year in large and close-knit Orthodox Jewish communities, accounted for 934 (75%) cases during 2019 and threatened the elimination status of measles in the United States. Robust responses in NYC and NYS were effective in controlling transmission before the 1-year mark; however, continued vigilance for additional cases within these communities is essential to determine whether elimination has been sustained. Collaboration between public health authorities and undervaccinated communities is important for preventing outbreaks and limiting transmission. The combination of maintenance of high national vaccination coverage with measles, mumps, and rubella vaccine (MMR) and rapid implementation of measles control measures remains the cornerstone for preventing widespread measles transmission ( 4 ). Measles cases are classified according to the Council of State and Territorial Epidemiologists’ case definition for measles ( 5 ). Cases are considered internationally imported if at least part of the exposure period (7–21 days before rash onset) occurred outside the United States and rash occurred within 21 days of entry into the United States, with no known exposure to measles in the United States during the exposure period. An outbreak of measles is defined as a chain of transmission of three or more cases linked in time and place as determined by local and state health department investigations. During January 1–October 1, 2019, a total of 1,249 measles cases were reported in 31 states and New York City,† including 1,211 (97%) among U.S. residents. Median patient age was 6 years (interquartile range [IQR] = 2–22 years); 13% were infants aged <12 months (not routinely recommended to receive MMR vaccine), 31% were children aged 1–4 years, 27% were school-aged children aged 5–17 years, and 29% were adults aged ≥18 years (Table). Among all measles patients, 1,107 (89%) were unvaccinated or vaccination status was unknown, and 142 (11%) had received ≥1 MMR vaccination. Most cases (1,054, 84%) were laboratory-confirmed; among 714 (57%) cases for which specimens were available for molecular sequencing, genotypes B3 (49, 7%) and D8 (665, 93%) were identified. Overall, 119 (10%) patients were hospitalized (median age 6 years, IQR = 1–33 years; 20% were infants aged <12 months), 60 (5%) had pneumonia, and one (0.1%) had encephalitis; no deaths were reported to CDC. Eighty-one cases were imported from other countries§ including 52 (64%) cases in U.S. residents returning from travel abroad. Among these 81 internationally imported measles cases, 73 (90%) were in unvaccinated persons or persons for whom vaccination status was unknown. TABLE Number and vaccination status of measles cases, by age group — United States, January 1– October 1, 2019 Age group Measles cases
no. (%) Vaccination status
no. (%)* Unvaccinated Vaccinated Unknown 0–5 mos 43 (3) 43 (100) 0 (0) 0 (0) 6–11 mos 116 (9) 110 (95) 5 (4) 1 (1) 12–15 mos 118 (9) 106 (90) 12 (10) 0 (0) 16 mos–4 yrs 274 (22) 238 (87) 33 (12) 3 (1) 5–17 yrs 339 (27) 295 (87) 26 (8) 18 (5) 18–29 yrs 144 (12) 49 (34) 41 (28) 54 (38) 30–49 yrs 160 (13) 25 (16) 22 (14) 113 (71) ≥50 yrs 55 (4) 6 (11) 3 (5) 46 (84) Overall 1,249 872 (70) 142 (11) 235 (19) * Received ≥1 dose of measles, mumps, and rubella vaccine. In 2019, 22 outbreaks occurred in 17 states (seven were multistate outbreaks); outbreaks accounted for 1,163 (93%) of all reported cases. Eight outbreaks that occurred in underimmunized, close-knit communities accounted for 85% of all cases; outbreaks associated with NYS and NYC accounted for 934 (75%) of all cases. The median outbreak size and duration were six cases (range = 3–646 cases) and 27.5 days (range = 5–230 days), respectively. The median age of patients with outbreak-related cases was 6 years (IQR = 2–19 years). Most outbreak-related cases occurred in persons who were unvaccinated, or in those for whom vaccination status was unknown (1,032, 89%). Most (57, 70%) of the 81 internationally imported cases were not associated with outbreaks. Beginning in late 2018, two closely related outbreaks within Orthodox Jewish communities were reported in NYC and NYS. The first began in NYC with an internationally imported case in a returning U.S. traveler on September 30, 2018; this outbreak lasted 9.5 months and included 702 cases. The second outbreak, which began in NYS with an internationally imported case in a foreign visitor on October 1, 2018, lasted 10.5 months and included 412 cases. The NYC outbreak included 53 cases reported by four other jurisdictions, and the NYS outbreak included four cases reported by two other jurisdictions. Among the 1,487 cases reported to CDC during September 30, 2018–October 1, 2019, 1,397 (94%) cases were associated with 26 outbreaks, and 1,114 (75%) were related to outbreaks in NYC and NYS (Figure). Compared with the NYC and NYS outbreaks, the 24 other U.S. outbreaks reported during the same period were of smaller sizes (median = six cases; range = 3–79 cases), and shorter durations (median = 27 days; range = 5–82 days). Median age was similar between the NYC (median = 4 years; IQR = 1–14 years) and NYS (median = 5 years; IQR = 2–14 years) outbreaks, but lower than that in the other U.S. outbreaks (median = 19 years; IQR = 8–25 years). The proportion of unvaccinated patients and patients with unknown vaccination status was similar in NYC (89%), NYS (91%), and other U.S. (87%) outbreaks. The NYC and NYS outbreaks were associated with multiple internationally imported cases (eight in NYC and 10 in NYS), whereas the other U.S. outbreaks were associated with a median of one internationally imported case. FIGURE Number of reported measles cases (N = 1,487), by week of rash onset — United States, September 30, 2018–October 1, 2019 Abbreviations: NYC = New York City; NYS = New York State. The figure is a histogram, an epidemiologic curve showing the number of reported measles cases (N = 1,487), by week of rash onset in the United States, during September 30, 2018–October 1, 2019. Discussion A total of 1,249 measles cases have been reported in the United States in 2019, with most cases associated with large and closely related outbreaks in New York City and the rest of New York State. Consistent with previous outbreaks that have occurred since measles was declared eliminated in the United States in 2000, most of the other U.S. outbreaks reported in 2019 were of limited size and duration because of high population immunity and rapid implementation of outbreak control measures by local and state public health authorities. In contrast, the two sustained outbreaks in NYC and NYS were larger and lasted longer because of a combination of three important risk factors for measles transmission: 1) pockets of low vaccination coverage and variable vaccine acceptance; 2) relatively high population density and closed social nature of the affected community; and 3) repeated importations of measles cases among unvaccinated persons traveling internationally and returning to or visiting the affected communities. These two almost year-long outbreaks placed the United States at risk for losing measles elimination status. Robust responses in NYC and NYS with multiple partners involved vaccination efforts, including administration of approximately 60,000 MMR vaccine doses in the affected communities; tailored communication campaigns; partnerships with religious leaders, local physicians, health centers, and advocacy groups; and use of local public health statutory authorities. These efforts ended transmission before the 12-month elimination deadline, with the most recent cases reported with rash onset on July 15, 2019, in NYC and August 19, 2019, in the rest of NYS. Both jurisdictions have since passed two incubation periods for measles with no additional reported cases associated with these outbreaks as of October 1, 2019; however, continued vigilance is important to ensure that elimination is sustained. Increased global measles activity and existence of undervaccinated communities place the United States at continual risk for measles cases and outbreaks ( 6 ). Control measures for measles outbreaks have been in place for decades in the United States to limit transmission and prevent reestablishment of endemic transmission ( 7 , 8 ). Core elements include a highly sensitive surveillance system with multiple feedback loops between providers, laboratories, local and state public health authorities, and CDC. These measures are coupled with rapid activation of local and state public health departments in response to every measles case to determine the source of infection, identify susceptible contacts, and implement control measures, including postexposure prophylaxis, exclusion and quarantine, and community-wide vaccination. High national MMR vaccination coverage remains the foundation for preventing more widespread measles transmission ( 9 ). The limited size and duration of 24 of the 26 outbreaks reported during September 2018–September 2019 indicate that high baseline vaccination coverage and standard measles control measures effectively controlled most outbreaks in the United States. Measles outbreaks in undervaccinated, close-knit communities pose challenges that require considerations beyond standard control measures. To identify and protect communities, routine assessments, including school audits and use of electronic immunization information systems to ascertain local vaccination coverage and vaccine access, could help identify critical gaps and resource needs. Because health-seeking behaviors in members of close-knit communities are routinely informed by discussions with like-minded community members, establishing strong community partnerships before outbreaks occur can foster overarching goals to protect the community against public health threats. Public health authorities might also benefit from identifying trusted community liaisons who can assist with case and contact investigations so that standard control measures can be rapidly implemented. Undervaccinated, close-knit communities are not unique to the United States and exist around the world. These communities are at high risk for outbreaks of vaccine-preventable diseases, which threaten the health and safety of vulnerable persons within, as well as outside of, these communities. Therefore, public health authorities need to identify pockets of undervaccinated persons to prevent these outbreaks, which require substantial resources to control. A preventive strategy to build vaccine confidence is important, especially one that uses culturally appropriate communication strategies to offset misinformation and disseminate accurate information about the safety and importance of vaccination in advance of outbreaks. Summary What is already known about this topic? Measles was eliminated in the United States in 2000. High national coverage with measles, mumps, and rubella vaccine and rapid implementation of measles control measures prevent widespread measles transmission. What is added by this report? During January–September 2019, 1,249 U.S. measles cases were reported, the highest annual number since 1992. Eighty-nine percent of measles patients were unvaccinated or had an unknown vaccination status, and 10% were hospitalized. Eighty-six percent of cases were associated with outbreaks in underimmunized, close-knit communities, including two outbreaks in New York Orthodox Jewish communities that threatened measles elimination status in the United States. What are the implications for public health practice? Ensuring high rates of measles immunization in all communities is critical to sustaining measles elimination.
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                Author and article information

                Journal
                MMWR Morb Mortal Wkly Rep
                MMWR Morb. Mortal. Wkly. Rep
                WR
                Morbidity and Mortality Weekly Report
                Centers for Disease Control and Prevention
                0149-2195
                1545-861X
                18 October 2019
                18 October 2019
                : 68
                : 41
                : 905-912
                Affiliations
                Immunization Services Division, National Center for Immunization and Respiratory Diseases, CDC; Association of Schools and Programs of Public Health Fellowship, Washington, DC; Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee; Certified Technical Experts, Inc., Montgomery, Alabama.
                Author notes
                Corresponding author: Ranee Seither, rseither@ 123456cdc.gov , 404-639-8693.
                Article
                mm6841e1
                10.15585/mmwr.mm6841e1
                6802678
                31622283

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