Abstract and Introduction
State and local school vaccination requirements protect students and communities against vaccine-preventable diseases. This report summarizes data collected by state and local immunization programs* on vaccination coverage and exemptions to vaccination among children in kindergarten in 49 states† and the District of Columbia and provisional enrollment or grace period status for kindergartners in 27 states§ for the 2021–22 school year. Nationwide, vaccination coverage with 2 doses of measles, mumps and rubella vaccine (MMR) was 93.5%¶; with the state-required number of diphtheria, tetanus, and acellular pertussis vaccine (DTaP) doses was 93.1%**; with poliovirus vaccine (polio) was 93.5%††; and with the state-required number of varicella vaccine doses was 92.8%.§§ Compared with the 2020–21 school year, vaccination coverage decreased 0.4–0.9 percentage points for all vaccines. Although 2.6% of kindergartners had an exemption for at least one vaccine,¶¶ an additional 3.9% who did not have an exemption were not up to date with MMR. Although there has been a nearly complete return to in-person learning after COVID-19 pandemic-associated disruptions, immunization programs continued to report COVID-19–related impacts on vaccination assessment and coverage. Follow-up with undervaccinated students and catch-up campaigns remain important for increasing vaccination coverage to prepandemic levels to protect children and communities from vaccine-preventable diseases.
As mandated by state and local school entry requirements, parents provide children's vaccination or exemption documentation to schools, or schools obtain records from state immunization information systems. Federally funded immunization programs work with departments of education, school nurses, and other school personnel to assess vaccination 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, a federal, web-based system that provides authorized personnel with secure access to public health applications operated by CDC. CDC uses these counts to produce state- and national-level estimates of vaccination coverage among children in kindergarten. During the 2021–22 school year, 49 states and the District of Columbia reported coverage with all state-required vaccines and exemption data for public school kindergartners; 48 states and the District of Columbia reported coverage with all state-required vaccines and exemption data for private school kindergartners.*** Data from cities were included with their state data. State-level coverage and national and median coverage with the state-required number of DTaP, MMR, polio, and varicella vaccine doses are reported. Hepatitis B vaccination coverage is not included in this report but is available at SchoolVaxView. Twenty-seven states reported the number of kindergartners who were attending 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). All counts were current as of the time of the assessment.††† National estimates, medians, and summary measures include only U.S. states and the District of Columbia.
Vaccination coverage and exemption estimates were adjusted on the basis of survey type and response rate.§§§ National estimates measure coverage and exemptions among all kindergartners, whereas medians indicate the midpoint of state-level coverage, irrespective of population size. During the 2021–22 school year, immunization programs reported 3,837,259 children enrolled in kindergarten in 49 states and the District of Columbia.¶¶¶ Reported estimates are based on 3,543,080 (92.2%) children who were surveyed for vaccination coverage, 3,688,904 (96%) surveyed for exemptions, and 2,487,284 (65%) surveyed for grace period and provisional enrollment status. Potentially achievable coverage with MMR (the sum of the percentage of children who were up to date with 2 doses of MMR and those not up to date but with no documented vaccination exemption) was calculated for each state. Nonexempt students include those who were provisionally enrolled in kindergarten, in a grace period, or otherwise without documentation of complete vaccination. SAS software (version 9.4; SAS Institute) was used for all analyses. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.****
Vaccination assessments varied by state because of differences in required vaccines and required numbers of doses, vaccines assessed, methods of data collection, and data reported (Supplementary Table 1, https://stacks.cdc.gov/view/cdc/123203). Kindergartners were considered up to date with a given vaccine if they received all doses required for school entry, except in eight states†††† that reported kindergartners as up to date for any vaccine only if they had received all doses of all vaccines required for school entry. States were asked to report any COVID-19–related impact on kindergarten vaccination measurement and coverage through a combination of structured responses and open-ended questions.
Nationally, 2-dose MMR coverage was 93.5% (range = 78.0% [Alaska] to 98.0% [New York]), with coverage of ≥95% reported by 13 states and <90% by nine states and the District of Columbia (Table). DTaP coverage was 93.1% (range = 78.0% [Alaska] to 98.3% [Virginia]); coverage of ≥95% was reported by 14 states and of <90% by 12 states and the District of Columbia. Polio vaccination coverage was 93.5% (range = 77.1% [Alaska] to 97.6% [Louisiana and Nebraska]), with coverage of ≥95% reported by 13 states and <90% by 10 states and the District of Columbia. Varicella vaccination coverage nationally was 92.8% (range = 76.1% [Alaska] to 98.0% [West Virginia]), with 12 states reporting coverage ≥95% and nine states and the District of Columbia reporting <90% coverage. Coverage decreased in most states for all vaccines compared with the 2020–21 school year (Supplementary Figure, https://stacks.cdc.gov/view/cdc/123205).
Overall, 2.6% of kindergartners had an exemption (0.2% medical and 2.3% nonmedical§§§§) for one or more required vaccines (not limited to MMR, DTaP, polio, and varicella vaccines) in 2021–22 (range = 0.1% [Mississippi, New York, and West Virginia] to 9.8% [Idaho]), compared with 2.2% reported during the 2020–21 school year (Supplementary Table 2, https://stacks.cdc.gov/view/cdc/123204). Among 27 states reporting data on provisional kindergarten enrollment or grace period attendance, 2.4% of children were so enrolled (range = <0.1% [Hawaii] to 8.5% [Wisconsin]).
Nationally, MMR coverage for both the 2020–21 and 2021–22 school years was lower than that reported since 2013–14 (Figure 1). Nationwide, 3.9% of kindergarten students were not fully vaccinated and not exempt. Among the 36 states and the District of Columbia with MMR coverage <95%, all but four could potentially achieve ≥95% MMR coverage if all nonexempt kindergartners who were within a grace period, provisionally enrolled, or otherwise enrolled in school without documentation of vaccination were vaccinated (Figure 2).
Estimated national coverage with 2 doses of measles, mumps, and rubella vaccine among kindergartners — United States, 2013–14 to 2021–22 school years
Abbreviation: MMR = measles, mumps, and rubella vaccine.
Potentially achievable coverage*,† with measles, mumps, and rubella vaccine among kindergartners, by state — United States, 2021–22 school year
Abbreviations: MMR = measles, mumps, and rubella vaccine; UTD = up to date.
*States are ranked from lowest to highest potentially achievable coverage. Potentially achievable coverage is estimated as the sum of the percentage of students with UTD MMR and the percentage of students without UTD MMR and without a documented vaccine exemption.
†The exemptions used to calculate the potential increase in MMR coverage for Alaska, Arizona, Arkansas, Colorado, Delaware, District of Columbia, Idaho, Illinois, Maine, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, Nevada, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, South Carolina, Texas, Utah, Vermont, Washington, Wisconsin, and Wyoming are the number of children with exemptions specifically for MMR. For all other states, numbers are based on an exemption to any vaccine.
Twenty-three states reported COVID-19–related impacts on data collection including lower response rates from schools, data collection extensions and delays, and incomplete data from schools that did respond; 30 states reported lingering COVID-19–related impacts on vaccination coverage, mostly related to reduced access to vaccination appointments and local or school level extensions of grace period or provisional enrollment policies (CDC, School Vaccination Coverage Report, unpublished data, 2022).
Morbidity and Mortality Weekly Report. 2023;72(2)::26-32. © 2023 Centers for Disease Control and Prevention (CDC)