Abstract and Introduction
State and local school vaccination requirements serve to protect students against vaccine-preventable diseases. This report summarizes data collected for the 2020–21 school year by state and local immunization programs* on vaccination coverage among children in kindergarten in 47 states and the District of Columbia (DC), exemptions for kindergartners in 48 states and DC, and provisional enrollment or grace period status for kindergartners in 28 states. Vaccination coverage† nationally was 93.9% for 2 doses of measles, mumps, and rubella vaccine (MMR); 93.6% for the state-required number of doses of diphtheria, tetanus, and acellular pertussis vaccine (DTaP); and 93.6% for the state-required doses of varicella vaccine. Compared with the 2019–20 school year, vaccination coverage decreased by approximately one percentage point for all vaccines. Although 2.2% of kindergartners had an exemption from at least one vaccine,§ an additional 3.9% who did not have a vaccine exemption were not up to date for MMR. The COVID-19 pandemic affected schools' vaccination requirement and provisional enrollment policies, documentation, and assessment activities. As schools continue to return to in-person learning, enforcement of vaccination policies and follow-up with undervaccinated students are important to improve vaccination coverage.
To meet state and local school entry requirements, parents submit 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 gives authorized personnel secure access to public health applications operated by CDC. CDC uses these counts to produce state-level and national-level estimates of vaccination coverage. During the 2020–21 school year, 47 states and DC reported coverage for all state-required vaccines among public and private school kindergartners;¶ 48 states and DC reported exemption data on public school kindergartners and 47 states and DC 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. Hepatitis B and poliovirus vaccination coverage, not included in this report, are available at SchoolVaxView. Twenty-eight 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). Thirty states and DC reported the number of kindergartners who had no documentation of any vaccinations or exemptions. Seventeen states reported the number of kindergartners who were out of compliance; these kindergartners did not have complete documentation of having received all required vaccinations but were not eligible for provisional enrollment and did not have documented exemptions for the missing vaccinations. This measure includes those with no documentation at all. All counts were current as of the time of the assessment.** National estimates, medians, and summary measures include only U.S. states and DC. This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy.††
Vaccination coverage and exemption estimates were adjusted according to survey type and response rate.§§ National estimates measure coverage and exemptions among all kindergartners, whereas medians measure the midpoint of state-level coverage regardless of population size. During the 2020–21 school year, 3,520,205 children in 48 states and DC were reported by immunization programs as enrolled in kindergarten.¶¶ Reported estimates are based on 3,187,569 of these kindergartners who were surveyed for vaccination coverage; 3,337,916 for exemptions; 2,467,326 for grace period and provisional enrollment; 1,799,190 for documentation; and 1,049,075 for compliance. Kindergarten enrollment reported by the 48 states and DC was approximately 10% lower than that reported for the 2019–20 school year by 48 states. Potentially achievable coverage with MMR, defined as the sum of the percentage of children who were up to date with 2 doses of MMR and those with no documented vaccination exemption but not up to date, 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.
Vaccination assessments varied by state because of differences in required vaccines and doses, vaccines assessed, methods of data collection, and data reported (Supplementary Table 1, https://stacks.cdc.gov/view/cdc/116354). Kindergartners were considered up to date for a given vaccine if they received all doses of that vaccine required for school entry,*** except in nine states††† that reported kindergartners as up to date for any given vaccine only if they 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.
Nationally, 2-dose MMR coverage was 93.9% (median = 93.7%; range = 78.9% [DC] to ≥98.9% [Mississippi]). Coverage ≥95% was reported by 16 states and <90% by 7 states and DC (Table). DTaP coverage was 93.6% (range = 78.5% [DC] to ≥98.9% [Mississippi]). Coverage ≥95% was reported by 16 states, and coverage <90% by eight states and DC. Varicella vaccine coverage nationally was 93.6% (range = 78.0% [DC] to ≥98.9% [Mississippi]), with 17 states reporting coverage ≥95% and nine states and DC reporting <90% coverage.
The percentage of kindergartners with an exemption for ≥1 required vaccines (not limited to MMR, DTaP, and varicella vaccines) was 2.2% in 2020–21 (range = 0.1% [Mississippi and New York] to 8.2% [Idaho]), similar to the 2.5% reported during the 2019–20 school year (Table). Nationally, 0.2% of kindergartners had a medical exemption and 1.9% had a nonmedical exemption (Supplementary Table 2, https://stacks.cdc.gov/view/cdc/116355). The percentage of kindergartners provisionally enrolled in kindergarten or within a grace period among the 28 states reporting these data was 2.0% (range = 0.1% [Hawaii] to 10.0% [Arkansas]) (Table).
Among states that reported data for both 2019–20 and 2020–21, MMR coverage and exemptions for ≥1 vaccines decreased in approximately 75% of states; grace period or provisional enrollment increased in 18 of the 28 states reporting this measure (Figure 1). The proportion of students who were not fully vaccinated and not exempt increased in a majority of states. Among states reporting these measures in 2020–21, the proportion of kindergartners attending school with no documentation of required vaccinations or exemptions ranged from 0.1% (Pennsylvania and Virginia) to 8.3% (Maryland); the proportion out of compliance with school requirements ranged from 0.2% (Florida) to 16.6% (Indiana) (Table). Among the 33 states and DC with MMR coverage <95%, all but two could potentially achieve ≥95% MMR coverage if all nonexempt kindergartners who were within a grace period, provisionally enrolled, or out of compliance received vaccination (Figure 2).
Change in measles, mumps, and rubella vaccine coverage, any exemption, grace period or provisional enrollment, and no documentation among kindergartners* — 47 states,† 2019–20 to 2020–21 school year
Abbreviation: MMR = measles, mumps, and rubella vaccine.
*States are sorted from lowest to highest by change in MMR coverage (n = 46), any exemption (n = 47), grace period or provisional enrollment (n = 28), and no documentation (n = 29). Not all states reported data for all categories.
†Delaware and District of Columbia did not report for any categories for the 2019–20 school year, and Illinois and West Virginia did not report for any categories for the 2020–21 school year. All were excluded from this analysis.
Potentially achievable coverage*,† with measles, mumps, and rubella vaccine among kindergartners, by state — 47§ states and District of Columbia, 2020–21 school year
Abbreviation: MMR = measles, mumps, and rubella vaccine.
*States are ranked from lowest to highest by potentially achievable coverage. Potentially achievable coverage was 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 documented vaccine exemption.
†The exemptions used to calculate the potential increase in MMR coverage for Arizona, Arkansas, Colorado, District of Columbia, Idaho, Maine, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, Nevada, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Rhode Island, Texas, Utah, Vermont, and Wisconsin were the number of children with exemptions specifically for MMR vaccine. For all other states, numbers were based on an exemption to any vaccine.
§Alaska, Illinois, and West Virginia did not report kindergarten vaccination coverage for the 2020–21 school year and are excluded from this analysis.
Morbidity and Mortality Weekly Report. 2022;71(16):561-568. © 2022 Centers for Disease Control and Prevention (CDC)