Vaccination Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten – United States, 2020-21 School Year

Vaccination Coverage with Selected Vaccines and Exemption Rates Among Children in Kindergarten – United States, 2020-21 School Year

State and local school vaccination requirements serve to protect students against vaccine-preventable diseases (1). 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 (2). 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).

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Discussion

During the 2020–21 school year, vaccination coverage among kindergartners nationwide was lower than during the 2019–20 school year at approximately 94% (2,3) for MMR, DTaP, and varicella vaccines, a level just under the target of 95%; coverage for all three vaccines decreased in a majority of states. National MMR coverage among kindergartners fell below the Healthy People 2030 target of 95% (4). Reported enrollment and response rates also decreased nationally and in a majority of states (3). Some of the decreases in enrollment could be because of schools not reporting these data to state immunization programs, or parents might have decided to have the child delay or skip the kindergarten year. The kindergarten assessment for the 2021–22 school year will include these students if they are enrolled in kindergarten for the 2021–22 school year, but not if they were enrolled in first grade for the 2021–22 school year.

The overall percentage of children with an exemption remained low during the 2020–21 school year at 2.2%; the percentage of children with exemptions decreased in 37 states. Nonexempt undervaccinated students often attend school while in a grace period or are provisionally enrolled; in many states, these policies were expanded either formally or informally during the 2020–21 school year. States described reluctance to schedule and reduced access to well-child appointments, expanded grace period or provisional enrollment, and easing of vaccination requirements for remote learners, reduced submission of documentation by parents, less time for school nurses to follow-up with students missing documentation or vaccines, fewer staff members to conduct kindergarten vaccination coverage assessment and reporting activities, lower response rates from schools, and both extended and compressed kindergarten vaccination coverage data collection schedules, all related to COVID-19 (CDC, School Vaccination Coverage Report, unpublished data, 2021). During the 2020–21 school year, 10% of school principals reported that fewer students were fully vaccinated in that school year.§§§ Twenty-seven percent of school nurses reported that fewer students were fully vaccinated in the 2020–21 school year, and 46% of school nurses reported that school vaccination requirements were a somewhat lower or much lower priority compared with previous years (CDC, Impact of the COVID-19 Pandemic on K–12 School Nurses 2020/2021 School Year, unpublished data, 2021). Decreases in vaccine ordering and administration during 2020 also support the measured decreases in coverage (58).

The findings in this report are subject to at least five limitations. First, comparison between states is limited because of variation in states’ requirements such as vaccine required, number of doses required, date required, and type of documentation accepted; data collection methods; exemptions allowed; and definitions of grace period and provisional enrollment. Second, representativeness might be negatively affected because of data collection methods that assess vaccination status at different times or miss some schools or students, such as students who were homeschooled. Third, vaccination coverage, exemption rates, or both might be underestimated or overestimated because of inaccurate or absent documentation or missing schools. Fourth, national coverage estimates for the 2020–21 school year include only 47 of 50 states and DC but use lower-bound estimates for nine states; exemption estimates include 48 states and DC but use lower-bound estimates for four states, and grace period or provisional enrollment estimates include only 28 states. Finally, the COVID-19 pandemic response created various barriers that limited the amount and quality of student vaccination data collected and reported by local health departments. These barriers included schools closing or shifting to virtual learning, many states effectively easing vaccination requirements, and the reassigning of state and local health departments’ staff members to response activities.

Among children aged 4–6 years, vaccination coverage is higher among those in kindergarten than among those not yet in kindergarten (9). Although coverage among kindergartners was lower in the 2020–21 school year than in 2019–20 for all reported vaccines, vaccination coverage might be lower among kindergarten-age children whose school entry has been delayed. Vaccination coverage could be improved by increased outreach by schools and immunization programs to first-time students, including kindergartners and first graders, and by follow-up with undervaccinated students. As schools return to in-person learning, high vaccination coverage is necessary to continue protecting students from vaccine-preventable diseases.

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