Vaccinations, Exemption Rates, Provisional Kindergarten

On October 13, 2017, the CDC published a report that found that, although vaccination rates have remained high and stable, four states have reported coverage of less than 90% for at least one vaccine for at least 6 consecutive years. In addition, coverage can vary within states, and clusters of under-vaccinated kindergartners can exist in states with high overall rates.


The typical age range for kindergartners is four to six years of age. Although vaccination requirements vary by state (the District of Columbia [DC] is counted as a state in this report.), the Advisory Committee on Immunization Practices recommends that children in this age range have received, among other vaccinations, five doses of diphtheria, tetanus, and acellular pertussis vaccine (DTaP); two doses of measles, mumps, and rubella vaccine (MMR); and two doses of varicella vaccine. The report summarizes 2016–17 school year MMR, DTaP, and varicella vaccination coverage reported by immunization programs in 49 states, exemptions in 50 states, and kindergartners provisionally enrolled or within a grace period in 27 states. During the 2016–17 school year, vaccination coverage data were reported for approximately 3,973,172 kindergartners, exemption data for approximately 3,666,870, and grace period and provisional enrollment data for approximately 2,463,131.


Vaccination coverage remains consistently high and exemptions low at state and national levels. Since the 2011–12 school year, median kindergarten MMR vaccination coverage has remained near 95% and median exemption rates have remained at or below two percent. In the 2016–17 school year median vaccination coverage was 94.5 percent for the state-required number of doses of DTaP; 94.0 percent for two doses of MMR; and 93.8 percent for two doses of varicella vaccine. Among the 48 states that required and reported DTaP vaccination, median coverage was 94.5 percent (range = 82.2 percent [DC] to 99.6 percent [Maryland]); 23 states reported coverage at or above 95 percent and six states (Alaska, Arkansas, Colorado, Idaho, Kansas, and DC) reported coverage below 90 percent. Among the 49 states included in this analysis, median MMR coverage was 94 percent (range = 85.6 percent [DC] to 99.4 percent [Mississippi]); 20 states reported coverage at or above 95 percent; and six states (Alaska, Colorado, Idaho, Indiana, Kansas, and DC) reported coverage below 90 percent. Among the 42 states that required and reported two doses of varicella vaccine, median coverage was 93.8 percent (range = 84.6 percent [DC] to 99.4 percent [Mississippi]); 15 states reported coverage at or above 95 percent, and seven states (Alaska, Colorado, Idaho, Indiana, Kansas, Washington, and DC) reported coverage below 90 percent.


Medical exemptions were issued by a health care provider; all other exemptions (i.e., religious and philosophical) were nonmedical. Kindergartners with a history of varicella disease were reported as either vaccinated against varicella or medically exempt, varying by immunization program. The median percentage of kindergartners with an exemption from at least one vaccine was two percent, similar to 2015–16 (1.9 percent). The median percentage of kindergartners with an exemption from one or more required vaccines (not limited to MMR, DTaP, and varicella vaccines) among the 46 states reporting this information was two percent (range = 0.1 percent [Mississippi] to 6.8 percent [Alaska]), similar to the median of 1.9 percent reported for this group during the 2015–16 school year. The percentage of kindergartners with any exemption was less than one percent in four states (Alabama, Louisiana, Mississippi, and West Virginia), and at or above 4 percent in nine states (Alaska, Arizona, Idaho, Maine, Nevada, Oregon, Utah, Washington, and Wisconsin). From the 2015–16 to the 2016–17 school year, the exemption rate decreased by more than one percentage points in two states (California and Vermont) and increased by more than half a percentage point in seven states (Alaska, Georgia, Nevada, New Hampshire, New Mexico, North Carolina, and Wisconsin). Among states that reported exemptions by type, the median percentage of medical exemptions was 0.2 percent (range = <0.1 percent in two states [Delaware and New Mexico] to one and a half percent [Alaska]), and the median percentage of nonmedical exemptions was 1.8 percent (range = 0.5 percent [DC] to 6.5 percent [Oregon]).


Twenty-seven states reported data on kindergartners who, at the time of the assessment, were attending school under a grace period (a set number of days during which a student can be enrolled and attend school without proof of complete vaccination or exemption) or provisional enrollment (a provision that allows a student without complete vaccination or exemption to attend school while completing a catch-up vaccination schedule). Median grace period and provisional enrollment was two percent. The median reported percentage of kindergartners attending school during a grace period or provisional enrollment was two percent (range = 0.2 percent [Georgia] to 8.1 percent [Pennsylvania]). In 12 of 27 states reporting for the 2016–17 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 one or more vaccines.


In 12 of 27 states reporting for the 2016–17 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 for one or more vaccines, indicating that children who do not have exemptions are not receiving their childhood immunizations in a timely fashion. The median percentage of children provisionally enrolled or within a grace period for the 2016–17 school year was two percent, which is the same as for the 2015–16 school year. Pennsylvania’s estimated grace period and provisional enrollment prevalence increased from 5.1 percent to 8.1 percent, probably because the assessment date changed from March 31 in the 2015–16 school year to December 31 in the 2016–17 school year, giving students enrolled under the grace period less time to complete required vaccination and documentation. The CDC encourages programs to collect and use these data to identify areas with high rates of provisional or grace period enrollment, where increasing coverage through a targeted intervention might be possible.


Thirty states published 2015–16 or 2016–17 local-level data (county, parish, school district, school, or other level) online for vaccination coverage, exemptions, or both. Local-level vaccination coverage data provide opportunities for immunization programs to identify schools, districts, counties, or regions susceptible to vaccine-preventable diseases and for schools to address under-vaccination through implementation of existing state and local vaccination policies to protect communities through increased coverage. The number of states sharing local-level school vaccination coverage increased from 25 to 30. The online sharing of local-level data with the public contributes to transparency in public health by placing information about the risk for vaccine preventable diseases in the hands of parents and communities. The type of data published (exemptions, vaccine-specific coverage, complete vaccination, compliance with documentation requirements, and other information) varies across states, as does the geographic level of detail (school, school district, county, region of the state, or other geographic or administrative area), and the method of displaying the data (table, chart, map, or other format).


Four states (California, New York, North Dakota, and Tennessee) reported increases in coverage of at or above one and a half percentage points for all reported vaccines. These increases might have resulted from programmatic measures to address under-vaccination and incomplete documentation of vaccination during the 2016–17 school year. California eliminated new nonmedical exemptions for kindergartners attending public or private school and continued to educate school staff members on criteria for provisional enrollment, thus reducing provisional enrollment from 4.4 percent to 1.9 percent. New York conducted webinars to train school staff members on vaccination requirements, exemptions, and exclusion policies; coverage increased by more than one and a hal percentage points for all reported vaccines in 2016–17. In North Dakota, school superintendents were educated about the importance of immunizations and their mandated role in enforcement of requirements, which prompted most school districts in the state to begin strict enforcement of school vaccination requirements, leading to increases in coverage of more than three percentage points for MMR, DTaP, and varicella vaccine in 2016–17. In Tennessee, the immunization program worked to increase the proportion of public school kindergartners who were completely up to date in the state’s immunization information systems and to improve schools’ capacity to correctly assess student vaccination status. MMR, DTaP, and varicella vaccination coverage increased more than percentage points in Tennessee in 2016–17.


The findings in this report are subject to at least four limitations, which have been reported previously. First, comparability is limited because of variations 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. Collecting vaccination and exemption data from a validated census of schools and students can improve comparability and representativeness of the data, and therefore, census data are the most programmatically useful. The majority of immunization programs do use a census to collect vaccination and exemption data. Third, actual vaccination coverage, exemption estimates, or both might be under- or overestimated because of improper or absent documentation. Finally, median coverage estimates include only 48 of 50 states and DC, median exemptions estimates include only 45 of 50 states and DC, and the median grace period or provisional enrollment estimate includes only 27 states for the 2016–17 school year.


State and local school vaccination requirements help protect students and communities against vaccine-preventable diseases. Kindergarten vaccination requirements provide an opportunity for children to be fully vaccinated with recommended age-appropriate vaccines and to catch up on any missed early childhood vaccinations. The CDC works with immunization programs to monitor kindergarten vaccination coverage, improve data quality, and promote data use for effective program planning. Based on state-level kindergarten vaccination data reported to the CDC, median vaccination coverage was consistently high and median exemption rates were consistently low. However, clusters of low vaccination coverage continue to serve as opportunities for outbreaks of vaccine-preventable diseases. Because vaccination coverage and exemption levels are clustered locally, availability of local-level vaccination data can help immunization programs identify schools that might be vulnerable in an outbreak. The CDC is working with programs to improve collection and use of grace period and provisional enrollment data to understand contributing factors for reported under-vaccination and identify programmatic actions that might increase vaccination coverage among kindergartners.


See the CDC Report


See also Medical Law Perspectives Report: Vaccines: An Ounce of Prevention May Lead to a Pound of Injury


See the Medical Law Perspectives Blog: Vaccination Decisions Have Legal Repercussions, Not Just Medical Ones