Vaccine exemptions and the kindergarten vaccination coverage gap

Background: Vaccination requirements for kindergarten entry vary by state, but all states require 2 doses of measles containing vaccine (MCV) at kindergarten entry.

Objective: To assess (i) national MCV vaccination coverage for children who had attended kindergarten; (ii) the extent to which undervaccination after kindergarten entry is attributable to parents' requests for an exemption; (iii) the extent to which undervaccinated children had missed opportunities to be administered missing vaccine doses among children whose parent did not request an exemption; and (iv) the vaccination coverage gap between the "highest achievable" MCV coverage and actual MCV coverage among children who had attended kindergarten.

Methods: A national survey of 1465 parents of 5-7year-old children was conducted during October 2013 through March 2014. Vaccination coverage estimates are based provider-reported vaccination histories. Children have a "missed opportunity" for MCV if they were not up-to-date and if there were dates on which other vaccines were administered but not MCV. The "highest achievable" MCV vaccination coverage rate is 100% minus the sum of the percentages of (i) undervaccinated children with parents who requested an exemption; and (ii) undervaccinated children with parents who did not request an exemption and whose vaccination statuses were assessed during a kindergarten grace period or period when they were provisionally enrolled in kindergarten.

Results: Among all children undervaccinated for MCV, 2.7% were attributable to having a parent who requested an exemption. Among children who were undervaccinated for MCV and whose parent did not request an exemption, 41.6% had a missed opportunity for MCV. The highest achievable MCV coverage was 98.6%, actual MCV coverage was 90.9%, and the kindergarten vaccination gap was 7.7%.

Conclusion: Vaccination coverage may be increased by schools fully implementing state kindergarten vaccination laws, and by providers assessing children's vaccination status at every clinic visit, and administering missed vaccine doses.