BACKGROUND: According to the 2014 MMWR report, Vaccination Coverage among Children in Kindergarten -United States, Utah had a measles, mumps, and rubella (MMR) coverage rate of 98.5% despite having an exemption rate of 4.4%. To better understand this discrepancy, the Utah Department of Health (UDOH) conducted an evaluation of the processes and accuracy of Utah’s data as published in this report.
METHODS: Utah’s data originates from a census of schools representing 100% of students’ vaccine status upon kindergarten enrollment. Students are classified as: adequately immunized, non-compliant, exempt, or conditionally enrolled. School data is reported to UDOH which then calculates vaccine exemption and coverage rates and submits aggregate data to the Centers for Disease Control and Prevention (CDC) for publication. Schools’ exemption data were validated by collecting personal exemption forms for kindergartners in the 2013-2014 school year from local health departments (LHDs) and schools. Exemption forms were cross-referenced by matching name and birth date with Utah’s Immunization information system (USIIS) to obtain vaccine histories. Data were analyzed to determine if kindergarten students received a vaccine despite claiming a personal exemption. To evaluate the accuracy of data supplied to the CDC, investigators recalculated the MMR coverage rate by using a formula established by Utah’s Immunization Program.
RESULTS: Utah schools reported 2,406 kindergarten personal exemptions for the 2013-2014 school year. Investigators were able to collect 1,792 exemption forms. 63% (n=1,132) of kindergartners who claimed an exemption reported a vaccine on their USIIS record. 23% (n=416) of students who were granted an exemption received a vaccine they opted out of on or after the exemption form date. Furthermore, a calculation error was found with the formula UDOH used for the 2014 MMWR report. After validating students’ exemption status and updating coverage levels, the estimated MMR coverage rate decreased to 95.4% and the estimated exemption rate decreased to 3.6%. Investigators observed that there are not standardized collection or storage procedures in place for LHDs regarding exemptions. It was also observed that there may be confusion about a student’s vaccine status at the time of enrollment, which can artificially inflate Utah’s exemption rate.
CONCLUSIONS: Utah’s vaccine coverage and exemption rates are reliant on accurate school data and calculations of coverage rates. Conducting an annual vaccine exemption validation study may increase the accuracy of Utah’s exemption rate. Findings from this evaluation will help investigators educate schools, providers, and LHDs on appropriate collection, storage, and reporting of exemptions granted to students.