Vaccine policy and Arkansas childhood immunization exemptions: a multi-year review.

BACKGROUND An increase in total vaccine exemptions (medical, philosophic, and religious) occurred in Arkansas after a 2003 legislation added a philosophic category and used a new process for vaccine exemptions. By legislative requirement, the Arkansas Department of Health monitored exemptions through the 2009-2010 school year. PURPOSE The goal of the study was to determine the prevalence of vaccine exemption in 2003-2010 compared to the number of requests prior to the legislation enacted in 2003. METHODS Exemptions were calculated by school-age category using raw numbers of exemptions, total estimates of the population by age level, enrollment numbers for students in public and private schools, and in enrolled college students born after 1957. Exemptions also were analyzed by school district, grade level, type of exemption, and particular vaccine exemption requested. RESULTS Overall exemptions continued to rise each year, with an average increase of 23.1% annually. Medical exemptions declined from an average of 21.3% of all exemptions before to an average of 4.8% thereafter. The greatest increase in number of exemptions was observed among college students. The highest total rate of exemptions per precollegiate student population was <1.3%. When exemption requests were categorized, most (79%) were for exemptions from "all vaccines." The most common single exempted vaccine was MMR (measles, mumps, rubella). CONCLUSIONS Since philosophic exemptions were codified in 2003 in Arkansas, the number and rate of vaccine exemptions continue to progressively increase. However, vaccine-preventable disease clusters have not yet been linked to or identified in any population with a high rate of vaccine exemptions.