Impact of Addition of Philosophical Exemptions on Childhood Immunization Rates

Background: Although incidence of vaccine-preventable diseases has decreased, states' school immunization requirements are increasingly challenged. Subsequent to a federal court ruling affecting religious immunization exemptions to school requirements, new legislation made philosophical immunization exemptions available in Arkansas in 2003-2004. This retrospective study conducted in 2006 describes the impact of philosophical exemption legislation in Arkansas. Methods: Arkansas Division of Health data on immunization exemptions granted were linked to Department of Education data for all school attendees (grades K through 12) during 2 school years before the legislation (2001-2002 and 2002-2003 [Years 1 and 2, respectively]) and 2 years after philosophical exemptions were available (2003-2004 and 2004-2005 [Years 3 and 4, respectively]). Changes in numbers, types, and geographic distribution of exemptions granted are described. Results: The total number of exemptions granted increased by 23% (529 to 651) from Year 1 to 2; by 17% (total 764) from Year 2 to 3 after philosophical exemptions were allowed; and by another 50% from Year 3 to 4 (total 1145). Nonmedical exemptions accounted for 79% of exemptions granted in Years 1 and 2, 92% in Year 3, and 95% in Year 4. Importantly, nonmedical exemptions clustered geographically, suggesting concentrated risks for vaccine-preventable diseases in Arkansas communities. Conclusions: Legislation allowing philosophical exemptions from school immunization requirements was linked to increased numbers of parents claiming nonmedical exemptions, potentially causing an increase in risk for vaccine-preventable diseases. Continued education and dialogue are needed to explore the balance between individual rights and the public's health.