Exempting schoolchildren from immunizations: states with few barriers had highest rates of nonmedical exemptions.

Rates of nonmedical exemptions from school immunizations are increasing and have been associated with resurfacing clusters of vaccine-preventable diseases, such as measles. Historically, state-level school immunization policies successfully suppressed such diseases. We examined state immunization exemption regulations across the United States. We assessed procedures for exempting schoolchildren and whether exemption rates were associated with the complexity of the procedures. We also analyzed legal definitions of religious objections and state legislatures' recent modifications to exemption policies. We found that states with simpler immunization exemption procedures had nonmedical exemption rates that were more than twice as high as those in states with more-complex procedures. We also found that the stringency of legal definitions of religious exemptions was not associated with exemption procedure complexity. Finally, we found that although there were more attempts by state legislatures to broaden exemptions than to tighten them in 2011-13, only bills tightening exemptions passed. Policy makers seeking to control exemption rates to achieve public health goals should consider tightening nonmedical exemption procedures and should add vaccine education components to the procedures by either mandating or encouraging yearly educational sessions in schools for parents reluctant to have their children vaccinated.