The Roles of Neighborhood Composition and Autism Prevalence on Vaccination Exemption Pockets: A Population-wide Study

The number of children entering schools without mandated vaccinations has increased in high-income countries due to the rise of nonmedical exemptions from school vaccination requirements. Herd immunity is threatened when unvaccinated children are concentrated in spatial pockets. It is often assumed that these exemption clusters are merely the result of population composition. On the other hand, despite the role of vaccine-autism controversy to the current wave of anti-vaccine movement, we do not know if exemption clusters are associated with local autism rates. Our spatial analysis of California shows that while racial/ethnic composition is associated with the locations of large exemption pockets, other sociodemographic factors and access to health care resources have limited geographical span. We decouple the race/ethnicity effect from that of unobserved socioeconomic status by examining families in poverty. Using unique address-level data on the locations of the majority of children with an autism diagnosis, we show that the prevalence of autism is not associated with the locations of large pockets of vaccination exemptions. In addition, we find charter schools in most exemption clusters; potential spillovers from charter schools to neighboring public schools are evaluated. Exemption pockets are not merely the result of population composition and community-level interventions are needed to maintain herd immunity. Highlights Autism prevalence rates are not associated with the locations of large exemption pockets. The average exemption rate in charter schools (7.5%) was higher than private schools. Proportion non-Hispanic white has the strongest association with large exemption clusters. Population composition cannot fully explain the exemption clusters.