Implications of philosophical and personal belief exemptions on re-emergence of vaccine-preventable disease: the role of spatial clustering in under-vaccination.

Vaccine exemption policies vary by state, and it has been demonstrated that easier protocols for personal/philosophical belief exemptions are associated with lower vaccine coverage at the state level. However, this does not lead to ubiquitously lower immunization rates across the state, as shown by variability in county-level exemption rates. Rather, there is geographical clustering of areas which are then more vulnerable to outbreaks of vaccine-preventable diseases. Understanding both state and local patterns of vaccine exemptions and developing policies and public health interventions to increase coverage in high-risk areas is critical. At all levels of healthcare, efforts must be made to encourage vaccination education and legislation to protect the public's health.