title: Impact of Nonmedical Vaccine Exemption Policies on the Health and Economic Burden of Measles.
abstract: Despite relatively high national vaccination coverage for measles, geographic vaccination variation exists resulting in clusters of susceptibility. A portion of this geographic variation can be explained by differences in state policies related to nonmedical vaccine exemptions. The objective of this analysis was to determine the magnitude, likelihood, and cost of a measles outbreak under different nonmedical vaccine exemption policies.
  
  
  
  An agent-based transmission model simulated the likelihood and magnitude of a measles outbreak under different nonmedical vaccine exemption policies, previously categorized as easy, medium, or difficult. The model accounted for measles herd immunity, infectiousness of the pathogen, vaccine efficacy, duration of incubation and communicable periods, acquired natural immunity, and the rate of recovery. Public health contact tracing was also modeled. Model outcomes, including the number of secondary cases, hospitalizations, and deaths, were monetized to determine the economic burden of the simulated outbreaks.
  
  
  
  A state with easy nonmedical vaccine exemption policies is 140% and 190% more likely to experience a measles outbreak compared with states with medium or difficult policies, respectively. The magnitude of these outbreaks can be reduced by half by strengthening exemption policies. These declines are associated with significant cost reductions to public health, the health care system, and the individual.
  
  
  
  Strengthening nonmedical vaccine exemption policies is 1 mechanism to increase vaccination coverage to reduce the health and economic effect of a measles outbreak. States exploring options for decreasing their vulnerability to outbreaks of vaccine-preventable diseases should consider more stringent requirements for nonmedical vaccine exemptions.
authors.affiliation: Department of Clinical Pharmacy, University of Colorado Anschutz Medical Campus, Aurora. Electronic address: Melanie.Whittington@ucdenver.edu.
authors.forename: Melanie D
authors.initials: MD
authors.lastname: Whittington
authors.affiliation: Adult and Child Consortium for Health Outcomes Research and Delivery Science, University of Colorado Anschutz Medical Campus, Aurora; Children's Hospital Colorado, Aurora.
authors.forename: Allison
authors.initials: A
authors.lastname: Kempe
authors.affiliation: Adult and Child Consortium for Health Outcomes Research and Delivery Science, University of Colorado Anschutz Medical Campus, Aurora; Department of Pediatrics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora.
authors.forename: Amanda
authors.initials: A
authors.lastname: Dempsey
authors.affiliation: Disease Control and Environmental Epidemiology Division, Colorado Department of Public Health and the Environment, Denver.
authors.forename: Rachel
authors.initials: R
authors.lastname: Herlihy
authors.affiliation: Department of Clinical Pharmacy, University of Colorado Anschutz Medical Campus, Aurora.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Campbell
mesh_terms: D017281:Cost of Illness; D006291:Health Policy; D006801:Humans; D008457:Measles / Q000453:epidemiology* / Q000517:prevention & control*; D014611:Vaccination / Q000331:legislation & jurisprudence*
keywords: agent-based transmission model; measles; vaccination; vaccine exemptions