The Correlation of Nonmedical Vaccine Exemptions and Clusters of Pertussis Cases in the United States, 2012

Abstract

The aim of this investigation was to determine if there was a correlation between nonmedical vaccine exemptions and clusters of pertussis cases in the United States during 2012. It was hypothesized that counties that have high rates of nonmedical vaccine exemptions will also have high rates of reported pertussis cases. Kindergarten immunization data as well as pertussis cases at the county level were examined. This study used incidence rates, linear regression models, and a statistical analysis program called SaTScan version 9.4 to determine if there was a correlation between geographical clusters of nonmedical vaccine exemptions and geographic clusters of pertussis cases in the United States during 2012. The results of the investigation indicated that there is a moderate correlation between nonmedical vaccine exemptions and pertussis cases at the county level. It was concluded that geographic clusters of nonmedical vaccine exemptions do pose a risk to the surrounding communities. The results suggest that states should actively monitor trends in nonmedical vaccine exemptions at the county level to better understand the impact of nonmedical vaccine exemptions on public health. In addition, states should reconsider allowing nonmedical vaccine exemptions because of the potential impact that these exemptions have on public health.