An Epidemiologic Study of Vaccination Exemptions and Pertussis Risk

The incidence of pertussis, a vaccine-preventable disease that can have severe complications in infants, has been increasing in the United States over the past three decades. Vaccine hesitancy and refusal have also increased and are associated with vaccination exemptions, which in turn are associated with outbreaks of vaccine-preventable diseases, including pertussis. Understanding attitudes towards vaccinations and identifying geographic disparities of vaccination exemptions and pertussis risks is useful for guiding control programs. Therefore, the objectives of this study were to: (i) investigate attitudes towards vaccinations; (ii) identify county-level geographic disparities and sociodemographic predictors of vaccination exemptions in Florida; (iii) investigate county-level geographic disparities, temporal changes, and sociodemographic predictors of pertussis risk in Florida between 2010 and 2018.

Qualitative methods were used to investigate attitudes towards vaccinations in the Knoxville area of Tennessee. Spatial patterns of vaccination exemption and pertussis risks were identified using county-level choropleth maps. Tango’s spatial scan statistics were used to identify clusters of pertussis risk, which were displayed in maps. Negative binomial and ordinary least squares regression models were used to investigate predictors of vaccination exemption and pertussis risks, respectively.

Risk perception as well as family and social group attitudes were the primary contributors to vaccination hesitancy. High vaccination exemption risks were observed in Western and Central Panhandle, Northeastern, Central-eastern, Central-western, and South-western coastal counties of Florida. High risks of total vaccination exemptions were observed in counties with high densities of primary care providers, high median income, high percentage of Hispanic population, and high percentage of population with college education. High risks of non-medical exemptions tended to occur in counties with high percentage of white population. Clusters of high pertussis risks were identified in Western Panhandle, Northeastern coast, and along the Western coast. Significant predictors of high county-level pertussis risks were rurality, high median income, and high percentage of females.

The identified drivers of vaccination hesitancy as well as disparities in and predictors of vaccination exemptions and pertussis risks are invaluable in guiding evidence-based health planning, resource allocation, and policy decisions aimed at reducing the burden and disparities in pertussis risk.