State-Level Variations and Factors Associated with Adult Vaccination Coverage: A Multilevel Modeling Approach.

Abstract

BackgroundAdult vaccination rates in the USA are generally low and fall short of public health goals.ObjectivesOur aim was to evaluate the effect of state-level characteristics on adult vaccination coverage in the USA.MethodsThis study was a cross-sectional, retrospective analysis of 2015–2017 Behavioral Risk Factor Surveillance System data, conducted from March to October 2019 and including seasonal influenza; pneumococcal; tetanus, diphtheria, and acellular pertussis (Tdap); and herpes zoster (HZ) vaccines. Multilevel logistic regression models examined interstate vaccination coverage variability and assessed the impact of state-level characteristics, with model-adjusted coverage estimated.ResultsModel-adjusted vaccination coverage varied by state, with 35.1–48.1% coverage for influenza (2017), 68.2–80.8% for pneumococcal (2017), 21.9–46.5% for Tdap (2016), and 30.5–50.9% for HZ (2017). Characteristics associated with vaccination included state-level insurance coverage, pharmacists’ vaccination authority, vaccination exemptions, and adult immunization information systems participation, as well as individual-level measures of income and education. After adjusting for these factors, substantial interstate heterogeneity remained.ConclusionsModel-adjusted coverage was generally low and varied by state. A small number of state-level characteristics partially explained interstate coverage variability. This and future research assessing additional state characteristics may help determine policies most likely to increase adult vaccination.Supplementary InformationThe online version contains supplementary material available at 10.1007/s41669-021-00262-x.