OBJECTIVES: Despite routine recommendations, adult uptake of influenza, pneumococcal, pertussis, and zoster vaccines in the United States is low. To inform development of evidence-based vaccination interventions, this study sought to evaluate inter-state variability and better understand local factors influencing adult vaccination coverage.

METHODS: Logistic regression models were employed to estimate state-level adult vaccination coverage adjusted for individual-level characteristics using Behavioral Risk Factor Surveillance System data. States were ranked according to the sum of each state’s calculated z-score for each vaccine’s model-adjusted coverage, providing a composite metric across all four vaccines. Further considering the states ranked at the extremes, we then conducted a targeted review of state immunization websites and published literature to describe facilitators/barriers and interventions targeting adult vaccination, using the Social Ecological Model as a guiding theoretical framework to categorize interventions by level of influence on vaccination.

RESULTS: Based on calculated z-scores, New Jersey, Florida, Illinois, Mississippi, and New York were ranked as low coverage states, while Minnesota, Washington, Colorado, Vermont, and New Mexico were ranked as high coverage states. All interventions reported on state immunization websites were implemented at the institutional or policy level, with immunization information systems most frequently reported (n=10 states). Only a subset of states reported quality improvement programs (n=6) and standing order interventions (n=4). Other common interventions were school immunization laws and state-purchased vaccines. All interventions from the literature (n=12 interventions) targeted improving vaccination at the institutional, interpersonal, or intrapersonal level. Data on state-specific vaccination facilitators/barriers were not identified.

CONCLUSIONS: There is substantial inter-state variability in adult vaccination coverage in the United States. Existing data provide very limited insight on local facilitators/barriers or interventions impacting adult vaccination. Further efforts to bridge this information gap are critical towards developing targeted interventions to increase coverage. Collection of qualitative data from local stakeholders may provide further insights.