COVID-19 Vaccine Coverage Index: Identifying barriers to COVID-19 vaccine uptake across U.S. counties

Mishra, A.; Sutermaster, S.; Smittenaar, P.; Stewart, N.; Sgaier, S.

Importance: The United States is in a race against time to vaccinate its population to contain the COVID-19 pandemic. With limited resources, a proactive, targeted effort is needed to reach widespread community immunity. Objective: Identify county-level barriers to achieving rapid COVID-19 vaccine coverage and validate the index against vaccine rollout data. Design: Ecological study Setting: Population-based Participants: Longitudinal COVID-19 vaccination coverage data for 50 states and the District of Columbia and 3118 counties from January 12 through May 25, 2021. Exposure(s): The COVID-19 Vaccine Coverage index (CVAC) ranks states and counties on barriers to coverage through 28 indicators across 5 themes: historic undervaccination, sociodemographic barriers, resource-constrained health system, healthcare accessibility barriers, and irregular care-seeking behaviors. A score of 0 indicates the lowest level of concern, whereas a score of 1 indicates the highest level of concern. Main Outcome(s) and Measure(s): State-level vaccine administrations from January 12 through May 25, 2021, provided by the Centers for Disease Control and Prevention (CDC) and Our World In Data. County-level vaccine coverage as of May 25, 2021, provided by the CDC. Results: As of May 25, 2021, the CVAC strongly correlated with the percentage of population fully vaccinated against COVID-19 by county (r = -0.39, p=2.2x10-16) and state (r=-0.77, p=4.9x10-11). Low-concern states and counties have fully vaccinated 26.5% [t=6.8, p=1.7x10-7] and 26% (t=22.0, p=2.2x10-16) more people, respectively, compared to their high-concern counterparts. This vaccination gap is at its highest point since the start of vaccination and continues to grow. Higher concern on each of the five themes predicts a lower rate of vaccination at the county level (all p<.001). We identify five types of counties with distinct barrier profiles. Conclusions and Relevance: The CVAC measures underlying barriers to vaccination and is strongly associated with the speed of rollout. As the coverage gap between high- and low-concern regions continues to grow, the CVAC can inform a precision public health response targeted to underlying barriers.