In the first year of its availability, 84.2% of US adults received at least one dose of COVID-19 vaccine. Progress in COVID-19 vaccination slowed after April 2021, and millions of Americans remain unvaccinated. New research in the American Journal of Preventive Medicine finds wide geographic variance in vaccine uptake and identifies the underlying behavioral and social drivers that factor into the decision to remain unvaccinated. The findings suggest that improving COVID-19 vaccine confidence may not be solved by a “one-size-fits-all solution.”