​Summary: Partisan differences in attitudes toward the COVID-19 pandemic and toward the appropriateness of local policies requiring masks, social distancing, and vaccines are apparent in the United States. Previous research suggests that areas with a higher Republican vote share may experience more COVID-19 mortality, potentially as a consequence of these differences. In this observational study that captured data from a majority of U.S. counties, researchers compared the number of COVID-19 deaths through October 31, 2021, among counties with differing levels of Republican vote share, using 2020 presidential election returns to characterize county political affiliation. Authors’ analyses controlled for demographic characteristics and social determinants likely to influence COVID-19 transmission and outcomes using state fixed effects.

Findings: Authors found a positive dose-response relationship between county-level Republican vote share and county-level COVID-19 mortality. Majority Republican counties experienced 72.9 additional deaths per 100,000 people relative to majority Democratic counties during the study period, and COVID-19 vaccine uptake explains approximately 10 percent of the difference. Findings suggest that county-level voting behavior may act as a proxy for compliance with and support of public health measures that would protect residents from COVID-19.