Politics in Public Health: Growing Partisan Divides in COVID-19 Vaccine Attitudes and Uptake Post-2021 Presidential Inauguration

Objectives: To investigate whether the 2021 U.S. presidential inauguration contributed to a widening of partisan divides in COVID-19 vaccine attitudes and uptake. Methods: We leverage the presidential inauguration as a natural experiment and analyze data from the Household Pulse Survey and CDC vaccination records. Using a difference-in-differences framework with continuous treatment, we examine how the transition differentially affected state-level vaccine refusal rates and county-level vaccination rates, based on varying levels of partisanship as measured by the Trump–Biden vote gap. Results: Following Biden’s inauguration, vaccine refusal declined more in pro-Biden states. Distrust in government and vaccines accounted for approximately 80% of the interstate variation. County-level analysis revealed that for every 1 percentage point increase in Trump’s vote share over Biden’s, counties experienced an additional 0.515%–2.674% decline in vaccination rates among adults aged 65+. These effects were more pronounced in politically loyal and high-turnout counties. Conclusion: The presidential transition appears to have widened partisan divides regrading COVID-19 vaccines. These findings highlight the need for depoliticized health messaging and bipartisan strategies to mitigate the influence of partisanship on public health.