The Relationship Between Political Affiliation, Perceptions of Science and Scientists, and Perceived Safety and Effectiveness of the MMR, Flu, and COVID-19 Vaccines: United States, 2024.

Objectives. To examine the associations between political party identification, perceptions of science and scientists, and perceived safety and effectiveness of the measles, mumps, and rubella, flu, and COVID-19 vaccines. Methods. We used multiple regression analyses to examine survey data collected in November 2024 from a national probability sample of 1763 US adults. We measured perceptions of science and scientists using the Factors Assessing Science's Self-Presentation (FASS) scale, which assesses beliefs that scientists are credible, prudent, and unbiased and that science is beneficial and self-correcting. Results. Respondents perceived the measles, mumps, and rubella vaccine as the safest and most effective (mean safety score = 3.54 [SD = 0.71]; mean effectiveness score = 3.63 [SD = 0.68]) and the COVID-19 vaccine as the least safe and effective (mean safety score = 2.98 [SD = 1.07]; mean effectiveness score = 2.81 [SD = 1.02]). After adjustment for FASS factors, political party identification was associated only with perceptions of the COVID-19 vaccine (P < .001). Associations between political party identification and FASS factors varied by vaccine type. Perceiving science as beneficial was the factor most consistently associated with vaccine evaluations. Conclusions. Republicans are more concerned about the safety and effectiveness of vaccines, with politicization most evident for the COVID-19 vaccine. Public Health Implications. These findings can guide tailored communication strategies addressing vaccine safety and effectiveness concerns among specific audiences. (Am J Public Health. Published online ahead of print September 10, 2026:e1-e9. https://doi.org/10.2105/AJPH.2026.308606).