Experimental Vignettes.

It is possible that the negative attitudes toward COVID-19 vaccination developed by some people, such as self-identified Republicans, might spill over toward other vaccines. We conducted a survey experiment to investigate if mentioning COVID-19 vaccine in messages encouraging seasonal flu vaccination will negatively affect people’s attitudes toward receiving a flu vaccine. The experiment was embedded in a survey fielded in South Dakota in April 2024. Participants were registered voters in the state. We used difference-of-means tests and logistic regression to analyze the data. Results showed no statistically significant differences between the participants in control and treatment groups regarding the likelihood of receiving a flu vaccine (OR: 1.012, CI: 0.594 - 1.724) or their belief in the safety of the flu vaccine (OR: 1.333, CI: 0.707- 2.511). We observed the same patterns when we only looked at Republicans. Attitudes toward flu vaccination were primarily driven by peoples’ current flu vaccination status. We found that mentioning COVID-19 vaccines in flu vaccination messages did not negatively affect people’s attitudes toward flu vaccine. Public health workers and officials might not need to shy away from mentioning COVID-19 vaccines when communicating other vaccines.