Changes in Confidence, Feelings, and Perceived Necessity Concerning COVID-19 Booster.

The COVID-19 booster first became available to all adults in the U.S. in November 2021 and a bivalent version in September 2022, but a large population remains booster-hesitant; only 17% of Americans have obtained the updated vaccine as of June 2023. We conducted two cross-sectional surveys in 2021 and 2022 ( = 1889 and 1319) to determine whether changes in booster-related feelings or perceptions had occurred and whether they altered vaccination rates over time. We found that both positive and negative emotions had grown stronger between the two years, with the prevalence of annoyance increasing the most (21.5% to 39.7%). The impact of trust on booster intention more than doubled (OR = 7.46 to 16.04). Although perceived risk of infection decreased, more participants in 2022 indicated uncertainty or unwillingness to obtain a new booster than in 2021, while the proportion refusing a booster remained constant at 22.5%. Confidence in the COVID-19 vaccine and feelings of hope from the booster motivated acceptance; both were stronger predictors of booster receptivity than prior vaccination history. Our findings signal a need to rebuild trust by informing people of their continued risk and appealing to positive, especially optimistic emotions to encourage booster uptake. Future research should explore longitudinal trends in behavior and feelings toward new booster doses and the impact of prolonged vaccine hesitancy on infection rates.