Though available for all age groups in the US, only about half of those vaccinated have obtained a COVID-19 booster. Similar to the unvaccinated, those vaccinated-but-not-boosted may reduce the effectiveness of widespread viral protection. Booster hesitancy differs from general vaccine hesitancy yet remains less researched. We examined booster perceptions across vaccination status using qualitative methodologies. Four focus groups and 11 individual interviews (total n = 32) revealed nuanced changes and differences compared to the first-dose decision. Booster hesitancy stemmed from questions and surprises. Most vaccinated participants accepted the booster, though to varying degrees: enthusiastically with feelings of appreciation and added confidence, passively as an intuitive next step, indifferently following recommendation-"primed" by the yearly flu shot, and reluctantly with worries. The vaccinated-but-not-boosted group expressed confusion about the need for a new shot and discontentment as to why it was not communicated from the start, which coincided with their uncertainty about ending the pandemic. Inadvertently, booster recommendations further polarized non-vaccinated participants, augmenting their skepticism of the original dosages' efficacy or necessity and intensifying their distrust of the government. The findings illuminate the need for adjusting vaccination promotions to better tailor communications (e.g., distinguishing its benefits from the first vaccine and emphasizing the continued risk of COVID-19 spread). Future researchers should further explore the vaccine-accepting-yet-booster-hesitant groups' motivations and risk perceptions to reduce booster rejection.
Keywords: SARS-CoV-2; acceptance; attitudes; communication strategies; confidence; decision sciences; health behavior; immunization; public health; qualitative studies; risk perception; vaccine hesitancy.