Sociodemographic and Health-Risk Determinants of COVID-19 Vaccine Booster Preferences and Willingness to Pay in Singapore: Discrete Choice Experiment.

Background: Waning immunity and recurring COVID-19 waves point to the importance of sustained booster vaccination strategies. With repeated boosters needed to sustain population-level immunity, evaluating public preferences for COVID-19 booster vaccination is important for informing future vaccination strategies, as changing perceptions of urgency, threat, and motivation may alter willingness to receive vaccine boosters compared with initial uptake. Objective: This study aimed to explore the public's stated preferences and implicit willingness to pay for COVID-19 vaccine boosters in Singapore and to identify the sociodemographic factors and health-risk acceptance profiles associated with these outcomes. Methods: A discrete choice experiment survey was conducted among the general population in Singapore, recruited from an online panel in June 2022. Discrete choice experiment scenarios presented hypothetical scenarios varying by booster characteristics, including effectiveness, protection duration, and cost, and risks of COVID-19 infection, hospitalization, and death. A 2-stage discrete choice design was used: participants first selected between 2 hypothetical scenarios and then reported real-life booster acceptance of their chosen option. A mixed logit model was used for analyses. We also estimated implicit willingness to pay for vaccine boosters, as well as assessed the associations of sociodemographic factors and health-risk profiles with booster acceptance or hesitancy. Results: A total of 1567 participants were included in the analysis. Overall, respondents preferred boosters that offered a longer duration of protection, particularly under higher risks of COVID-19 infection and death. Respondents were willing to pay S$1.43 for every percentage-point increase in booster effectiveness, S$4.95 (S$1=US $0.77 as of July 10, 2026) per additional month of protection, and an additional S$55.23 for a vaccine booster under the hypothetical worst-case scenario of COVID-19. Younger adults, women, individuals of non-Chinese ethnicity, those without children, people with higher socioeconomic status, individuals who had received 2 or fewer COVID-19 vaccine doses, and those with chronic conditions or on chronic disease medication were more likely to receive a booster. On the other hand, older adults, individuals with lower education or socioeconomic status, those with prior COVID-19 infection, and those exhibiting higher health-risk acceptance were less likely to accept booster vaccination. Conclusions: Our findings demonstrate how vaccine attributes, sociodemographic factors, and health-risk attitudes influence booster acceptance. These insights can guide policymakers in tailoring strategies and communication efforts that address population needs and behavioral drivers to improve booster uptake, address hesitancy, and support sustainable long-term immunization coverage, contributing to adaptive vaccination planning in the ongoing management of COVID-19.