The impact of hypothetical lottery structures on vaccine-hesitant adults' flu vaccination intentions: A conceptual replication of Taber et al. (2023).

Objective: Vaccine hesitancy threatens global health, but vaccination rates for the seasonal flu are often suboptimal. Thus, it is important to develop and optimize interventions to reduce flu vaccine hesitancy. Vaccine lotteries-where chosen winners must be vaccinated to collect a monetary payout-could encourage vaccination through people's perceived likelihood of winning the lottery and anticipated regret. Antecedents of vaccination may also impact vaccine intentions.

Method: Adults from the United States who were unvaccinated for the flu (n = 598) were randomly assigned to read one of 12 scenarios regarding flu vaccine lotteries differing in structure (payout amount and number of winners).

Results: Adjusting for baseline flu vaccination willingness, structures with more money to fewer winners and $100 each to 50,000 winners led to greater vaccination intentions. Structures with larger payouts to fewer winners also generally resulted in lower perceived likelihood of winning and greater anticipated regret. Regression results showed that greater perceived likelihood and anticipated regret, as well as antecedents of greater confidence, less preference for deliberation, and greater collective responsibility about the flu vaccine, were associated with greater postscenario intentions. Secondary analyses found that antecedents of COVID-19 vaccination differed from those of the flu.

Conclusion: Results suggest that vaccine lotteries structured to award greater payout to fewer winners would be most likely to increase flu vaccine uptake, in contrast to a similar study conducted for COVID-19 in which lottery structure did not influence vaccination intentions (Taber et al., 2023). Results have implications for policy-makers designing financial incentive interventions. (PsycInfo Database Record (c) 2025 APA, all rights reserved).