Trade-Offs between Vaccine Effectiveness and Vaccine Safety: Personal versus Policy Decisions.

Objective: We aimed to investigate whether individuals' trade-offs between vaccine effectiveness and vaccine safety vary if they are asked to consider the perspective of a policymaker making decisions for others compared with the decisions they would make for themselves.

Method: A web-enabled discrete choice experiment survey was administered between 1 April and 1 May 2022 to participants recruited from the general population of two Southeast Asian countries (Indonesia and Vietnam). In each country, 500 participants were randomly assigned to make decisions regarding coronavirus disease 2019 (COVID-19) vaccines for others as a policymaker or in a personal capacity for their own use. Vaccines were characterized by three attributes: (1) effectiveness of the vaccine in reducing infection rate; (2) effectiveness of the vaccine in reducing hospitalization among those infected; and (3) risk of death from vaccine-related serious adverse events. A mixed logit model was utilized for analyses.

Results: Based on the attributes and levels used in this study, the most important vaccine attribute was the risk of death from vaccine-related adverse events, followed by effectiveness in reducing infection rate and hospitalizations. Compared with personal decisions, the mean probability of choosing a vaccine was (1) lower, and (2) more sensitive to the changes in risk of death from adverse events in policy decisions (p ≤ 0.01).

Conclusions and relevance: Our results suggest that, in the face of an infectious disease pandemic, individuals are likely to be more risk-averse to vaccine-related deaths when making decisions for others as a policymaker than they would for themselves.