Preferences for COVID-19 Vaccines:Systematic Literature Reviewof Discrete Choice Experiments

Background: Vaccination can be viewed as comprising the most important defensive barriers to protect susceptible groupsfrom infection. However, vaccine hesitancy for COVID-19 is widespread worldwide.Objective: We aimed to systematically review studies eliciting the COVID-19 vaccine preference using discrete choiceexperiments.Methods: A literature search was conducted in PubMed, Embase, Web of Science, Scopus, and CINAHL Plus platforms inApril 2023. Search terms included discrete choice experiments, COVID-19, and vaccinesand related synonyms. Descriptivestatistics were used to summarize the study characteristics. Subgroup analyses were performed by factors such as high-incomecountries and low- and middle-income countries and study period (before, during, and after the pandemic wave). Quality appraisalwas performed using the 5-item Purpose, Respondents, Explanation, Findings, and Significance checklist.Results: The search yield a total of 623 records, and 47 studies with 53 data points were finally included. Attributes weregrouped into 4 categories: outcome, process, cost, and others. The vaccine effectiveness (21/53, 40%) and safety (7/53, 13%)were the most frequently reported and important attributes. Subgroup analyses showed that vaccine effectiveness was the mostimportant attribute, although the preference varied by subgroups. Compared to high-income countries (3/29, 10%), a higherproportion of low- and middle-income countries (4/24, 17%) prioritized safety. As the pandemic progressed, the duration ofprotection (2/24, 8%) during the pandemic wave and COVID-19 mortality risk (5/25, 20%) after the pandemic wave emerged as2 of the most important attributes.Conclusions: Our review revealed the critical role of vaccine effectiveness and safety in COVID-19 vaccine preference. However,it should be noticed that preference heterogeneity was observed across subpopulations and may change over time