A meta-analysis of the relationship between vaccine hesitancy and behavior

Abstract Background Despite extensive research on vaccine hesitancy across various scientific domains, its definition and measurement remain inconsistent, resulting in lacking comparison across studies and an unclear relation with vaccine behavior (i.e., accepting, refusing, postponing, or partially vaccinating). Recent work argues that vaccine hesitancy is best understood as a psychological state of indecisiveness in vaccination decisions. This enables crucial comparisons across studies. This meta-analysis uses this definition to clarify the association between vaccine hesitancy and behavior, including potential moderating factors. Methods We conducted a preregistered systematic review and meta-analysis of quantitative studies (2010 onwards) on vaccine hesitancy and behavior. PubMed, Embase, Web of Science, and PsycINFO were searched and the retrieved articles were screened. In addition to the expected variability in the measurement of vaccine hesitancy, we also found variation in how vaccine behavior was defined - particularly in terms of timeliness and completeness of uptake - prompting us to develop four distinct operationalizations. Raw data were requested from authors and obtained in 16 cases. Currently, we are meta-analytically examining the correlation between vaccine hesitancy and behavior, and exploring moderating factors. Results Of 5740 articles, 95 were included. For 10 datasets, preliminary results show that sample sizes range from 66 to 1388, a majority of geographical continents is covered, and the data mainly focuses on childhood vaccinations. The correlation between vaccine hesitancy and behavior ranges from -0.21 to -0.66. Conclusions Preliminary results indicate a negative association between vaccine hesitancy and behavior, as expected. During EPHC, we will present further insights from the meta-analysis. Key messages • This study provides a clean, meta-analytic correlation between vaccine hesitancy (defined as indecisiveness) and behavior, and explores the role of moderators. • Like hesitancy, vaccination behavior is multifaceted. We propose to address timeliness and completeness in future work.