Global spatio-temporal distribution of coronavirus disease 2019 vaccine hesitancy between 2020 and 2022: A meta-analysis

Objective: Vaccine hesitancy is a major barrier to high coronavirus disease 2019 (COVID-19) vaccine coverage. To synthesize global research on COVID-19 vaccine hesitancy, a meta-analysis was conducted to provide scientific evidence for understanding its spatial and temporal variations and influencing factors. Methods: We searched the PubMed, Web of Science, and Embase databases for studies published in English between January 2020 and December 2023 and included cross-sectional and cohort studies with study populations that included the general adult population aged >= 18 years and provided quantitative data on COVID-19 vaccine acceptance or hesitancy. We used the Preferred Reporting Items for Systematic Reviews and Meta- Analysis elements and guidance for abstracting and assessing data quality and validity. Two groups of investigators independently extracted the study characteristics, including the outcome variable (the vaccine hesitancy rate). Our meta-analysis used a random-effects model. The outcome of interest was COVID-19 vaccine hesitancy. The included studies were divided into two categories based on their definitions of COVID-19 vaccine hesitancy. Definition 1 combined vaccination behavior and willingness, and Definition 2 was based solely on willingness to vaccinate. Results: 855 studies were included in the final analytical dataset; 121 met Definition 1, and 734 met Definition 2. There were 277,285,178 participants in the included studies. In studies meeting Definition 1, hesitancy rates increased annually: 18.8 % in 2020, 29.1 % in 2021, and 30.8 % in 2022. However, in studies that met Definition 2, the hesitancy rates remained at 35 %. African studies reported the highest hesitancy rates globally (42.0 %), whereas European studies reported the lowest (16.5 %). Furthermore, there was a temporal association between mortality trends and COVID-19 hesitancy because the monthly cumulative death peaks coincided with lower hesitancy peaks. Conclusion: COVID-19 vaccine hesitancy increased across the continent during 2020-2022 and might be influenced by misinformation, policy changes, and public fatigue. Demographic factors like age, gender, and education also play a key role in vaccine hesitancy. The link between vaccine hesitancy and pandemic severity highlights the need for timely and effective public health responses.