Priming with social benefit information of vaccination to increase acceptance of COVID-19 vaccines.

Vaccine hesitancy can be heightened due to increasing negative reports about vaccines. Emphasizing the social benefits of vaccination may shift individual attention from individual to social benefit of vaccination and hence promote prosocial vaccination. In six rounds of a population-based survey conducted over one major community epidemic of coronavirus disease 2019 (COVID-19) in Hong Kong from June to November 2020, we manipulated the question asking about acceptance of a COVID-19 vaccine with or without emphasizing the social benefit of vaccination against COVID-19 (prosocial priming) and monitored the changes of vaccine confidence by news media sentiment on vaccines. Population-weighted percentages of accepting COVID-19 vaccines by priming condition and vaccine confidence were compared across survey rounds. Logit regression models assessed the main effect of prosocial priming and the modification effects of vaccine confidence and perceived personal risk from COVID-19 on acceptance of COVID-19 vaccines. We found that prosocial priming significantly increased acceptance of COVID-19 vaccines across all survey rounds except for Round 3 when incidence of COVID-19 reached a peak. Vaccine confidence significantly declined in Round 6 when news media sentiment on vaccines became predominantly negative. The effect of prosocial priming on promoting vaccine acceptance was significantly greater in participants with low vaccine confidence and those perceiving the severity of COVID-19 to be mild/very mild. Our study suggests that packaging vaccination against COVID-19 as a prosocial behaviour can help overcome low vaccine confidence and promote prosocial vaccination particularly when disease incidence temporarily declines and the public perceive low severity of COVID-19.