Motivating COVID-19 Vaccination through Persuasive Communication: A Systematic Review of Randomized Controlled Trials

Vaccination is a vital defense against COVID-19 infections and outbreaks, yet vaccine hesitancy poses a significant threat to pandemic response and recovery. We conducted a systematic review of published randomized controlled trials (N = 47) assessing the persuasive effects of COVID-19 communication on COVID-19 vaccine acceptance. Individual vs. collective appeals and gain vs. loss frames are among the most frequently assessed message features, but they generally do not make a difference in persuasion. Normative messages that highlight higher (vs. lower) prevalence of vaccine acceptance are more persuasive. Message sources overall have limited impact on COVID-19 vaccine acceptance, but sources that have a shared identity with the message receivers tend to be persuasive. More engaging message channels such as interactive chatbots and videos are promising communication tools but are generally under-utilized and under-studied. Compared to no communication or irrelevant communication, COVID-19 vaccine messages generally have a small advantage in increasing COVID-19 vaccine acceptance. Messages that include 1) vaccine safety and/or efficacy information; 2) collective appeals combined with embarrassment appeals; and 3) political leaders' vaccine endorsement are among the most effective messaging strategies. There is no evidence of any backfire effects of COVID-19 vaccine messages. We discuss the implications of our findings for persuasive message design in pandemic vaccine communication.