Fact or fiction: An experiment on how information sources and message framing influence vaccine risk perception

In view of the growing disinformation about vaccines on social media since the beginning of the Covid-19 pandemic, effective communication strategies encouraging vaccine uptake are needed. We conducted an experiment through an online, preregistered survey to explore which types of information sources are more trusted by the population regarding the risks of the Covid-19 booster, and which types of message frames are more effective in influencing the perception of risks for children. We surveyed a representative sample composed of 1,800 Spaniards in June 2022. The two depen-dent variables were respondents' perceptions of (1) the Covid-19 booster vaccine effectiveness and (2) the safety of the Covid-19 vaccine for children. Participants were randomly exposed to different messaging regarding these vaccines, with different sources of information (scientific consensus, scientific dissensus, governmental, influencers and medical doctors), and different message framing (pro-and anti-vaccine storytelling and pro- and anti-vaccine scientific data). Additionally, some respondents who did not receive any messaging formed a control group. Our findings suggest that di-fferent information sources and frames can influence people's risk perception of vaccines. The source 'medical doctors' had a positive effect on risk perception of the Covid-19 booster vaccine (p < 0.05), and pro-vaccine messages, in the form of both storytelling and scientific expository frames, had a positive effect on respondents' risk perception of the vaccine for children (p < 0.1 and p < 0.05, respectively). On the one hand, male and older respondents rated booster vaccines as more effective than female and younger respondents. On the other hand, right-wing respondents believed vaccines are somewhat less safe for children than left-wing respondents. These findings might support the development of strategic communication in vaccination programmes by public health departments to improve immunization rates in the general population. The practical and theoretical implications are discussed.