Expert Consensus Messaging as a Lever Against Vaccination Misinformation

The spread of misinformation about vaccines can slow down collective efforts to respond to life-threatening diseases, and thus severely damage public health. Strategies for counteracting misinformation about vaccines include to pre-emptively inform individuals about misinformation before it occurs, to increase their resilience against misinformation. In a pre-registered online experiment, we tested whether pre-emptive expert consensus messaging (H1) or rebuttal by a science advocate only (H2) decreased convincingness of misinformation and increased behavioral intentions to get vaccinated, compared to a control group and whether a combination of both had additive effects (H3). We also tested whether the intervention effects were a function of individual characteristics that link to perceptions of misinformation, namely subject-matter knowledge, conspiracy mentality and need for authenticity. This study was informed by two pilot studies where individuals who perceived expert consensus in favor of vaccination as strong evaluated misinformation as less and rebuttal arguments as more convincing. In the full sample, hypotheses 1-3 were not confirmed. Patterns observed in an additional, non-pre-registered post-hoc analysis of a subsample that correctly answered a preceding manipulation check question reflected our initial hypotheses. Findings will help understanding how pre-emptive communications of scientific consensus can serve as a cost-effective strategy for targeting misinformation before it even occurs. They thus contribute to strengthening societal support for implementing effective and large-scale policies against diseases.