Vaccine Misinformation and Social Determinants of Vaccine Intentions in a Pandemic

Objective: To examine how vaccine misinformation shapes perceivedsocial norms and assess their mediating role in vaccination intentionsduring pandemics, an underexplored mechanism in misinformation'sinfluence on vaccine decisions.Methods: In a pre-registered online experiment, UK residents (n=332)were randomly assigned to either a misinformation or control condition ina hypothetical pandemic scenario. I measured changes in vaccinationintentions, first-order normative beliefs (perceptions of others'vaccination intentions), and second-order normative beliefs (perceptionsof others' beliefs about vaccine safety) before and after exposure. Causalmediation analysis using inverse odds ratio weighting assessed theindirect effects of misinformation through changes in normative beliefs.Results: The pre-post comparison revealed that vaccine intentionsdeclined 2.5% more in the misinformation condition compared to control(p = 0.024, d = 0.24). In the misinformation group, average vaccineintentions dropped from 62.4% to 59.3%, while the control group showedminimal change from 60.8% to 60.2%. Changes in first-order normativebeliefs mediated 39.52% of misinformation's total effect on vaccinationintentions.Conclusions: The findings reveal that vaccine misinformation operatesthrough dual pathways: directly affecting individual beliefs whilesimultaneously distorting perceptions of social consensus aboutvaccination.