Prebunking messaging to inoculate against COVID-19 vaccine misinformation: an effective strategy for public health

Background: Vaccination coverage needs to reach more than 80% to resolve the COVID-19 pandemic, but vaccine hesitancy, fuelled by misinformation, may jeopardize this goal. Unvaccinated older adults are not only at risk of COVID-19 complications but may also be misled by false information. Prebunking, based on inoculation theory, involves ‘forewarning people [of] and refuting information that challenges their existing belief or behavior’. Objective: To assess the effectiveness of inoculation communication strategies in countering disinformation about COVID-19 vaccines among Canadians aged 50 years and older, as measured by their COVID-19 vaccine intentions. Method: Applying an online experiment with a mixed pre–post design and a sample size of 2500 participants, we conducted a national randomized survey among English and French-speaking Canadians aged 50 years and older in March 2021. Responses to two different disinformation messages were evaluated. Our primary outcome was the intention to receive a COVID-19 vaccine, with attitudes toward COVID-19 vaccine a secondary outcome. The McNemar test and multivariate logistic regression analysis on paired data were conducted when the outcome was dichotomized. Wilcoxon sign rank test and Kruskal–Wallis were used to test difference scores between pre- and post-tests by condition. Results: Group comparisons between those who received only disinformation and those who received the inoculation message show that prebunking messages may safeguard intention to get vaccinated and have a protective effect against disinformation. Conclusion: Prebunking messages should be considered as one strategy for public health communication to combat misinformation.