Background: Democrats and Republicans in the United States were divided on their COVID-related risk perceptions and their adoption of preventive measures (e.g., getting vaccinated). Based on moral foundations theory and the matching hypothesis, this study hypothesized that parents with a Democratic affiliation would be persuaded by messages featuring a harm/care or a fairness moral appeal, whereas parents with a Republican affiliation would be persuaded by messages featuring an authority or ingroup loyalty appeal.

Method: An experiment was conducted among 567 parents with children aged 5-11, whereby each participant was randomly assigned to read one of the four moral appeals or a control message. Each participant then completed a questionnaire.

Results: The results showed that, in general, the moral appeals did not interact with parents’ political affiliations, and the moral appeal messages did not significantly increase the parents' risk perceptions or vaccine uptake intent for their children. Additional analysis showed that trust in government and future orientation were strong predictors of parents’ risk perceptions and vaccine uptake intent, whereas COVID fatigue was a weak predictor of their message evaluation.

Conclusion: Moral framing in persuasive messages may have limited effects on a health problem widely known to the public. Instead, participants' internalized value orientations and personal differences may be more predictive of their attitudes and adoption of preventive measures.