The Effects of Narrative- Versus Science-oriented Messages on Parents’ Attitude Towards MMR Vaccine: The Moderation of Conspiracy Beliefs in Vaccination

Research background: Vaccine hesitancy is ranked as a top ten global health threat by the WHO. One of the most skeptical childhood vaccines is MMR vaccine. Having a high level of conspiracy beliefs is one of the strongest psychological predictors contributing to vaccine hesitancy and anti-vaccination. The current study aims to: 1) compare the effectiveness of scientific- versus narrative-based messages in promoting positive outcomes related to MMR vaccination tendency, and 2) understand the effectiveness of the TPB versus Affect Heuristic theory in explaining vaccination behavior among VHPs.Method: A total of 438 VHPs were randomly assigned into one of the four experimental messages: no exposure (n = 107), scientific (n = 111), narrative (n = 109), hybrid (i.e., narrative and scientific) (n = 111). Outcomes include vaccination intention, vaccine hesitancy, perceived risk toward measles and MMR vaccination, perceived benefit toward MMR vaccination, positive affect toward vaccination, attitudes toward vaccination and measles, subjective norms, and behavioral control toward MMR vaccination. ANOVA, multiple regression analysis, and the Johnson Neyman technique were implemented. Results: ANOVA suggested significant differences among the four message conditions in predicting vaccination intention, positive affect, and perceived benefits. Pairwise comparisons using Bonferroni adjustments suggested only exposure to hybrid messages significantly increased vaccination intention, positive affect, and perceived benefit toward vaccination compared to the control condition. However, the scientific message and narrative found no differences from each other, from the control group, and from the hybrid message. Considered general conspiracy belief (GCB) as the moderator, narrative message significantly increased MMR vaccination intention and positive affect only among those with a low to average GCB. No interaction effects were found for other interactions and outcomes. Unsurprisingly, when vaccination conspiracy beliefs was included as the moderator, none of the messages was effective in predicting the positive outcomes. Discussion: Hybrid and narrative messages promoting MMR vaccination are effective among general VHPs and VHPs with GCB, respectively. Affect heuristic theory is more effective in explaining the behavioral change of VHPs than the TPB. Additionally, tailoring messages according to individuals' information processing styles could be an effective health communication strategy