Effectiveness of tailored public health messages for vulnerable populations: A randomised controlled trial

OBJECTIVES: This study aimed to investigate the impact of 'who' delivers a health message (general practitioner or community representative), and the 'visual stimulus' (animation or talking head) used on influencing attitudes toward safe behaviours in the context of the COVID-19 pandemic, across six vulnerable population subgroups STUDY DESIGN: A 'helix' randomised controlled trial with 2x2 factorial design. METHODS: Participants (40 per subgroup) were randomly allocated within their subgroup to an intervention sequence. They completed a factorial, counter-balanced allocation of four intervention combinations across four safe behaviour contexts. Exposure to each intervention was followed by online survey questions investigating intention to undertake, and encourage family and friends to undertake, the context-specific behaviour using a 5-point Likert-style scale RESULTS: A total of 358 participants responded to requests to participate in the study, of whom 298 (83%) fully completed and 58 (16%) partially completed surveys. Participants were more likely to report higher intention to perform COVID-safe behaviours when exposed to animation compared to talking head visual stimuli (Coef = -0·12, 95% CI = -0·22 to -0·01, p = 0·03; β = -0.12, 95% CI -0.22 to -0.01, p = .03, animation > talking head) There was no main effect of 'who' provided the message; however, several interaction effects were noted across population subgroups for each intervention. CONCLUSION: The approach best suited for different vulnerable subgroups varies across each, indicating a one-size-fits-all approach should not be used and is inequitable. However, the additional costs and time-delays that would be encountered in preparing subgroup-specific materials also warrant consideration.