Effectiveness of “naturalness” value-based narrative intervention on vaccination acceptance in two randomized controlled trials

Conventional vaccine risk communication, which emphasizes scientific facts about vaccine or disease risks, often overlooks laypeople's values and fails to increase vaccination acceptance. This study developed and tested a participant-informed, value-embedded narrative intervention to improve vaccination acceptance among Hong Kong parents and adults. Two message types were created: a standard message framing vaccines as a medical technology (Med-Tech) and a naturalness-oriented framing (Immune-Trainer), both incorporated narrative communication and imagination simulation. In Study 1, 631 parents were randomly assigned to control, Med-Tech, or Immune-Trainer groups. The Immune-Trainer group showed more positive affective attitudes, generated more naturalness-related cues, and reported higher intention and uptake of childhood influenza vaccination. Study 2, involving 2261 adults and an additional non-narrative, fact-based-only group, largely replicated these findings except for actual uptake. Immune-Trainer outperformed the fact-based-only messages. Significant effects on vaccination intentions and reported actual uptake were observed for influenza but not for COVID-19 vaccination across both samples.