The effects of informational nudges on herpes zoster vaccination intentions in China: a survey experiment

Despite the availability of effective vaccines, vaccination uptake remains suboptimal, particularly for “low-awareness” vaccines. Whether informational nudges can increase vaccination intention in such contexts, and among whom they are most effective, remains unclear. Using herpes zoster vaccination (HZV) as a case study, we conducted a pre-registered randomized survey experiment among 4730 unvaccinated adults aged ≥40 years in China. Participants were randomly assigned to receive one of several informational nudge messages, including clinical evidence, expert recommendations, descriptive social norms, and gain- or loss-framed messages, before reporting their intention to receive HZV on a 0-10 scale. Compared with a no-message control group, messages emphasizing clinical evidence, descriptive social norms, and gain-framed family protection significantly increased vaccination intentions. By contrast, expert recommendation messages and loss-framed messages were not associated with higher intentions. Direct comparisons within intervention categories revealed no significant differences between clinical evidence and expert recommendation messages or between weak and strong descriptive norm messages, whereas gain-framed messages produced modestly stronger effects than loss-framed messages in some specifications. Subgroup analyses revealed stronger responses among females, urban residents, individuals with lower perceived socioeconomic status, and those reporting better health. Our findings suggest that informational nudges can increase intentions to receive a “low-awareness” vaccine, but their effects depend on message content and population characteristics. The results provide the potential of targeted communication strategies for improving vaccination uptake.