The relative effects of determinants on Chinese adults’ decision for influenza vaccination choice: What is the effect of priming?

To assess the relative effects of altering different factors (attributes) related to adults’ decision for influenza vaccination choice, and whether priming modifies these relative effects.Chinese adults were randomly allocated to either a control condition (non-risk related video), or one of the three health risk-priming conditions (disease (influenza) risk video, intervention (vaccine) risk video, or non-specific (air pollution) risk video), each comprising ∼200 participants, prior to a discrete choice experiment survey. Mixed logit modelling estimated the relative effects of pre-determined attributes influencing vaccination choice.Across all four conditions, for determining vaccination choice, Vaccine Efficacy had a greater effect than social cues (community vaccination coverage rate (CVCR) and doctors’ advice) but social cues can compensate for the effect of “uncertain” vaccine safety; influenza case-fatality ratio (CFR) became dominantly important among all included attributes when it reached 20%; vaccination preference increased when a CVCR changed incrementally from 5% to 60% but declined thereafter when the CVCR reached 80%. Compared with Control participants, a CVCR increased by 80% had a smaller effect for participants primed by intervention risk on vaccination choice, while the effect of influenza risk relative to vaccine risk increased following disease risk priming.While increasing confidence on vaccine efficacy is more important for influenza with less severe consequences, highlighting disease consequences becomes increasingly important when its CFR increases, for promoting vaccination uptake. For a new vaccine with uncertain safety, involving doctors and early vaccine takers to validate vaccine safety should be important. Brief exposure to influenza/vaccine risk didn’t increase the effect of specific risk on vaccination choice but may change the relative weight of disease versus intervention risk when individuals make trade-off for vaccination decision. Free riding on herd immunity may increase when community vaccination coverage is high particularly following intervention risk priming.