Rain on the Parade of Influenza Vaccine Hesitancy

Abstract: Background: Following the protection motivation theory (PMT), a lack of risk perception is one of the reasons for differences in vaccine uptake ( Rogers, 1975 ). When the risk for diseases like seasonal influenza is underestimated, protective measures such as vaccination are used less. Aims: In this paper, we propose that the sequelae approach, which involves providing information about the severe complications of diseases, can influence people’s risk perceptions and their intention to vaccinate. This is in comparison to providing merely information about the disease itself. Method: Three preregistered online experiments (2017–2019) were conducted to examine whether risk perceptions and vaccination intentions increase when (1) information about sequelae is presented as statistical texts or narratives (vs. not presented at all), (2) known or unknown sequelae (myocardial infarction vs. sepsis), and (3) different target populations (e.g., health literacy) are considered. Results: An internal meta-analysis showed that the sequelae approach increases intentions ( SMD = .39.20;.59) but not risk perception ( SMD = .09−.10;.27). Unknown and known sequelae had an equal impact on vaccination intentions. None of the strategies (narratives vs. statistical texts, sequelae type) produced adverse reactions in people with low health literacy. In addition, no evidence was found for boomerang effects. Limitations: Even though our research was based on PMT, we cannot add evidence on self-efficacy or response efficacy as influential factors. Conclusion: Although increased risk perception is not the primary mechanism behind the sequelae approach, the results support the use of this strategy in educational interventions that target vaccine hesitancy.