The communicative effects of metaphors for vaccination as a collective health endeavor

In health communication, metaphor can be considered as a reasoning device to let people understand an abstract concept in terms of a concrete one (Lakoff and Johnson 1980; Bowdle and Gentner 2005). Both the positive and negative communicative effects of metaphors have been largely pointed out in a variety of medical fields, from oncology (Semino et al. 2016, 2018) to mental health (Frezza and Zoccolotti 2019). The use of metaphors in vaccine communication has been less considered, though it might be crucial to let people understand vaccination as an important collective health phenomenon. A previous study (Scherer et al. 2015) focused on the communicative effects of conventional metaphors for vaccination, but not specifically on novel metaphors deliberately used to explain the concept of population immunity in vaccination. We hypothesized that metaphors used to explain vaccination as a collective phenomenon could improve the communicative aims of pro-vaccination texts in many respects, ranging from understandability to trust in expertise. We designed a study to test the hypothesis: two groups of participants were presented with a text about vaccination as a collective phenomenon, described in either literal or metaphorical terms. They were asked to evaluate the text on different communicative aspects from both an individual and a collective point of view. The results confirmed the hypothesis that metaphor is an effective reasoning device and that it also enhances the overall communicative effects of the message, in terms of understandability, persuasion, feeling of control over the health situation, trust in expertise, and uptake of experts’ advice. However, the results show that this effect is significantly nuanced in the individual vs. collective response type.