Seatbelts and Raincoats, or Banks and Castles: Investigating the Impact of Vaccine Metaphors

"...scientists, doctors, and public health officials often use metaphors to explain how vaccines work and to address common questions, concerns, and misconceptions. However, the effectiveness of these metaphors has not been convincingly demonstrated empirically."



Metaphors are tools for explanation and persuasion that have frequently been used to address misconceptions and hesitancy about vaccines. The impact of framing a concept with a metaphor has been studied in a variety of ways, providing insights into the cognitive, affective, and social-pragmatic factors that influence the potency of metaphorical messages. Using a between-subject, pretest/posttest design, this study investigated the impact of explanatory metaphors on people's attitudes toward vaccines.



The researchers recruited participants online in the United States (N = 301) and asked them to provide feedback on a (fictional) health messaging campaign, which was organised around responses to five common questions about vaccines: (i) How do vaccines work? (ii) Is "natural immunity" better than the immunity provided by a vaccine? (iii) Are vaccines that are developed quickly safe? (iv) Why should I take a vaccine if I am personally at low risk for the illness? (v) Why get a vaccine if it isn't 100% effective? All participants completed a 24-item measure of their attitudes towards vaccines before and after evaluating the responses to the five questions.



The researchers created three possible response passages for each vaccine question: Two responses included explanatory metaphors adapted from real-world source materials; a baseline response provided the same information but did not include an explanatory metaphor (i.e., a literal response). Examples of responses involving metaphors are: your body as a medieval castle surrounded by an army of viruses (where vaccines train your body's troops); your immune system as the high-quality security measures surrounding a bank (where vaccines train your body's security measures); vaccines as the flight simulation programmes that airplane pilots are trained on before they attempt to fly a plane through bad weather conditions; vaccines as the fire drills students do in schools; being vaccinated like wearing a waterproof raincoat, even though 100% protection from getting wet is not possible.

Participants were randomly assigned to receive either all metaphors or all literal responses. They rated each response on several dimensions. Finally - advancing a new methodology for metaphor research and mindful of the influence of social networks on vaccine attitudes - the researchers asked participants how they would respond to a friend who asked them one of the five common questions above about vaccines (e.g., Question 5: "Why get a vaccine if it isn't 100% effective?") and to provide the response they would give their friend by typing into a blank text box.



This analysis suggests that certain metaphors may help or hinder communications about a particular topic. For example, using a bank or castle metaphor to explain how vaccines work may make a message easier to understand, though it does not appear to impact how informative or persuasive the message seems in relation to a comparable literal message. Results showed that participants in both conditions rated most messages as being similarly understandable, informative, and persuasive, with a few exceptions. Participants in both conditions also exhibited a similar small - but significant - increase in favourable attitudes towards vaccines from pre- to posttest.



Notably, participants in the metaphor condition provided longer free-response answers to the question posed by a hypothetical friend, suggesting that metaphors "seem to provide additional vocabulary and imagery that can be exploited in social relationships - in this case, communicating with a friend." Three metaphors were reused by more than 20% of participants: castle (22%), bank (23%), and raincoat (27%). The metaphors used in response to Questions 1 ("How do vaccines work?") and 5 ("Why get a vaccine if it isn't 100% effective?") were reused most often. Notably, most participants did not reuse the metaphors they had read. The higher word count produced in the metaphor condition suggests that exposure to metaphors results in participants being more fluent in producing explanations.



Thus, for participants in this study, communicating with extended explanatory metaphors did not make a vaccine health message any more or less effective than communicating via a comparable literal message overall. The few exceptions, though, may be useful for researchers and public health communicators who need to make choices about particular metaphors in the future. For example, the quantitative findings suggest that invoking a war metaphor involving a national mobilisation scenario might be particularly ineffective in explaining why low-risk individuals should be vaccinated. In contrast, the castle metaphor, which involves a different war-related scenario, was found to be potentially useful in communicating how vaccines work. This differential highlights the importance of considering specific scenarios and their associated narratives in developing metaphorical frames.



Taken together, the findings suggest that: (i) Brief health messaging passages may have the potential to improve attitudes towards vaccines; (ii) metaphors neither enhance nor reduce this attitude effect; and (iii) metaphors may be more helpful than literal language in facilitating further social communication about vaccines.



The researchers conclude: "Fully addressing vaccine education and hesitancy will take more than a simple 10-minute online intervention. However, we believe our study represents one cost-effective method for systematically generating and testing messages that healthcare workers and everyday citizens might use in interpersonal, on-the-ground communications. We hope that these findings will both aid and inspire future research on the functions of metaphor in explanation in general and vaccine hesitancy in particular."