Herd Immunity Versus Self-Interest Motives and Norms Effects on Influenza Vaccination Intention

• Published in: Health psychology 2024-03, Vol.43 (3), p.237-245
• Main Authors: Moussaoui, Lisa S., Heiser, Neele H., Desrichard, Olivier
• Format: Article
• Language: English
• Subjects: Communication strategies; Female; Human; Humans; Immunity; Immunity (Disease); Immunity, Herd; Immunization; Influenza; Influenza Vaccines; Influenza, Human - prevention & control; Intention; Male; Mass media; Motivation; Norms; Self interest; Sensitivity analysis; Social Norms; Uptake; Vaccination; Vaccination Attitudes; Vaccines; Vignettes
• ISSN: 0278-6133; 1930-7810
• DOI: 10.1037/hea0001357

Objective: Promoting vaccine uptake is challenging. This research aimed to experimentally test the effect of communication strategies on influenza vaccine uptake intention. We hypothesized that the effect of descriptive norm level (10%-50%-90% of others vaccinated) on intention would vary according to whether the benefits are focused on the individual (self-interest motives) or others (herd-immunity motives). In particular, we predicted that low and high levels of norms would be detrimental in the herd-immunity condition (inverted-U pattern). In contrast, intention should increase linearly with the norm in the self-interest condition. Method: A representative sample of the Swiss population answered a survey containing vignettes manipulating norms (within-subjects variable) and motives (between-subjects variable, randomized). Their intention to receive a flu shot was measured for each situation. Results: As expected, a significant simple quadratic effect of norm was obtained in the herd-immunity condition. No linear effect was found in the self-interest condition. A main effect of motives was found: The intention was higher in the herd-immunity condition than in the self-interest condition. Sensitivity analysis showed that our results are robust, except for the simple quadratic effect in the herd-immunity condition. Conclusions: Herd-immunity motive is more motivating to induce intention to vaccinate against influenza. The effect of norms appears to depend on the motive, and average levels of norms seem to be more motivating than very low and very high levels. The way vaccination is presented can influence adoption rates, and this should be considered when vaccination rates are communicated in the media. Objetivo: Promover la adopción de vacunas es un desafío. Esta investigación tuvo como objetivo probar experimentalmente el efecto de las estrategias de comunicación sobre la intención de adopción de la vacuna contra la influenza. Hipotetizamos que el efecto del nivel de norma descriptiva (10%-50%-90% de los demás vacunados) sobre la intención variaría si los beneficios se centran en el individuo (motivos de interés propio) o en otros (motivos de inmunidad colectiva). En particular, predijimos que niveles altos y bajos de normas serían perjudiciales en la condición de inmunidad colectiva (patrón de U invertida). Por el contrario, la intención debería aumentar linealmente con la norma en la condición de interés propio. Método: Una muestra representativa de la