Bandwagoning, free‐riding and heterogeneity in influenza vaccine decisions: An online experiment

Abstract

Nudge'-based social norms messages conveying high population influenza vaccination coverage levels can encourage vaccination due to bandwagoning effects but also discourage vaccination due to free-riding effects on low risk of infection, making their impact on vaccination uptake ambiguous. We develop a theoretical framework to capture heterogeneity around vaccination behaviors, and empirically measure the causal effects of different messages about vaccination coverage rates on four self-reported and behavioral vaccination intention measures. In an online experiment, N = 1365 UK adults are randomly assigned to one of seven treatment groups with different messages about their social environment's coverage rate (varied between 10% and 95%), or a control group with no message. We find that treated groups have significantly greater vaccination intention than the control. Treatment effects increase with the coverage rate up to a 75% level, consistent with a bandwagoning effect. For coverage rates above 75%, the treatment effects, albeit still positive, stop increasing and remain flat (or even decline). Our results suggest that, at higher coverage rates, free-riding behavior may partially crowd out bandwagoning effects of coverage rate messages. We also find significant heterogeneity of these effects depending on the individual perceptions of risks of infection and of the coverage rates.

Herd immunity versus self-interest motives and norms effects on influenza vaccination intention.

“…Thus, more than two norm levels should be used in studies aiming to test this variable effect. The inverted-U pattern offers preliminary insights to reconcile both studies showing bandwagoning effects and free-riding effects (Allen et al, 2009;Betsch et al, 2017;Galizzi et al, 2022;Graupensperger et al, 2021;Hershey et al, 1994;Ibuka et al, 2014;Quinn et al, 2017;Romley et al, 2016;Vietri et al, 2012). This might be the case particularly if vaccination was presented to subjects as conferring herd immunity or if the benefits for others were salient in participants' minds when answering the questions.…”

“…Some studies have not found an association between the perceived level of social norms and vaccination adoption (Lazić et al, 2021; Salali et al, 2022; Sinclair & Agerström, 2023). On the other hand, some found a positive association, that is, bandwagoning (higher norm increase adoption), either with vaccination adoption (Allen et al, 2009; Quinn et al, 2017) or intention (Galizzi et al, 2022; Graupensperger et al, 2021; Hershey et al, 1994; Romley et al, 2016). Some studies have shown a negative effect (Betsch et al, 2017; Galizzi et al, 2022; Ibuka et al, 2014; Vietri et al, 2012), that is, free riding, a phenomenon occurring when one’s contribution does not seem necessary to prevent the spread of the virus, and adoption decrease with norm increase.…”

“…The pattern in their result followed this curve (i.e., vaccination intention was higher when the norm was at 60% compared to 30% or 90%), but the differences between groups were not significant. Galizzi et al (2022) also made the hypothesis of an inverted-U shape and varied the norm level from 10%, 25%, 50%, 65%, 75%, 85% to 95%. They showed that vaccination intention increased with the norm up to 75% (the bandwagoning effect) and then remained flat or even declined at the very high norm levels, suggesting free riding.…”

Compliance in the public versus the private realm: Economic preferences, institutional trust and COVID‐19 health behaviors

“…This analysis contributes to the literatures on the predictors of individual‐level outside‐the‐lab rule and norm compliance in economics, law, political science and psychology in a variety of contexts, including health behaviors during epidemics or pandemics (e.g., Algan et al., 2021; Blair et al., 2017; Böhm et al., 2016; Brodeur, Gray, et al., 2021; Galizzi et al., 2022). Furthermore, we contribute to the more specific and recently emerging literature on health behaviors in times of COVID‐19.…”

Happiness predicts compliance with preventive health behaviours during Covid-19 lockdowns

“…We contribute to this growing body of evidence by studying whether life satisfaction predicts compliance with preventive health behaviours, complementing existing evidence on compliance that looks primarily at socio-demographic, economic, or attitudinal factors 12 – 14 , incidental factors like meteorological conditions 15 , or the way information on health risks and others’ behaviours is provided 16 . In particular, we look at the unique setting of Covid-19 lockdowns, in which governments and health officials around the world have been asking their citizens to substantially change their behaviours for prolonged periods of time, by practising physical distancing and staying at home, amongst others.…”