Inject or Infect: How Do the Default Effect, Anticipated Regret, and Decision Roles Predict Vaccination Willingness

The WHO defines vaccine hesitancy as one of the ten biggest threats to global health nowadays. To contribute to finding a solution for vaccine hesitancy, this study aims at gaining new insights on the influence of the default effect, anticipated regret, and decision roles on vaccination willingness. In an online study, a sample of 187 participants (70.0% female, 87.7% Dutch, 79.7% high-educated) receives information concerning colon cancer and a possible vaccine. The results show that presenting vaccination as a default option (i.e. vaccination is the standard in the form) does not influence the vaccine uptake compared to a control group. The anticipated regret people indicate to experience for getting side-effects and colon cancer, however, does significantly predict vaccination willingness (B = -0.36, p = 0.00; B = 0.16, p = 0.03, respectively). Furthermore, people rather vaccinate themselves than their child (B = -0.61, p= 0.01). This correlation appears to be mediated by anticipated regret: the levels of anticipated regret for getting side-effects and colon cancer are higher for the child than the self-decision (p = 0.00 and p = 0.01, respectively). Finally, gender and willingness to take risks towards faith in others also show a significant and relevant correlation with vaccination willingness. These results suggest that anticipated regret explains why people rather vaccinate themselves than their children and that the default effect cannot change vaccination willingness. Due to academic and societal importance, more research should be done to fill the gaps in knowledge related to vaccine hesitancy.