The determinants of vaccine hesitancy remain complex and context specific. Betrayal aversion occurs when an individual is hesitant to risk being betrayed in an environment involving trust. In this pre-registered vignette experiment, we show that betrayal aversion is not captured by current vaccine hesitancy measures despite representing a significant source of unwillingness to be vaccinated. Our survey instrument was administered to 888 United States residents via Amazon Mechanical Turk in March 2021. We find that over a third of participants have betrayal averse preferences, resulting in an 8-26% decline in vaccine acceptance, depending on the betrayal source. Interestingly, attributing betrayal risk to scientists or government results in the greatest declines in vaccine acceptance. We explore an exogenous message intervention and show that an otherwise effective message acts narrowly and fails to reduce betrayal aversion. Our results demonstrate the importance of betrayal aversion as a preference construct in the decision to vaccinate.
