Understanding Vaccine Hesitancy: Three Essays on the Role of Risk, Trust and Cognitive Characteristics in Vaccine Acceptance

Vaccine prophylaxis can undoubtedly be classified among the most important medical discoveries of the last century. The World Health Organization estimates that each year vaccinations prevent between two and three million deaths. Despite vaccines’ safety and effectiveness, vaccine hesitancy, the delay or refusal of vaccines despite their availability, is a re-emerging issue in high income countries. In this thesis I examine this issue pre- and post-COVID-19 pandemic, investigating the main predictors of vaccine hesitancy and highlighting the cognitive processes involved in individual's decision-making. In the theoretical section, I rely on contributions from sociology, economics and public health studies to build a framework enlightening the most relevant predictors of vaccine acceptance, the perceived risk of infectious diseases and the trust in the vaccination process. Through recent development in cognitive sciences, I reframe the issue showing the importance of considering the way individuals perceive, process and retrieve information in developing an informed analysis of vaccine acceptance. In the first empirical chapter, I investigate whether it is possible to identify subgroups in the population characterized by different world-views based on different patterns of the relationship between perceived risk and trust measures. I further assess whether such partitioning hides different levels of vaccine acceptance and whether it also entails a mean of social stratification. In the second empirical chapter I further explore how certain cognitive processes, analytic and intuitive cognition, might be connected to a differential in vaccine acceptance. Furthermore, I highlight individuals’ qualitatively complex perceptions of risk, and I suggest how enhancing the attention on cognitive processes and affective concerns might be a key to addressing vaccine hesitancy. In the third empirical chapter, I investigate vaccine hesitancy during the COVID-19 pandemic. I exploit rich comparative longitudinal data and analyze the association between risk perceptions, trust, and willingness to be vaccinated at three different levels: between individuals, between countries and within countries over time. In this chapter, I underline the importance of disentangling the main relationships of this thesis at different levels of analysis, and stress that vaccine acceptance is a multifaceted topic that could involve issues far beyond its own boundaries.