Unravelling the psychology of vaccination decision-making in the context of preventing against respiratory infectious diseases : emotions, values, and communication strategies

Abstract

Background: Vaccination is one of the most important public health strategies for controlling a pandemic or infectious disease outbreak . However, its success depends on achieving sufficiently high population coverage. Vaccine hesitancy (VH), characterized by indecisiveness about vaccination, continues to threaten efforts to effectively control vaccine-preventable infectious diseases. The prevailing “knowledge deficit” models in the literature addresses VH by advocating education as primary solutions of which the effectiveness was limited. This study aimed to examine when and how vaccination decision-making could deviate from the “rational man” processes, explore the underlying emotions and values that contribute to vaccination decision-making, and design and test affect-based and value-based vaccine risk communication for tackling VH. Methods: This thesis first reported two population-based observational studies using serial cross-sectional surveys aimed at uncovering psychological processes and contextual factors that contribute to age-specific and socioeconomic disparities in COVID-19 vaccine acceptance. In addition, two qualitative studies were conducted. The first study focused on vaccine-hesitant older adults to explore their vaccination decision-making during the pandemic, while the second study examined vaccine-hesitant parents to identify the underlying value influencing their vaccination decisions. Furthermore, two experimental studies were conducted to test the effectiveness of novel vaccine risk communication strategies for improving parents’ acceptance for their children’s vaccination. The first experiment introduced an affect-based risk communication intervention, using positive imagination to mitigate negative information processing and VH. The second experiment developed a value-based risk communication designed to align messages with parents’ preference for naturalness to improve their vaccine-related attitudes and children’s actual uptake of seasonal influenza vaccines (SIV). Principal findings: The two population-based observational studies revealed that older adults, individuals with greater socioeconomic vulnerabilities, and those experiencing heightened psychological distress were more prone to negatively process vaccine-related information, resulting in disparities in COVID-19 vaccination acceptance. The qualitative studies provided deeper exploration of the psychological roots influencing vaccine-hesitant individuals’ heuristic-based vaccination decision-making. For older adults, psychological roots (e.g., negative perceptions of aging) contributed to biased information processing. This bias was compounded by a lack of decisional support from doctors, family, and government, reinforcing their VH and resistance. The qualitative study with parents revealed that concerns about vaccines often stemmed from a deeply rooted preference for naturalness. Building on these psychological insights, the experimental studies employed emotional and value-related cues aligned with individuals’ psychological motivations. The affect-based communication strategy effectively mitigated negativity biases in information processing, enhancing trust in vaccine information and reducing safety concerns. The value-based communication strategy improved parents’ affective attitudes, mental representation, and intention to vaccinate children against seasonal influenza, leading to increased actual uptake of SIV in children. Conclusions: This research underscored the critical role of psychological processes in vaccine information processing and decision-making. The studies consistently suggested that VH was often driven by heuristic-based decision-making processes, highlighting the need for strategies that deeply investigate lay beliefs and align information design with psychological roots to enhance the effectiveness of vaccine risk communication.