On the effect of uncertainty on personal vaccination decisions

Optimal self-protection and health risk perceptions: Exploring connections between risk theory and the Health Belief Model

In this contribution to the longstanding risk theory debate on optimal self-protection, we aim to enrich the microeconomic modeling of self-protection, in the wake of Ehrlich and Becker (1972), by exploring the representation of risk perception at the core of the Health Belief Model (HBM), a conceptual framework extremely influential in Public Health studies (Janz and Becker, 1984). In our two-period model, we highlight the crucial role of risk perception in the individual decision to adopt a preventive behavior toward a generic health risk. We discuss the optimal prevention effort engaged by an agent displaying either imperfect knowledge of the susceptibility (probability of occurrence) or the severity (magnitude of the loss) of a health hazard, or facing uncertainty on these risk components. We assess the impact of risk aversion and prudence on the optimal level of self-protection, a critical issue in the risk and insurance economic literature, yet often overlooked in HBM studies. Our results pave the way for the design of efficient information instruments to improve health prevention when risk perceptions are biased.

Navigating the uncertainty: A novel taxonomy of vaccine hesitancy in the context of COVID-19

Vaccine hesitancy remains a significant and evolving public health challenge. The COVID-19 pandemic has created a unique decision context with significant uncertainty caused by the novelty of the disease being targeted, unfamiliarity with the vaccines being offered, misinformation, and strong handed government measures. In an effort to extend our understanding of vaccine hesitancy to the high uncertainty decision environment presented by COVID-19, we present a novel taxonomy of the determinants of vaccine hesitancy, based on an inductive analysis of qualitative data gathered during the COVID-19 pandemic. We report on focus group data from a purposive sample of 18 Canadians with varying sociodemographic characteristics and COVID-19 vaccination attitudes. An inductive thematic analysis of this data reveals eight core themes related to vaccine hesitancy: values, trust, social environment, personal anecdotes, environmental fluctuation, prior knowledge, perceived risk & systems of care. We explore these core themes as well as 25 sub-themes, contrasting them with previous models of vaccine hesitancy and suggesting potential strategies for public health professionals.

COVID-19 vaccination in pregnancy: ambiguity in decision-making

Throughout the COVID-19 pandemic, pregnant women/people were identified as an at-risk group of severe COVID-19 disease. Consequently, vaccine uptake among this group became a public health priority. However, the relationship between pregnancy and vaccination decision-making is complex, and the heightened uncertainty and anxiety produced through the pandemic further exacerbated this immunization decision. This study explores COVID-19 vaccination decision-making during pregnancy in Aotearoa New Zealand by using an online story completion survey tool. Ninety-five responses were received and analysed using thematic analysis where ambiguity was a core facet within and across stories. Three ambiguities were identified, including who makes the decision (agential), what the risks are (risk) and how immunity to this threat can be best achieved (immunity). We discuss the implications of this ambiguity and how the strong desire to protect the baby persisted across accounts. The recognition of the rather persistent ambiguity in vaccination decision-making helps conceptualize influencing factors taken into account in a more nuanced manner for further research, public health campaigns and health professionals. Future public health campaigns can consider redistributing responsibility for vaccination decision-making in pregnancy, traverse an either/or perspective of 'natural' and 'artificial' immunity-boosting and consider how risk is perceived through anecdotes and viral immediacy.

How to reduce vaccination hesitancy? The relevance of evidence and its communicator

Even though the immediate urgency of the COVID-19 pandemic seems to have passed, many countries did not reach the vaccination rates they initially aimed for. The stagnation in vaccine uptake during the height of the pandemic presented policy makers with a challenge that remains unresolved and is paramount for future pandemics and other crises: How to convince the (often not insubstantial) unvaccinated proportion of the population of the benefits of a vaccination? Designing more successful communication strategies, both in retrospect and looking ahead, requires a differentiated understanding of the concerns of those that remain unvaccinated. Guided by the elaboration likelihood model, this paper has two objectives: First, it explores by means of a latent class analysis how unvaccinated individuals might be characterized by their attitudes towards COVID-19 vaccination. Second, we investigate to what extent (i) varying types of evidence (none/anecdotal/statistical) can be employed by (ii) different types of communicators (scientists/politicians) to improve vaccination intentions across these subgroups. To address these questions, we conducted an original online survey experiment among 2145 unvaccinated respondents from Germany where a substantial population share remains unvaccinated. The results suggest three different subgroups, which differ regarding their openness towards a COVID-19 vaccination: Vaccination opponents (N = 1184), sceptics (N = 572) and those in principle receptive (N = 389) to be vaccinated. On average, neither the provision of statistical nor anecdotal evidence increased the persuasiveness of information regarding the efficacy of a COVID-19 vaccine. However, scientists were, on average, more persuasive than politicians (relatively increase vaccination intentions by 0.184 standard deviations). With respect to heterogeneous treatment effects among the three subgroups, vaccination opponents seem largely unreachable, while sceptics value information by scientists, particularly if supported by anecdotal evidence (relatively increases intentions by 0.45 standard deviations). Receptives seem much more responsive to statistical evidence from politicians (relatively increases intentions by 0.38 standard deviations).

Risk aversion and COVID-19 vaccine hesitancy

We here investigate the role of risk aversion in COVID-19 vaccine hesitancy. The theoretical effect is ambiguous, as both COVID-19 infection and vaccination side-effects involve probabilistic elements. In large-scale data covering five European countries, we find that vaccine hesitancy falls with risk aversion, so that COVID-19 infection is perceived as involving greater risk than is vaccination.