Vaccination under pessimistic expectations in clinical trials and immunization campaigns

Abstract

We provide one of the first formalizations of a vaccination campaign in a decisiontheoretic framework. We analyse a model where an ambiguity-averse individual must decide how much effort to invest into prevention in the context of a rampant disease.We study how ambiguity aversion affects the effort and the estimation of the vaccine efficacy in clinical trials and immunization campaigns. We find that the behaviours of individuals participating in a clinical trial differ from individuals not participating. Individuals who are more optimistic toward vaccination participate more in trials. Their behaviours and efforts are also affected. As a result, because vaccine efficacy depends on unobserved behaviours and efforts, the biological effect of the vaccine becomes difficult to evaluate. During the scale-up phase of a vaccination campaign, provided that vaccine efficacy is established, we show that vaccine hesitancy may still be rational.

Epidemics, vaccines, and health policy

“…The economics of vaccines is a recurrent theme in this Special Issue and the articles by d'Albis et al (2023), Sorensen (2023), and Amir et al (2023) all address, directly or indirectly, different facets of this important issue. More specifically, all three articles propose settings and results that shed light on some rational or positive aspects of the key issue of vaccine hesitancy, which was one of the central and enduring challenges faced by national and international health authorities during the recent COVID‐19 crisis (also see Federico et al, 2022).…”

“…The seven articles may be divided along the broad categorization by area of economics: five of them take a microeconomics perspective (Amir, et al, 2023; Higgins & Sabarwal, 2023; d'Albis, et al, 2023; Samad et al, 2023; Sorensen, 2023) and thus join similar studies published in the previous Special Issue (e.g., Azémar et al, 2022). The other two articles are grounded in a macroeconomic overlapping‐generations framework (Davin et al, 2023; Marchiori & Pierrard, 2023).…”

“…D'Albis et al (2023) provide a decision‐theoretic argument to explain this issue. Since Geoffard and Philipson (1997), it has been known that disease eradication is not a reachable target when individuals act according to their own interests.…”