Abstract
It has become clear throughout the COVID-19 pandemic that decisions concerning vaccination were not as straightforward as anticipated with individuals displaying varying levels of vaccine hesitancy. In the wake of this, it is important to consider how people make decisions and what factors may influence them. It is well known that people discount future gains at significantly higher rates than generally assumed, and far in excess of those used in health decision making. This can lead to policy headaches for governments and health professionals alike as higher rates of discounting have been found to lead to poorer health choices and a lower likelihood to engage in preventative healthcare and screenings. Previous studies have also found that discounting was steeper in unvaccinated individuals and that time preferences had significant effects on immunization decisions. While it has been identified that the safety and side effects of the vaccine are a major concern for those considering vaccination, how these factors interact with discounting and competing policy outcomes has not yet been explored.
To understand this, we will use a Discrete Choice Experiment (DCE) and discounting questionnaire to explore if vaccine hesitancy is explained by discounted utility and how discount rates impact vaccination and policy preferences. The DCE was carried out in 21 countries and designed to elicit preferences on trade-offs between vaccine effectiveness, risk of side effects, duration of protection, time to market approval, origin of vaccine manufacturer, and health policy restrictions. Two discounting tests, in the style of a Multiple Price List developed by Coller & Williams, were also included in the questionnaire to understand how participants discounted gains between today and 3-months in the future and also between 3-months and 6-months in the future. The total sample size for the questionnaire was 51,000 respondents and was representative of the age, gender and geographical distribution for the countries sampled. A multinomial logistic regression will be used to model the trade-offs between the options selected by the participants and how discounting impacts the likelihood they would choose one option over another.
Understanding the impact of discounting on these trade-offs is important for policymakers going forward for both the continuing COVID-19 pandemic and any future pandemics. It is expected that high discounting will lead to adverse decision making due to a preference for immediate rewards and a lower value for the future. This preference for immediate gains, or present bias, could lead to individuals accepting sub-par options now rather than waiting for the best overall health outcome for themselves and/or others. Conversely the opposite is also true, where without any immediate incentives, those with high discount rates would be expected to delay vaccination, putting themselves and the community at unnecessary risk. It is key to consider if people will see a vaccine to be the point of utility maximization at a personal level if the government is to achieve their goal of complete vaccination. Especially as vaccination rates have increased the benefits to getting vaccinated quickly fall off, exacerbating the problem.