Economic and Behavioral Influencers of Vaccination and Antimicrobial Use

"The prevalence of vaccine hesitancy and antimicrobial overuse warrants consideration from policy makers because of the individual, societal, and economic costs that they entail."

The growing trend in vaccine hesitancy and/or refusal globally has implications for the acceptance and coverage of a potential vaccine against COVID-19. Meanwhile, the overuse and misuse of antibiotics have led to increasing rates of drug resistance. This paper investigates the co-existence of vaccine hesitancy and antibiotic overuse in the same population of young children in an attempt to understand why one modality (antibiotics) is seen as safe and effective, and the other (vaccination) is seen as potentially hazardous by some. It considers the drivers shaping the use of vaccines and antibiotics in the context of three factors - risk perceptions, individual incentives, and social norms and group dynamics - with the ultimate goal of informing policymaking.

Section 2 examines the role of risk perception. Evidence suggests that in the United States (US), for example, the perceived risk of vaccine use in the general population is far greater than the actual probability of adverse vaccine-associated events. Likewise, across several countries, even when antibiotic use is unlikely to have a significant benefit for infection prognosis, a large proportion of patients have been shown to desire a prescription. The paper discusses game-theoretic models of behaviour and prospect theory to explain why individual decisions often deviate from predictions of expected utility theory, or the classic risk-benefit model of health behaviour. Cognitive biases, such as the availability heuristic, as well as the framing of choices and individual or social factors such as emotion and trust, also play a role.

Section 3 looks at the issue of individual incentives and external consequences. For instance, individuals may choose to vaccinate at a rate that is lower than optimal for society since herd immunity protects them from disease, even in the absence of vaccination. Factors such as the perceived cost and benefits of intervention and values and sentiments of social responsibility may shape individuals' medical decisions. Furthermore, the transboundary nature of disease spread and emergence of antibiotic resistance have prompted research, discussed here, into the conditions for cooperation between decision-making bodies and how this affects individual behaviour.

Section 4 examines the types of norms and community histories that govern vaccine- and antibiotic-related health behaviours. Descriptive norms include behaviours that are performed by community members (i.e., what is done), while injunctive norms describe behaviours that receive approval from the community (i.e., what ought to be done). For example, a study on Tongolese mothers found that the communication of a pro-immunisation message by the chief, as well as vaccination by the chief himself (a descriptive norm), led to increases in vaccination by mothers for themselves and their children. However, social norms can have negative effects on vaccine uptake if they are anti-vaccination or more generally anti-medicine and anti-establishment in nature.

The paper provides a vaccination-related case study to explore the motivations underlying norm conformity, which can be different for individuals entering a community (social newcomers) and long-standing community members. (In short, social newcomers are highly incentivised to conform (e.g., to norms of non-vaccination) as a way of building solidarity and securing their positions. For long-standing community members, on the other hand, non-vaccination may become an unconscious behaviour or a deeply-rooted belief. In the latter case, individuals are susceptible to a variety of cognitive biases.) In addition, norms play a role in antibiotic use in two ways: by affecting patient expectations and by affecting prescriber approaches. The paper discusses these in the context of the complementary and alternative medicine (CAM) community.

Section 5 estimates the risks and costs to individuals and societies associated with vaccination, vaccine hesitancy, antimicrobial use, and antimicrobial resistance at the societal and individual levels. To contextualise these ideas, the paper presents two case studies: one of influenza vaccine refusal and one of measles vaccine hesitancy. It concludes with a specific example of antimicrobial resistance and its consequences. For instance, the social isolation that methicillin-resistant Staphylococcus Aureus (MRSA) patients may face due to fear of contagion can create psychological harm and stigmatisation.

Section 6 proposes a series of policy interventions in an effort to curb vaccine hesitancy and antimicrobial overuse, including:

• Direct manipulation of cost or supply of vaccines and antibiotics - e.g., imposing fines or offering rewards.
• Changes to medical and prescriber practices - e.g., changing the way medical information is presented, which has been found to play a role in the magnitude of the risk perceived by the patient. In one of the most basic forms of such an intervention, pneumococcal vaccination rates among high-risk patients were found to increase when simple educational information was provided and patient-physician communication about the vaccine was encouraged.
• Nudging and influences to social behaviour - e.g., informing individuals that others are choosing to vaccinate, which can increase their uptake.
• Educational campaigns and media coverage - e.g., emphasising the societal consequences of vaccine refusal and antibiotic overuse, thereby setting social expectations for responsible health behaviour, and regulating media coverage of outlier cases of negative vaccine consequences, perhaps by enforcing that equal coverage of cases of the diseases they are preventing be broadcast.

Thus, this paper has outlined how a variety of misperceptions about risk contributes, in part, to the imbalance of vaccine uptake and antimicrobial use relative to their socially optimal levels of consumption. Complications arise from the multifactorial nature of information flow, involving prescribing physicians, patients, pharmacists, the government, and so on, and the cognitive biases that reinforce misperceptions. Social norms of non-vaccination also appear to push individuals toward vaccine hesitancy and refusal. Furthermore, specific racial and ethnic communities may have unique relationships to vaccines for a variety of historical reasons, which will be important for policymakers to consider.

Among the communication-related suggestions offered in conclusion: Non-governmental organisations (NGOs) can engage in nudging through directed campaigns, but the efficacy of these initiatives depends on characteristics of the messages that they portray. Based on the successes and failures of previous campaigns, it appears that these messages should be informed by social norms theory. Finally, it is recommended that any interventions be coordinated between regional actors to match the global nature of pathogenic spread and antimicrobial resistance.

In conclusion, this review of the personal, societal, and economic factors affecting vaccine hesitancy and antimicrobial overuse may shape efforts to foster uptake of the COVID-19 vaccine.