When outbreaks of vaccin-prefentable diseases such as measles occur despite There are very effective vaccines availableIt is easy to conclude that parents who do not vaccinate their children are miserable, or prey to wrong information.
As professors with expertise in vaccine policy And health economyWe claim that the decision not to vaccinate is not just over incorrect information Or hesitation. In our opinion it is about game theoryA mathematical framework that helps to explain how reasonable people can make choices that collectively lead to results that endanger them.
Game theory reveals that vaccine hesitation is not moral failure, but simply the predictable outcome of a system in which individual and collective stimuli are not properly matched.
Game theory meets vaccines
Game theory investigates how people make decisions when their results depend on what others choose. In his research into the subject, Nobel Prize Mathematician John Nashdepicted in the film A beautiful mindshowed that individual rational choices in many situations do not automatically create the best results for everyone.
Vaccination decisions perfectly illustrate this principle. When a parent decides whether, for example, his child should vaccinate his child, they weigh the Minor risk of side effects of vaccine against the Risks of the disease. But here it is crucial insight: the risk of illness depends on what other parents decide. When almost everyone vaccinates, herd of immunity– The vaccination of enough people – the spread of the disease will stop. But as soon as the herd of immunity has been reached, individual parents can decide that not vaccinating is the less risky option for their child.
In other words, because of a Fundamental tension Between individual choice and collective well -being, only relying on individual choice cannot achieve no goals for public health.
This makes vaccine decisions fundamentally different from most other health decisions. If you decide whether you want to use medication for high blood pressure, your outcome will only depend on your choice. But everyone is connected to vaccines.
This mutual connection has played dramatically in Texas, where the biggest outbreak of American measles In a decade. As the vaccination percentages fell into certain communities, the disease – opposite eliminated in the US – was reduced. The vaccination rate of one province fell from 96% to 81% in just five years. Considering that About 95% of people in a community Must be vaccinated to achieve herd -immunity, the deterioration created perfect conditions for the current outbreak.
This is no coincidence; Game theory is set in real time. When vaccination rates are high, it does not seem rationally to every individual family, but when enough families make this choice, collective protection collapses.
The Free-Rider Problem
This dynamic creates what economists one Free-Rider Problem. When vaccination percentages are high, a person can benefit from herd immunity without even accepting the minimum vaccinous risks. Game theory predicts something surprising: Even with a hypothetically perfect vaccine – Faultless efficacy, zero side effects – profitable vaccination programs will never achieve 100% coverage. As soon as the coverage is high enough, some rational individuals will always choose to be free riders who benefit from the herd of immunity supplied by others.
And when the rates fall, As they have, dramaticIn the past five years, disease models predict exactly what we see: the return of outbreaks.
Game theory reveals a different pattern: for highly contagious diseases, vaccination percentages fall tend to fall quickly after safety problems, While recovery occurs much slower. This too is a mathematical characteristic of the system because decline and recovery have different stimulation structures. When worrying about the safety organizations, many parents are worried at the same time and stop vaccinating, causing vaccination to fall quickly.
But recovery is slower because it requires both the trust of trust and the problem of the free Rider has to overcome the parent await others to vaccinate first. Can cause small changes in perception Big behavioral shifts. Media -Attention, Social Networks and Health Reports All influence these perceptions, which may move communities to or away from these critical thresholds.
Maths also predicts How people’s decisions about vaccination can cluster. While parents perceive the choices of others, local norms develop, so the more parents skip the vaccine in a community, the more others will probably follow this example.
Game theorists refer to the resulting bags of low vaccine intake as Sensitivity clusters. With these clusters, diseases can continue to exist, even if the total vaccination rates seem sufficient. A 95% over the entire state or national average can mean uniform coverage of a vaccine, which would prevent outbreaks. Alternatively it may mean that some areas with almost 100% coverage and others with dangerously low rates that make local outbreaks possible.
No moral failure
All this means that the dramatic fall in vaccination rates was predicted by game theory, and therefore more a reflection of system vulnerability than a moral failure of individuals. Moreover, it can blame parents for making selfish choices too by the faulty by making them more defensive And less chance of reconsidering their views.
Much more useful would be approaches that the Tensions between individual and collective interests And that works with, instead of against, the mental calculations that inform how people make decisions in interconnected systems.
Research shows that communities that experience outbreaks respond differently To report vaccination as a community problem versus messages that implies moral failure. In a 2021 study of a community with falling vaccination rates, approaches that recognized the sincere concerns of parents Although emphasizing the need for community protection parents were 24% more likely to vaccinate, reduced approaches that emphasized personal responsibility or implicit selfishness their willingness to consider it.
This confirms what game theory predicts: when people think that their decision -making is under a moral attack, they are often more deeply rooted in their positions instead of more open for change.
Better communication strategies
Insight into how people weigh vaccin risks and benefits Better approaches of communication. For example, it is clear that it can be clear to convey risks: the 1-on-500 mortality rate of measles Much heavier than the extremely rare serious side effects of vaccine. That may sound clear, but it often lacks in the public discussion. Various communities also need different approaches: areas with a high vaccination need help to stay on course, while areas with low vaccination have to be rebuilt.
Consistency is extremely important. Research shows that when health experts Give conflicting information or change their messagePeople become a suspicious person and decide to pay vaccines. And dramatic Shocking tactics about diseases can be counterproductive By pushing people to extreme positions.
Making vaccination decisions visible within communities-through-means of community discussions and reporting at school level, where possible to help Set positive social standards. When parents understand that vaccination protects vulnerable members of the community, such as babies who are too young for vaccines or people with medical conditions, this helps the gap between Individual and collective interests.
Healthcare providers remain the Most trusted source of vaccine information. When providers understand the dynamics of game theory, they can tackle the worries of parents more effectively, and acknowledge that for most people hesitation arises from the weighing risks instead of opposite vaccines.
Y. Tony Yang is a beneficiary professor in health policy and associated dean George Washington University.
Avi Dor is a professor in health policy and management at George Washington University.
This article has been re -published from The conversation Under a Creative Commons license. Read the Original article.
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