‘The Pandemic Is a Prisoner’s Dilemma Game’
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She noted, however, that game theory assumes people are rational in their decision-making. Fear can suppress vaccination “to precarious levels insufficient to prevent the spread of an outbreak,” she said.
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Answers to Your Vaccine Questions
With distribution of a coronavirus vaccine beginning in the U.S., here are answers to some questions you may be wondering about:
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- If I live in the U.S., when can I get the vaccine? While the exact order of vaccine recipients may vary by state, most will likely put medical workers and residents of long-term care facilities first. If you want to understand how this decision is getting made, this article will help.
- When can I return to normal life after being vaccinated? Life will return to normal only when society as a whole gains enough protection against the coronavirus. Once countries authorize a vaccine, they’ll only be able to vaccinate a few percent of their citizens at most in the first couple months. The unvaccinated majority will still remain vulnerable to getting infected. A growing number of coronavirus vaccines are showing robust protection against becoming sick. But it’s also possible for people to spread the virus without even knowing they’re infected because they experience only mild symptoms or none at all. Scientists don’t yet know if the vaccines also block the transmission of the coronavirus. So for the time being, even vaccinated people will need to wear masks, avoid indoor crowds, and so on. Once enough people get vaccinated, it will become very difficult for the coronavirus to find vulnerable people to infect. Depending on how quickly we as a society achieve that goal, life might start approaching something like normal by the fall 2021.
- If I’ve been vaccinated, do I still need to wear a mask? Yes, but not forever. Here’s why. The coronavirus vaccines are injected deep into the muscles and stimulate the immune system to produce antibodies. This appears to be enough protection to keep the vaccinated person from getting ill. But what’s not clear is whether it’s possible for the virus to bloom in the nose — and be sneezed or breathed out to infect others — even as antibodies elsewhere in the body have mobilized to prevent the vaccinated person from getting sick. The vaccine clinical trials were designed to determine whether vaccinated people are protected from illness — not to find out whether they could still spread the coronavirus. Based on studies of flu vaccine and even patients infected with Covid-19, researchers have reason to be hopeful that vaccinated people won’t spread the virus, but more research is needed. In the meantime, everyone — even vaccinated people — will need to think of themselves as possible silent spreaders and keep wearing a mask. Read more here.
- Will it hurt? What are the side effects? The Pfizer and BioNTech vaccine is delivered as a shot in the arm, like other typical vaccines. The injection into your arm won’t feel different than any other vaccine, but the rate of short-lived side effects does appear higher than a flu shot. Tens of thousands of people have already received the vaccines, and none of them have reported any serious health problems. The side effects, which can resemble the symptoms of Covid-19, last about a day and appear more likely after the second dose. Early reports from vaccine trials suggest some people might need to take a day off from work because they feel lousy after receiving the second dose. In the Pfizer study, about half developed fatigue. Other side effects occurred in at least 25 to 33 percent of patients, sometimes more, including headaches, chills and muscle pain. While these experiences aren’t pleasant, they are a good sign that your own immune system is mounting a potent response to the vaccine that will provide long-lasting immunity.
- Will mRNA vaccines change my genes? No. The vaccines from Moderna and Pfizer use a genetic molecule to prime the immune system. That molecule, known as mRNA, is eventually destroyed by the body. The mRNA is packaged in an oily bubble that can fuse to a cell, allowing the molecule to slip in. The cell uses the mRNA to make proteins from the coronavirus, which can stimulate the immune system. At any moment, each of our cells may contain hundreds of thousands of mRNA molecules, which they produce in order to make proteins of their own. Once those proteins are made, our cells then shred the mRNA with special enzymes. The mRNA molecules our cells make can only survive a matter of minutes. The mRNA in vaccines is engineered to withstand the cell’s enzymes a bit longer, so that the cells can make extra virus proteins and prompt a stronger immune response. But the mRNA can only last for a few days at most before they are destroyed.
A 2019 investigation using game theory to study vaccination showed that vaccine hesitancy could be explained by a mathy mechanism called “hysteresis.” In general terms, hysteresis occurs when the effects of a force persist even after the force is removed — the response lags. Paper clips exposed to a magnetic field still cling together after the field is turned off; unemployment rates can remain high even in a recovery economy.
Similarly, even after a vaccine is deemed safe and efficacious, uptake rates often remain low.
“The hysteresis effect makes the population hysterical, or sensitive, to the perceived risks of the vaccine,” said Xingru Chen, a doctoral student in mathematics at Dartmouth College, and the paper’s co-author, with her adviser Feng Fu, a mathematician and biomedical data scientist (who recently applied a similar approach to the dilemma of social distancing).
“It boils down to a fundamental problem known as the tragedy of the commons,” Ms. Chen said. “There is a misalignment of individual interests and societal interests.” To overcome the hysteresis effect, she said, vaccination should be promoted as an act of altruism — one’s personal contribution to defeating the pandemic.
A subsequent iteration of the coronavirus game-theory study explored how vaccine compliance affects the number of deaths prevented. If a small subset of the population chooses not to get the vaccine, it affects us all, said Dr. Anand, who is also an author and a poet. Her book “A New Index for Predicting Catastrophes” includes found poems composed of words from her scientific papers.
(One poem, “The Strategy of the Majority, ” was drawn from her first paper on human-environment systems, which inspired the current study. The last line: “the price of finding equilibria is increasing.”)
Sebastian Funk, an infectious disease epidemiologist at the London School of Hygiene and Tropical Medicine, said that the coronavirus study nicely highlighted the importance of assessing how interventions aiming to contain spread during an outbreak can affect human behavior. “Excluding this from models of infectious disease transmission can be a major limitation,” he said.