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OPINION

How to determine your personal risk once vaccinated

The key question I ask myself: Should the worst happen, how will I feel about the decision I made?

Some people wore masks in the Public Garden and some did not on April 30 after Governor Baker eased the outdoor mask mandate.
Some people wore masks in the Public Garden and some did not on April 30 after Governor Baker eased the outdoor mask mandate.Suzanne Kreiter/Globe Staff

You’re fully vaccinated, probably excited at the prospect of resuming pre-coronavirus pandemic activities, and looking at public health guidelines to help you decide what is safe and what is risky. It can be confusing. As an epidemiologist, I’m often asked which activities are safe. I tell people that I can’t answer the question for them, but I can help them answer it for themselves.

The key question I ask myself before engaging in any activity that carries a risk of COVID-19 infection is: Should the worst happen (I or my loved one contracts COVID-19), how will I feel about the decision I made? The answer depends on two factors: the level of transmission risk inherent in the activity — the degree of close contact, the number of people involved, the setting (indoor versus outdoor, for instance), the prevalence of COVID-19 in the locale, and the immune status (vaccinated, COVID-19 recovered, or neither) of the people involved — and, crucially, the role that activity plays in promoting the mental or physical health and well-being of the people involved. I want those I would be interacting with to ask themselves this question as well, because their willingness to accept risk and their values are probably different from mine. This exercise has carried me through the pandemic with little guilt and minimal fear of COVID.

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The Centers for Disease Control and Prevention says that vaccinated people can gather unmasked with certain individuals, skip the quarantine after exposure, and travel safely. Yet many health officials advise caution, including masking of vaccinated people in many settings and avoidance of travel. National guidance doesn’t address what is perhaps the most important factor in deciding what activities to participate in during a pandemic: personal risk tolerance.

We must consider the risk we pose to others and the risk others pose to us. The CDC has decreed that fully vaccinated individuals are not subject to quarantine after a known exposure. That fact alone is an endorsement of how effective the vaccines are at preventing transmission. The highest-risk close contact is one that occurs within a household. Studies show that if a person in your home has COVID-19 and you are not immune, your risk of acquiring the infection is between 10 and 20 percent. That means that after receiving both doses of either the Pfizer-BioNTech or Moderna vaccines, with approximately 90 percent efficacy, your risk of acquiring COVID-19 after exposure would be about 1 or 2 percent. Furthermore, research shows that those who do get infected after vaccination tend to have lower viral loads, which is thought to make infection less transmissible. Of course, none of these are absolutes. There is certainly residual risk when a person who is fully vaccinated and exposed to COVID-19 goes about their normal business.

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When I think about the risk to my family and me, I try to be realistic about vaccine efficacy. It is not 100 percent effective, but it’s close, and I want my life back. So I gather with vaccinated friends, and I also gather with unvaccinated friends in small groups. I have begun to travel for pleasure, including, recently, getting on a plane, but only to places with COVID-19 prevalence equivalent to or lower than what it is where I live. I dine indoors, but I would not go to a crowded nightclub until the case incidence drops much lower. Regardless of how protected I feel from the vaccine, I follow state regulations. For example, until the gathering limit changes, I would not have more than 10 people in my home, even if they were all vaccinated.

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The importance of the human connection should not be minimized either. The CDC says that fully vaccinated people can gather with unvaccinated people as long as none of those people are at increased risk for severe illness from COVID-19. Some of us have vaccine-hesitant elderly loved ones who are lonely and in need of human contact. When I ask myself if I could live with having made a decision to visit those people, I take their preferences and desires into account. The visit is safe for me and quite safe, though slightly less so, for them.

In the winter, with cases surging, my risk tolerance faced the ultimate test. My teenage son wanted to play high school basketball — an indoor, close-contact sport. I knew this was high-risk, yet the alternative was continued isolation and more time in front of a screen as the weather turned colder. I allowed him to play. He contracted COVID-19. I worried he would develop complications, and I held my breath waiting to see if anyone else in the household would fall ill, but I didn’t berate myself for the decision. And I still believe it was the right one.

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It is understandable that people are traumatized and scared after a year of death and devastation. Many are experiencing what has been termed fear of normal. It will take some people longer than others to feel comfortable enough to participate in activities previously deemed risky. But in truth, the COVID-19 vaccines are nothing short of a scientific miracle. And soon, every American adult will have had the option to be vaccinated. What you do with your immunity is largely up to you. But if you ask yourself the personal risk tolerance question, I hope you will be at peace with whatever decision you ultimately make.

Dr. Shira Doron serves as hospital epidemiologist and director of antimicrobial stewardship in the Division of Geographic Medicine and Infectious Diseases at Tufts Medical Center. She is also an associate professor of medicine at Tufts University School of Medicine.