Comment: How a vaxxed doctor judged his covid risk at a party

As mask mandates and case rates fall it’s a mental exercise that more of us will do each day.

By Robert M. Wachter / Special To The Washington Post

In the past few weeks, the tide of government coronavirus mandates has clearly turned. Pretty soon, nobody will be required to wear a mask in most indoor spaces. But that only shifts the decision onto the individual, so the question remains: Should you wear one?

If you’re wondering how to calculate risk in the post-mandate world, you may find it useful to see how I — a moderately cautious (and, I hope, relatively nondogmatic) academic physician who has written and spoken extensively about covid — concluded that jettisoning the mask last week at a friend’s 65th birthday party was safe or, at least, safe enough. You may not have as many statistics at the ready as I did, but many Americans may soon be doing some version of calculations like these several times a day.

Before I tell you about this one decision, here’s some context: I live in San Francisco: a blue city in a blue state, and one that’s been aggressive when it comes to coronavirus precautions. I’m 64; old enough to be at moderately high risk from the coronavirus. I’ve had three Pfizer shots and, to my knowledge, have never had covid.

Having made it this far without getting covid-19, I think it would be a dumb time for me to catch the virus. Case rates are falling fast enough that the risk will soon be sufficiently low for me to let down my guard. When? There’s no bright line separating safe from unsafe, but case rates of approximately 10 per 100,000 people per day and test positivity rates of less than 1 or 2 percent would make it quite unlikely that a person in line with me in the supermarket or sitting near me at a restaurant has covid. (No state has case rates quite that low, but Maryland is closest, at 12 cases per 100,000; its test-positivity rate is 2.9 percent.) When rates reach that level, I’ll begin eating indoors and will remove my mask in low-risk indoor settings. But I’ll still mask up in very crowded indoor spaces.

Why do I still fear a case of covid? First, after three shots, my chances of severe illness are low, but they’re not zero. Second, I worry about long covid; study results vary, but a reasonable interpretation is that about 5 percent of people who become infected after vaccination can expect symptoms that last longer than a month. And a recent study found a disconcerting rise in cardiovascular diagnoses, including heart attacks and strokes, in people previously infected with the coronavirus. Finally, while I don’t have much contact with young children, I do with immunosuppressed people and the elderly, and I don’t want to infect someone if I can avoid it.

When I was invited to my friend’s birthday party near Miami, though, I had little hesitation about saying yes: Many of my college pals would be there, and I’d get to stay with my recently widowed 86-year-old mother, who lives nearby. The host asked his guests to be vaccinated and boosted and to take a rapid test immediately beforehand. My assumption was that most did, raising the level of safety.

Case rates in Florida and in the hometowns of the guests were well above my maskless threshold (they averaged 30-80 cases per 100,000 residents per day), so I was not ready to eat and drink indoors there. Thankfully, the plan was that eating, drinking and socializing could be outside or in. That sounded great: I’d mask to pick up my food and drink inside, then make a beeline to the backyard.

Good plan, until nature intervened. Just as I pulled up to my friend’s house, it began to pour. I had three choices: leave the party; eat and drink outside: drenched, alone and pitiful; or ditch the mask and enjoy the party indoors.

Here was my quick calculation of the risks I’d be taking if I chose to join my friends inside. (Most of these odds are based on rigorous studies or official data, but some involved educated guesswork and extrapolation. But even if I was off by a significant amount in some estimates, it wouldn’t matter much for the crux of the decision.)

• Odds that someone at the party was infected: About 1 in 50. This was a back-of-the-envelope calculation that began with Florida’s test-positivity rate, 17 percent, which I adjusted downward because the guests were mostly asymptomatic vaccinated professionals from blue states who had undergone rapid tests that day.

• Based on the previous estimate, odds in a group of 40 people that at least one guest has covid: about 50-50.

• Assuming face-to-face chats with 15 people at the party, odds that I’d have a close exposure to an infected person: About 1 in 5. I didn’t worry about those on the other side of the room, particularly since I propped open two doors for ventilation.

• Odds of contracting the coronavirus from a close conversation with an infected person: About 1 in 10. This is a particularly hard piece of data to find, especially in the omicron era. My estimate draws on a study of the risk of one person in a household infecting another member.

• So, my chances of getting covid from attending this party: About 1 in 50.

• Odds of needing to be hospitalized if I got covid, given my age and vaccination status: About 1 in 200.

• Odds that I’d die if I got covid: About 1 in 1,400.

• Odds that I’d get long covid in some form if I developed covid-19: about 1 in 20.

• Finally, odds of infecting my elderly mom if I visited her while infected: About 1 in 3. Again, I drew on research on transmission within households.

To estimate probabilities for those other bad outcomes, beyond the 1-in-50 chance of getting infected, I multiplied fractions:

• Chance I’d be hospitalized for covid-19: 1 in 10,000.

• Risk of dying of covid-19: 1 in 70,000.

• Odds of developing long covid: 1 in 1,000.

• Danger of infecting my mom: 1 in 150.

In the practice of medicine, our lifeblood is calculating and applying benefits and risks. Those were the risks. The benefits were enjoying a party with close friends, many of whom I hadn’t seen for years. Before walking in, I asked myself how I’d feel if any of these bad things happened. The answer was “terrible,” of course, but, given the low odds, I wouldn’t feel that I’d made the wrong decision. And so I entered, removing my mask after the first few minutes.

I tell you this whole soggy dog story not because it’s unusual, but because it’s not: It’s the kind of scenario that tens of millions of people have been grappling with since March 2020. The difference is that now, as the rules are stripped away, the decisions become entirely personal.

It’s understandable why, faced with this much math and angst, many folks have decided that going maskless everywhere is less stressful and safe enough. I wouldn’t argue with fully vaccinated people who choose to discard their masks in indoor settings. Odds are they’ll do fine. As for me, I loved the party, kept the virus at bay — though one attendee got covid a few days later, possibly from the gathering — and felt good about my decision. The next day I went back to wearing masks indoors and avoiding indoor dining; a decision I feel equally good about, and one that I’ll rethink if and when cases fall some more.

Dr. Robert M. Wachter is a professor and chair of the department of medicine at the University of California, San Francisco.

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