Interview: A UCSF doctor calculates the risk of not masking up in public transit

This week has seen a major shift in where and when masks must be worn to reduce COVID-19 spread, following a court ruling out of Florida.

In its wake, airlines, airports and many public transit systems have announced they’ll no longer require passengers to mask up. That includes the Sacramento International Airport and SacRT.

This might have you wondering about navigating public spaces in the coming weeks and months, especially if you’re traveling.

UC San Francisco Professor and Chair of the Department of Medicine Dr. Robert Wachter discussed his risk calculations with CapRadio’s Randol White.

Can I get your thoughts on this ruling and how it's upended mask guidelines? Are you concerned about any ramifications? 

Well, I'm super concerned about the ruling because I just don't believe that decisions about public health should be made by a judge as opposed to an agency filled with experts on public health. And I think if the ruling stands, that's really problematic if the CDC or other appropriate federal agencies can't institute a mandate in the face of a rapidly changing pandemic threat, I think that puts us in a really bad place. 

The decision in general, you know, the CDC was probably gearing up to make the same decision in a week or two, although cases are going up moderately quickly. I think it would have been a pretty tricky call. But in general, I think we have reached a point of the pandemic where it's reasonable to think twice about mandates because individual people have so many tools to keep themselves safe.

Doctor, if you're still wanting to wear a mask in public settings, N95 or KN95 are still the gold standard, correct? 

Yeah, that's correct. They work substantially better than anything else. A surgical mask works reasonably well, and a cloth mask does next to nothing. 

If you're the only one with an N95 on, how effective might it be?

Pretty effective. I mean, the reason I know that is I and my colleagues take care of people we know have COVID. I mean, they come to the hospital, they have a diagnosis of COVID. And what do we do? We wear N95 when we take care of them, and it's actually quite unusual to see a health care worker get infected from an infected patient. 

Let's walk through some calculations you might consider when deciding whether to fly without a mask. Where do you start? 

Well, let me start from the end. At this point, there is enough virus in the environment. The case rates are high enough and as you know, they're significant underestimates now of the true number of cases because of home testing. But even [accounting] for that, they are high-ish. They're going up. The test positivity rates are going up, the wastewater is going up in some regions. Luckily, hospitalizations are not. 

But I calculated the other day in San Francisco — which is not particularly being hit hard by COVID — on a plane with 150 people, the chances that somebody on the plane has COVID is nearly 100%. To me, it's not even that close a call. And I think part of the reason is that I always ask myself, if I get COVID from this thing, would it have been worth it? And the answer is going out to dinner with good friends and taking my mask off to do that, I would have said, you know, I'm happy I got it. But you know, I did it because I wanted to, and the only way to eat dinner is take your mask up. Getting it sitting on an airplane for a few hours, I wouldn't feel like it's worth it.

I don't wear a mask everywhere indoors. I'm comfortable having people over to the house. I'm comfortable playing poker with seven vaccinated buddies. So you know, those are things I am comfortable doing. But in pretty much every form of public transportation, I would wear a mask. When would I not in an airplane? If I looked around and there was nobody within three or four rows of me, I probably would take it off.