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COVID-19's Potential Effects On Asymptomatic Patients


More than a hundred million people worldwide have tested positive for the coronavirus, and the vast majority of them have recovered from the initial onset of symptoms. Others wrestle with lingering effects of COVID-19, the so-called long-haulers. And then there are those who had no symptoms. Researchers think they made up between a quarter to a third of all infections - no symptoms, no long-term health effects, right? Maybe, but maybe not. Joining us now to discuss this is Dr. Eric Topol. He is the director of Scripps Research Translational Institute.


ERIC TOPOL: Thanks, Lulu. Good to be with you.

GARCIA-NAVARRO: What kinds of things are doctors seeing in some of these asymptomatic patients?

TOPOL: Well, as you highlighted, they represent a significant fraction, so they don't even know they've had COVID. But when they've been studied with, for example, CT scans of their lungs, about half have abnormalities that are consistent with COVID.

GARCIA-NAVARRO: I mean, how does that work? How do doctors know for sure that these lingering effects are from COVID and not from something else?

TOPOL: Right. Well, because there's been four of those series in - so it replicates. And the findings on the CAT scans of the lungs are really just the same as people who have symptoms - perhaps not as severe - but these classic so-called ground glass opacifications and consolidation. So these are things that, in healthy people, would not be expected to be present at all. And we've seen the same sort of things in the heart. It hasn't been studied as much, but people without symptoms also have abnormalities of their heart by magnetic resonance imaging.

GARCIA-NAVARRO: And just to be clear, in any of the studies that you've seen, did any of the asymptomatic people have actual effects that they could feel?

TOPOL: Not at all. No, this was silent. They had no idea. So when they got the results of their CAT scan of their lungs, they were so surprised because they felt perfectly well. And the same thing for the people who had heart inflammation - they had no idea.

GARCIA-NAVARRO: Extraordinary.

TOPOL: Yeah, it is.

GARCIA-NAVARRO: And unusual, I imagine, for illnesses to manifest like this.

TOPOL: Definitely. Well, you know, part of it, Lulu, is the fact that there's just so many people affected here. It may have occurred with other illnesses, but we just don't have that kind of huge denominator of people to learn from.

GARCIA-NAVARRO: Fascinating. I'm curious how many people it is believed in the U.S. could be in this other category of asymptomatic people with lingering effects.

TOPOL: Right. So this is important because we know that there's 25 or so million infections that are confirmed, but the people who've had these PCR tests are largely people with symptoms. So if you even take the one-third of those and you get to, you know, 8 or 9 million - but we also know from the CDC and all the other estimates that at least 80 to 90 million people have actually had COVID. And that takes into account this group of people without any symptoms. So it's a very large fraction. I mean, we're talking about perhaps 10 million Americans who haven't had symptoms, who have COVID. And some of them will experience later these symptoms that could be indexed to a COVID infection.

GARCIA-NAVARRO: And do you think there needs to be planning when it comes to these long-term impacts? - because it is capricious in how it affects people, some severely with months of recovery, some barely or not at all. But having a lot of potentially ill people could have wide-ranging effects.

TOPOL: That's right. I mean, when you - even if you think it's, you know, 1% or half of percent, because the denominator of people is so massive, this could have a substantial impact in terms of the toll of heart, lung and possibly other organs. I mean, we learned from the very large - the largest study of long COVID was from China, recently published. And 13% had kidney damage eight or nine months later. So these effects that are not discernible to the people who have infections, necessarily, can be there for a long duration.

GARCIA-NAVARRO: And what should individuals do? If you're someone who has tested positive but have had no symptoms, what do they need to sort of do in order to take care of their health?

TOPOL: Well, you know, not to fret about it because there's still so many unknowns here, Lulu. I think the point is we need to study it so that we can inform people at some point down the road what might be in store. But at this point, it's not worth having anxiety because most people, of course, without symptoms, when you think about how many there are, are going to do exceedingly well. We really need to study this to nail it down.

GARCIA-NAVARRO: Dr. Eric Topol, director of Scripps Research Translational Institute, thank you very much for joining us.

TOPOL: Thank you. Transcript provided by NPR, Copyright NPR.