STEVE INSKEEP, HOST:
You could think of this as the winter of respiratory viruses.
A MARTÍNEZ, HOST:
Yep. You name it, someone's caught it. RSV, flu, COVID - they're all spreading fast a season, and some people come down with all three at the same time. So what does that look like, and who's most at risk? A new study from the CDC is out today.
INSKEEP: NPR health correspondent Rob Stein is here. Rob, good morning.
ROB STEIN, BYLINE: Good morning, Steve.
INSKEEP: Just to be clear on the science here, can people be sick with more than one virus at the same time?
STEIN: Yes, it definitely can happen. There's plenty of evidence of people testing positive for, say, COVID and the flu or flu and RSV. I talked about this with Dr. Tina Tan, an infectious disease specialist at Northwestern University.
TINA TAN: Absolutely. You can catch more than one virus at the same time. We've had kids that have actually had three different viruses. Some of them come in with RSV. They've also had influenza and enterovirus. There've been other kids who have presented with COVID and influenza. And so you can get more than one virus at the same time.
STEIN: And, you know, Steve, especially this year, which is so unusual because so many viruses have been surging simultaneously. Now, you know, it's unclear just how often this happens because most of the testing for this sort of thing is done on hospitalized patients who probably aren't representative of the general public. But some studies have found co-infections in up to 20% of those patients.
INSKEEP: Wow. Are some people more vulnerable than others to this co-infection?
STEIN: Yes, yes, kids. Kids appear to be far more likely to get more than one bug on top of the other, especially very young kids. Here's Amanda Jamieson, who studies respiratory viruses at Brown University.
AMANDA JAMIESON: It could be just because they're constantly being exposed to respiratory infections, but it could also be that their immune systems just haven't built up the immunity that older people have.
STEIN: And, you know, whatever the reason, lots of studies have found that kids are much more likely to get these so-called co-infections than older people. That said, co-infections can occur at any age, you know, and especially older people and others with weaker immune systems.
INSKEEP: If you get more than one virus, does that make you sicker?
STEIN: You know, it doesn't always, but there is growing evidence that it can. In fact, a new CDC study out today finds that's the case. The study involving more than 4,000 hospitalized kids found those who had COVID plus another virus, such as, you know, a cold virus, were significantly more likely to require oxygen to help them breathe and to end up requiring intensive care. Here's Dr. Nickolas Agathis from the CDC, who led the study of what he calls codetections.
NICKOLAS AGATHIS: We found that children under 5 had about twice the odds of having severe illness when they had a codetection compared to when they just had SARS-CoV-2 infection. And the children under 2 who had RSV were twice as likely to have severe illness compared to children who just had COVID and not RSV also.
STEIN: Now, the reason for that isn't entirely clear either, but it could be because multiple infections cause more inflammation in the body and because different respiratory viruses damage the lungs in different ways.
INSKEEP: Oh, yeah. So what can people do about this?
STEIN: So here, I'm going to sound like a broken record and, you know, talk about all the things you've heard so much about over the last few years. Get vaccinated against both COVID and the flu. Wash your hands a lot. Wear a mask in crowded, poorly ventilated places, especially around sick people.
INSKEEP: Oh, sure. This is just a reminder that mask in a crowded place helps against any virus at all.
STEIN: Absolutely. Absolutely.
INSKEEP: OK. NPR health correspondent Rob Stein, thanks.
STEIN: Thanks for having me.
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