Never had the flu? Scientists may know why

Scientists estimate somewhere between 5%-35% of people do not get sick from the flu despite being exposed to the virus that causes it. Now, researchers may have figured out why. The team looked at mouthwash samples from 19 healthcare workers who, despite frequent contact with infected patients, report never getting flu symptoms. Today on Short Wave, we talk about how what they found could help scientists develop treatments and strategies to protect people who do get the flu. If you liked this episode, check out our show on an effort to map the entire immune system https://lnk.to/lyKF9y. Interested in more health science? Email us your question at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave http://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:16Regina Barber?

  You're listening to Short Wave from NPR.

• 0:20Emily Kwong?

  Hey, Short Wavers. Emily Kwong here with my co-host, Regina Barber.

• 0:24Speaker 03

  Hey, Em.

• 0:24Emily Kwong?

  Hi, and Juana Summers, one of the many awesome hosts of All Things Considered. Aren't you so excited to take a break from the hard news?

• 0:30Speaker 03

  It's always fun hanging out with y'all.

• 0:32Emily Kwong?

  Oh, we are fun.

• 0:33Speaker 03

  Excellent.

• 0:34Emily Kwong?

  Well, this episode is our biweekly Science News Roundup, where we wax poetic about some of the most interesting science stories we found online, in the journals, in pop culture, anywhere cool science could be happening.

• 0:45Speaker 03

  Sounds like most often the journals.

• 0:46Emily Kwong?

  Yeah, it's just true.

• 0:47Regina Barber?

  Science is happening around us all the time. But this week, the stories we found are mostly focused on health. See, like, that is around us, right?

• 0:56Speaker 03

  It is, yeah.

• 0:56Emily Kwong?

  It's true.

• 0:57Regina Barber?

  Have either of you gotten the flu this season? This is my important question for our show.

• 1:01Speaker 03

  Knock on wood, not yet.

• 1:02Regina Barber?

  Me neither.

• 1:03Emily Kwong?

  I got a vaccine, so no.

• 1:04Regina Barber?

  Yeah, awesome, awesome. Well, I'll be curious to see, like, what you think about this first topic, because we are talking about people who have never gotten the flu. And then we're going to talk about something that I think Juana is going to be interested in: exercise.

• 1:19Speaker 03

  Oh, yeah, I'm a runner. I'm excited for this.

• 1:22Emily Kwong?

  Our second story also may change up your routine because it's about why you may need less vigorous exercise than you think.

• 1:28Speaker 03

  Interesting. And then I think we're going to round it all out with a study on the effects of fortifying food, right?

• 1:33Emily Kwong?

  That is right.

• 1:33Speaker 03

  Yep.

• 1:34Emily Kwong?

  Food, flu, and fitness today on the show. Let's get healthy. You're listening to Short Wave, the science podcast from NPR.

• 1:48Speaker 04

  Stay tuned for the following announcements and messages from our sponsors.

• 1:53Speaker 05

  This week on the NPR Politics Podcast, the midterm elections are wrapping up and millions of people have already voted. We're taking one final check of the electoral pulse with a new NPR PBS News Marist Poll. It shows Democrats still poised to make gains, but also with some warning signs for just how many. We'll explain on the NPR Politics Podcast.

• 2:16Speaker 06

  Oh, Kevin, it feels good to be back. It sure does, Casey. And what a time. The world is talking about AI and what's going on in Silicon Valley. And we are here with a new show to tell you all about it. That's right, Kevin. On our new show, Machine Gods, twice a week, we'll be bringing you the biggest news in tech and bring you unmatched access to the real titans of this industry. You can find Machine Gods from NPR on the NPR app or wherever you get your podcasts.

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• 2:55Emily Kwong?

  Okay, Gina and Wana, I have gathered us all to this fine studio in the depths of NPR to chat about some new, interesting health studies.

• 3:04Speaker 03

  Okay.

• 3:04Emily Kwong?

  Wana, which one do you want to talk about first?

• 3:07Speaker 03

  Okay, I want to start off with this flu story because I am not a person who really gets the flu. I don't think I've actually ever had it before. What about you guys?

• 3:15Regina Barber?

  That is ridiculous.

• 3:17Speaker 03

  Crossing my fingers. I might have disjinxed myself.

• 3:19Regina Barber?

  Good for you.

• 3:21Speaker 03

  The flu heard you.

• 3:22Regina Barber?

  Message us next week.

• 3:23Speaker 03

  So it sounds like this story is kind of about people like me who don't get the flu. And so scientists seem to have a clue now as to why?

• 3:30Regina Barber?

  Yeah, so scientists found a lot of this one small protein in the noses and mouths of people who reported never getting flu symptoms. And that seems likely to protect them from the flu virus. And the study was published in the journal PNAS.

• 3:43Speaker 03

  How'd they find this out?

• 3:44Regina Barber?

  Yeah, scientists found a special group of participants for this study, 19 healthcare workers. So 19 people who had a ton of close contact with sick patients, but never once had flu-like symptoms themselves. These folks also had never had a flu vaccine in their lives.

• 3:59Speaker 03

  And guess who the first study participant was? Okay, I am not going to get this right. Was it the Surgeon General?

• 4:06Regina Barber?

  Nope, nope. It was one of the researcher's moms.

• 4:09Speaker 03

  I love that.

• 4:10Regina Barber?

  I always tell her that she has a superpower.

• 4:15Regina Barber?

  Mariam Ferrer Garcia is a virologist who worked on the study. She's based at the Fasabio Foundation in Spain. And she always wondered why her mom, who's this retired nurse, managed to never get the flu. So Mariam and her team collected mouthwash samples from healthy healthcare workers in search of a reason. And they found high levels of this protein called dermcyden. It seems to block the flu virus before it even gets into cells. But this is not what dermcyden was known for.

• 4:42Speaker 03

  OK, hold up for a second. Scientists already knew that some people had this protein?

• 4:45Emily Kwong?

  Yes. Dermcyden is found in human sweat, where it blocks bacteria and fungus from infecting our skin. But what scientists didn't know is that dermcyden is an antiviral, too.

• 4:55Regina Barber?

  Yeah, so compared to healthy people who have definitely had the flu before, to these like flu-resistant healthcare workers, they had a much higher level of dermcyden in their saliva and nasal passageways.

• 5:07Speaker 03

  OK, let me see if I understand this. So the amount of this protein is ramped up in some people even before a person is exposed to the flu?

• 5:14Emily Kwong?

  Yeah, scientists don't know exactly why some people have different levels of dermcyden. But Mariam says that measuring the amount could help identify people who may be at risk for getting very sick from the flu. And then making sure those folks get a flu vaccine for sure. Scientists also want to explore how to use dermcyden as an antiviral and as a preventative treatment.

• 5:35Regina Barber?

  Like in a nasal spray or something?

• 5:37Emily Kwong?

  Yeah, nasal spray or even eye drops with dermcyden that could protect someone.

• 5:41Speaker 03

  Ooh.

• 5:41Emily Kwong?

  The researchers also found that dermcyden blocked measles, one of the viruses that causes the common cold, and multiple strains of the flu, including a strain that's already resistant to current antivirals.

• 5:51Speaker 03

  Interesting. All right, let's move on to topic two, which is about vigorous exercise. You guys both know that I'm a runner, but sometimes it's more of a jog than a sprint. Is that OK?

• 6:01Regina Barber?

  Yeah, almost only jog. But, Moana, if you're getting at least 15 to 20 minutes of this vigorous exercise a week, then yeah, you're doing great.

• 6:11Emily Kwong?

  Yeah, researchers discovered this by looking at survey data showing the exercise habits of over 96,000 people in the UK. And they found that people who put in just a few minutes of vigorous exercise a day were less likely to develop serious conditions, such as heart and kidney disease, type 2 diabetes, and dementia.

• 6:30Speaker 03

  OK, so I have questions for you guys. And the first one is this. What actually counts as vigorous exercise?

• 6:35Regina Barber?

  Yeah.

• 6:36Emily Kwong?

  It's a really good question, yeah. So, do you have a heart rate monitor?

• 6:39Speaker 03

  I do. I've got a little heart rate on my wrist.

• 6:42Emily Kwong?

  Well, it depends on your age, but generally speaking, the American Heart Association defines vigorous exercise as your body reaching 70 to 85% of your max heart rate. It's different for different ages and health levels.

• 6:54Regina Barber?

  I spoke to the lead researcher of this study, Ming Chui Shen, and he said that even small things could count as vigorous exercise, like going up the stairs quickly or carrying heavy groceries or short bursts of cycling or running, which is really a good reminder for people who can't do like a ton of cardio.

• 7:11Emily Kwong?

  Hmm. And this was surprising to the scientists? It was at least to Ming Chui.

• 7:15Speaker 08

  We are very surprised. We expected the higher intensity activity could be beneficial, but we were struck by how much more important intensity was than total volume.

• 7:29Emily Kwong?

  Because the American Heart Association suggests 75 minutes of vigorous exercise a week. And then along comes this study saying, maybe you don't need that much.

• 7:38Regina Barber?

  Interesting. And it's also worth noting that the American Heart Association says that you can alternatively do 150 minutes of moderate exercise. But this study suggests it's best to prioritize the short bursts of intensity during that workout.

• 7:51Emily Kwong?

  Interesting. What do people in the sports world, though, have to say about all of this?

• 7:55Regina Barber?

  Yes, so that's what I thought, too. And one expert I talked to wasn't that surprised. In fact, he says that during workouts.

• 8:02Speaker 09

  If you look at like the collective time that people are actually engaged in that high intensity, it's not a lot.

• 8:08Regina Barber?

  This is Dr. Eli Friedman from Cedars-Sinai in Los Angeles. He trains athletes. So he wasn't surprised, but he also wanted to caution that even though vigorous exercise is important, he doesn't want people to be discouraged from doing less intense exercise. Any exercise is good. And that this study, it shows pushing yourself a little, even for a few seconds, can go a long way.

• 8:29Emily Kwong?

  OK, I'm gonna keep that in the back of my head when I go to the gym tomorrow. Yeah, let's go sprint after this, up some stairs.

• 8:33Regina Barber?

  I literally sprinted for like 30 seconds after I did this story.

• 8:39Emily Kwong?

  Okay, and do we all feel ready to move on to the final topic? I think it's food fortification. I do not know what that is. Please help. Yeah. It is so technical sounding, but fortified foods are pretty common. You've probably had iodized salts in a salt shaker. That's fortified with iodine. There's bread fortified with folic acid and breakfast cereal fortified with iron. You're thinking of something like Wheaties? Yes, I am.

• 9:03Regina Barber?

  Yeah, I just ate fortified cereal this morning. It was like cinnamon checks.

• 9:07Emily Kwong?

  Yum.

• 9:07Regina Barber?

  And basically fortified foods contain carefully calculated boosts of essential vitamins and minerals because billions of people around the world are not getting enough micronutrients. And over time, a micronutrient deficiency has serious health consequences.

• 9:22Speaker 10

  From susceptibility to disease to impaired growth and development for young children, especially.

• 9:29Emily Kwong?

  Mduzi Mboya is the co-author of a new study in the Lancet Global Health, which measured the impact of large-scale food fortification programs in 185 countries. And his team found that based on the best available data, these programs prevent seven billion nutrient gaps worldwide. So this is basically evidence that these programs do have a massive impact.

• 9:50Regina Barber?

  And they estimate that even more nutrient gaps could be prevented if food fortification programs had higher compliance. This involves manufacturers consistently fortifying staple foods at the levels required by national standards.

• 10:04Emily Kwong?

  As an example, a nutrient gap in folic acid has been linked to neural tube defects in infants. And that's why California now requires manufacturers to add folic acid to corn moss of flour, which is used to make tortillas. Yeah, Alabama will follow suit with a similar law in June. So my big takeaway here is that I definitely need to eat more vegetables than tortillas, huh?

• 10:24Regina Barber?

  But you also need to like sprint just a baby, baby amount.

• 10:27Emily Kwong?

  Just a little bit. I'll sprint out of the studio soon.

• 10:29Regina Barber?

  Yeah.

• 10:30Emily Kwong?

  Ready, set, go. Okay, no, before you run off, Gina Wana, thank you for hanging out and talking about all things personal health with me today. Let's do it again soon. Yeah. For more science stories just like these, follow Short Wave on whatever app you're listening to. It helps you never miss a new episode.

• 10:45Regina Barber?

  And if you love Wana as much as we do,

• 10:47Emily Kwong?

  Aww.

• 10:48Regina Barber?

  check out our work on Consider This, NPR's afternoon podcast about what the news means for you.

• 10:53Emily Kwong?

  It's really good.

• 10:55Regina Barber?

  Go ahead. This episode was produced by Jordan Marie Smith and Burley McCoy. It was edited by our showrunner Rebecca Ramirez and Patrick Jaren Watanen.

• 11:03Emily Kwong?

  Tyler Jones checked the facts, and Hannah Glovna and Robert Rodriguez were the audio engineers. I'm Emily Kwong.

• 11:09Regina Barber?

  And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from NPR.

• 11:18Emily Kwong?

  Let's get physical. Physical. Dun, dun, dun, dun, dun. I wanna get physical. Do you know Gina used to be in a band?

• 11:24Regina Barber?

  I did not.

• 11:25Emily Kwong?

  Yeah, she was in a punk band.

• 11:27Regina Barber?

  Ooh.

• 11:27Emily Kwong?

  I was not in a punk band. I was in a grunge band. Okay, I don't even know the difference. No, I was in high school. Because I was born, I never saw the 80s. I mean, grunge was in the 90s, but it's cool.

• 11:36Speaker 00

  Stay tuned for the following announcements and messages from our sponsors.

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  The 2026 midterm elections are upon us. On November 3rd, voters will determine what the next two years of their local leadership and the balance of national government will look like. Listen to the NPR News Now podcast for all the updates you need ahead of and after November 3rd from NPR News.

• 12:03Speaker 11

  American journalist Austin Teice vanished in Syria over a decade ago. For years, we've been searching for him, and now we finally have some answers.

• 12:15Speaker 07

  This is the prison that Austin was in.

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  Oh, my God. We found Austin's file.

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  Listen to Where Is Austin Teice from NPR's Embedded and BBC Radio 4, on the NPR app or wherever you get your podcasts.