Never had the flu? Scientists may know why

Summary

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Short Wave — “Never had the flu? Scientists may know why”

Date: April 3, 2026
Hosts: Emily Kwong & Regina Barber
Guest: Juana Summers (Host, All Things Considered)
Length (content): ~00:16–10:25

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Episode Overview

This episode of Short Wave is a biweekly health science news roundup, where hosts Emily Kwong and Regina Barber, joined by Juana Summers, dive into three big topics: why some people never get the flu, how little vigorous exercise might go a long way, and the global impact of fortifying everyday foods. The conversation is lively, accessible, and packed with new science findings to make you rethink your daily routines.

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Key Discussion Points & Insights

1. Why Do Some People Never Get the Flu? (02:44–05:38)

• Introducing the Mystery
  The team discusses people who, despite frequent exposure, have never contracted the flu—like Juana Summers herself.
• The Science
  • Scientists identified higher levels of a protein called dermcidin in the nose and mouth of individuals who never get flu symptoms, even with no history of flu vaccination (03:17).
  • The study, published in PNAS, focused on 19 healthcare workers with high patient contact but no flu.
  • Fun fact: The first participant was one of the researchers’ moms, a retired nurse (03:54).
• What is Dermcidin?
  • Known previously from sweat as a guard against bacteria and fungus, dermcidin was not known as an antiviral before this research (04:32).
  • In these “flu-resistant” people, dermcidin levels were much higher in saliva and nasal passages.
• Why Does This Matter?
  • Potential for new methods to identify people at greater flu risk (via dermcidin measurement), and for new preventative treatments—think nasal sprays or eye drops (05:01–05:24).
  • Dermcidin also blocks measles, some cold viruses, and flu strains already resistant to antivirals (05:24–05:38).

Notable Quotes

• “I always tell her that she has a superpower.”
  — Emily Kwong on the researcher’s mom (03:59)
• “Scientists don’t know exactly why some people have different levels of dermcidin…”
  — Emily Kwong (05:01)

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2. How Much Vigorous Exercise Do You Actually Need? (05:38–08:18)

• The New Data
  • Just 15-20 minutes of vigorous exercise a week can significantly reduce risk of severe diseases—including heart and kidney disease, type 2 diabetes, and dementia (05:48).
  • Study of 96,000+ people in the UK found intensity mattered more than total weekly exercise time (05:58–07:04).
• What Counts as Vigorous?
  • Defined as exercising at 70–85% of your maximum heart rate (06:23–06:29).
  • Not just “workouts”: Running up stairs, heavy grocery lifting, short cycling bursts—all can count (06:41).
• Expert Takeaways
  • Surprise: Short bursts of intensity are more important than previously believed (07:00–07:07).
  • American Heart Association recommends 75 min/week vigorous—or 150 min moderate—but this new evidence hints even less may be enough (07:07–07:26).
  • Sports medicine expert Dr. Eli Friedman: Actual high-intensity periods in many workouts are brief, and any exercise is beneficial (07:49–08:16).

Notable Quotes

• “We were struck by how much more important intensity was than total volume.”
  — Emily Kwong, paraphrasing lead researcher Ming Cueshen (07:04–07:07)
• “During workouts… if you look at the collective time that people are actually engaged in that high intensity, it’s not a lot.”
  — Dr. Eli Friedman (07:49–07:56)
• “This study… shows pushing yourself a little, even for a few seconds, can go a long way.”
  — Regina Barber (08:16)

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3. Food Fortification: The Global Health Booster (08:26–10:11)

• What are Fortified Foods?
  • Commonplace foods with added vitamins/minerals: iodized salt, bread with folic acid, breakfast cereals with iron (08:34–08:54).
  • Billions lack these essential micronutrients worldwide.
• Magnitude of the Impact
  • Study in The Lancet Global Health analyzed food fortification programs in 185 countries (09:12).
  • Result: Prevents 7 billion “nutrient gaps” globally—meaning fewer people develop deficiencies.
  • Even more gaps could be closed with stricter manufacturer compliance and better fortification (09:37–09:51).
• Real-World Example
  • California and Alabama now require folic acid fortification in corn masa flour to reduce birth defects (09:51–10:07).

Notable Quotes

• “Based on the best available data, these programs prevent 7 billion nutrient gaps worldwide.”
  — Emily Kwong (09:12)
• “You probably had iodized salts in a salt shaker—that’s fortified with iodine.”
  — Emily Kwong (08:34)

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Memorable Moments

• The Superpower Mom: The first study participant in the flu resistance study was the scientist's own mother, a never-sick retired nurse (03:54).
• Instantly Adjusting Habits: Regina sprinted for 30 seconds after learning about the power of even brief vigorous exercise (08:20).
• Science-Driven Humor:
  • “The flu heard you.” — Regina Barber, to Juana, joking about tempting fate (03:08).
  • “So my big takeaway here is that I definitely need to eat more vegetables and tortillas, huh?” — Juana Summers (10:07).

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Important Timestamps

• 02:44 — Episode moves into health stories; intro to the “never get the flu” phenomenon.
• 03:17 — Scientists discover dermcidin’s role in flu resistance.
• 04:32 — Dermcidin’s known antibacterial role and its unexpected antiviral power.
• 05:22 — Potential for new flu preventatives: nasal sprays/eye drops.
• 05:48 — New study: small amounts of vigorous exercise make a difference.
• 06:23 — What qualifies as “vigorous” exercise.
• 07:00 — Lead researcher surprised by importance of intensity over duration.
• 07:49 — Athletic trainer reflects on real-world workouts.
• 08:26 — Defining food fortification and its reach.
• 09:12 — Key global impact figures from fortification programs.
• 09:51 — Concrete examples: folic acid in tortillas.
• 10:07 — Lively wrap-up on food, exercise, and healthy habits.

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Takeaways

• Flu Resistance may be partly driven by the protein dermcidin; understanding this could lead to new ways to prevent flu and even treat other viral infections.
• Minimum Effort, Big Result: Even brief bursts of vigorous exercise can be far more important for health than the total time spent working out.
• Food Fortification Works: Strategic, widespread addition of micronutrients in food staples prevents massive health issues worldwide—and could do even more with broader implementation.

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Listen and learn more science with a side of fun: Search “Short Wave” on your favorite podcast app!

Transcript

[Announcer]

This message comes from US Bank Simplify how you do business with business essentials. A powerful combination of no monthly maintenance fee, checking and card payment processing. Deposit products are offered by U.S. bank National association member FDIC.

[Emily Kwong]

You're listening to Short Wave from NPR. Hey, short waivers. Emily Kwong here with my co host Regina Barber.

[Regina Barber]

Hey, Em.

[Emily Kwong]

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

[Juana Summers]

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

[Regina Barber]

Aw, we are fun. Excellent.

[Emily Kwong]

Well, this episode is our bi weekly 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.

[Juana Summers]

Sounds like most often the journals.

[Emily Kwong]

Yeah, that's just true.

[Regina Barber]

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

[Juana Summers]

It is.

[Emily Kwong]

Yeah, it's true.

[Regina Barber]

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

[Juana Summers]

Knock on wood.

[Sponsor/Advertisement Voice]

Not yet.

[Regina Barber]

Me neither.

[Emily Kwong]

I got a vaccine, so no.

[Regina 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.

[Juana Summers]

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

[Emily Kwong]

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

[Juana Summers]

Interesting. And then I think we're gonna round it all out with a study on the effects of fortifying food. Right?

[Emily Kwong]

That is right. Yep. Food, flu and fitness today on the show, let's get healthy. You're listening to Short Wave, the science podcast from N.

[Sponsor/Advertisement Voice]

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[Emily Kwong]

have gathered us all to this fine studio in the depths of NPR to chat about some new interesting health studies. Okay, Juana, which one do you want to talk about first?

[Juana Summers]

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?

[Regina Barber]

That is really ridiculous.

[Juana Summers]

Crossing my fingers I might have just jinxed myself.

[Regina Barber]

Good for you.

[Emily Kwong]

The flu. Heard you.

[Regina Barber]

Message us next week.

[Juana Summers]

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

[Regina 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 this study was published in the journal pnas.

[Juana Summers]

How'd they find this out?

[Emily Kwong]

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.

[Regina Barber]

And guess who the first study participant was.

[Juana Summers]

Okay, I am not gonna get this right. Was it the Surgeon General? Nope, nope.

[Regina Barber]

It was one of the research's moms.

[Sponsor/Advertisement Voice]

I love that I always tell her

[Emily Kwong]

that she has a superpower.

[Regina Barber]

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

[Juana Summers]

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

[Emily Kwong]

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

[Regina 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 dermcidin in their saliva and nasal passageways.

[Juana Summers]

Okay, 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.

[Emily Kwong]

Yeah. Scientists don't know exactly why some people have different levels of dermicidin, but Mariam says that measuring the amount could help identify people who may be at risk for. 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 dermcidin as an antiviral and as a preventative treatment.

[Regina Barber]

Like in a nasal spray or something?

[Emily Kwong]

Yeah, nasal spray. Or even eye drops with dermicidin that could protect someone. The researchers also found that dermcidin 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.

[Juana Summers]

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 okay?

[Regina Barber]

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

[Emily 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, we're less likely to develop serious conditions such as heart and kidney disease, type 2 diabetes, and dementia.

[Juana Summers]

Okay, so I have questions for you guys, and the first one. Is this what actually counts as vigorous exercise?

[Emily Kwong]

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

[Juana Summers]

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

[Emily 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.

[Regina Barber]

I spoke to the lead researcher of the study, Ming Cueshen, 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.

[Juana Summers]

Hmm. And this was surprising to the scientists.

[Emily Kwong]

It was at least to Ming Shui. We are very surprised.

[Juana Summers]

We expected the higher intensity activity could

[Emily Kwong]

be beneficial, but we were struck by how much more important intensity was than total volume, 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.

[Juana Summers]

Interesting.

[Regina Barber]

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 these short bursts of intensity during that workout.

[Juana Summers]

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

[Regina Barber]

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

[Emily Kwong]

if you look at, like, the collective

[Announcer]

time that people are actually engaged in that high intensity, it's not a lot.

[Regina 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. And any exercise is good. And that this study, it shows pushing yourself a little, even for a few seconds, can go a long way.

[Juana Summers]

Okay, I'm gonna keep that in the back of my head when I go to the gym.

[Emily Kwong]

Yeah, let's go sprint after this, up some stairs.

[Regina Barber]

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

[Juana Summers]

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.

[Regina Barber]

Yeah, it.

[Emily Kwong]

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.

[Juana Summers]

You're thinking of something like Wheaties.

[Emily Kwong]

Yes, I am.

[Regina Barber]

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

[Emily Kwong]

Yum.

[Regina 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

[Juana Summers]

serious health consequences, from susceptibility to disease

[Emily Kwong]

to impaired growth and development for young children, especially 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 7 billion nutrient gaps worldwide. So this is basically evidence that these programs do have a massive impact.

[Regina 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.

[Emily 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 masa flour, which is used to make tortillas. Yeah. Alabama will follow suit with a similar law in June.

[Juana Summers]

So my big takeaway here is that I definitely need to eat more vegetables and tortillas. Huh?

[Regina Barber]

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

[Juana Summers]

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

[Regina Barber]

Okay.

[Emily Kwong]

Ready, set, go. Okay. No. Before you run off, Gina, Juana, thank you for hanging out and talking about all things personal health with me today.

[Juana Summers]

Let's do it again soon.

[Regina Barber]

Yeah.

[Emily Kwong]

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.

[Regina Barber]

And if you love Juana as much as we do, Aww. Check out our work on consider this NPR's afternoon podcast about what the news means for you.

[Emily Kwong]

It's really good. Go ahead.

[Regina Barber]

This episode was produced by Jordan Marie Smith and Burleigh McCoy. It was edited by our showrunner Rebecca Ramirez and Patrick Jaron Watananan.

[Emily Kwong]

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

[Regina Barber]

And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from N. Let's get physical, physical.

[Emily Kwong]

Dun dun, dun dun.

[Regina Barber]

Get physical.

[Emily Kwong]

Do you know Gina used to be in a band?

[Juana Summers]

I did not.

[Emily Kwong]

Yeah, she was in a punk band.

[Regina Barber]

I got in a punk band. You were in a grunge band?

[Emily Kwong]

Okay. I don't.

[Juana Summers]

Are you still in a grunge band?

[Regina Barber]

I don't know the difference. No.

[Emily Kwong]

I was in high school because I was born. I never saw the 80s.

[Regina Barber]

I mean, grunge was in the 90s, but it's cool.

[Sponsor/Advertisement Voice]

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