How a single flu shot could protect you for decades

Summary

Short Wave Episode Summary

Episode Title: How a Single Flu Shot Could Protect You for Decades
Date: June 10, 2026
Host: Regina Barber (NPR)
Guest: Adolfo Garcia Sastre, Viral Immunologist at Icahn School of Medicine, Mount Sinai

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Main Theme

This episode dives into the science and promise of the “universal flu vaccine”—a single shot designed to protect against all types of influenza viruses for years, eliminating the need for annual flu vaccinations. Host Regina Barber interviews Dr. Adolfo Garcia Sastre, whose team recently completed a phase one trial of such a vaccine. The conversation explores why yearly flu shots are currently necessary, the immunology breakthroughs enabling a universal vaccine, and the hurdles (both scientific and financial) that remain.

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Key Discussion Points and Insights

1. Why We Need a Yearly Flu Vaccine

• Constant Mutation: Influenza viruses mutate and evolve every year, forcing annual vaccine updates.
  • “That’s because the virus changes every year.” — Adolfo Garcia Sastre [03:59]
• Three Main Circulating Strains: Current vaccines have three components to cover Influenza A (subtypes H1 and H3) and Influenza B.
  • “We are talking about three viruses right now…influenza A and influenza B. A comes also in two shapes right now in humans that are called H1 and H3.” — Adolfo Garcia Sastre [04:07]
• Surveillance and Mismatches: Vaccine composition is based on predictions, which sometimes miss new dominant strains, reducing effectiveness.
  • “Sometimes we miss it for at least one of the components... Instead of perhaps an efficacy of 70% prevention from disease, then it goes down to 30% because it’s mismatched.” — Adolfo Garcia Sastre [05:36]

2. The Universal Flu Vaccine Approach

• Targeting Conserved Regions: Universal vaccines aim at parts of the virus that don’t change much—so-called “conserved areas.”

  • “What you’re working on is targeting regions that stay the same in the influenza virus... to make this universal flu vaccine, one that we wouldn’t need to get every year.” — Regina Barber [05:57]
  • “Not every conserved area is able to induce an immune response that will be able to protect... You need to identify these ones that are able to protect.” — Adolfo Garcia Sastre [06:42]

• A Memorable Analogy:

  • Dr. Garcia Sastre likens the process to figuring out which parts of a cow (representing the virus) could be protected to prevent harm:
  • “Imagine that flu is a cow... You want to get protection from a cow. You need to target areas... that will prevent damage to you.” [07:03]

• Design Challenge:

  • Existing vaccines primarily induce immune responses to variable (changing) regions.
  • The breakthrough is in finding and prompting immunity to the conserved, protective parts of the virus.
  • “We need to induce an immune response against these conserved areas by designing a vaccine that is different from the ones that we have, because the ones that we have all induce good responses against the variable areas.” — Adolfo Garcia Sastre [07:51]

3. Progress and Scientific Hurdles

• Early Success:
  • Dr. Garcia Sastre’s team has completed phase one clinical trials.
  • “Phase one, the main thing that tells you is safety. And the second thing they tell you [is] whether you get the immune response that you think is good for the vaccine.” — Adolfo Garcia Sastre [08:38]
  • “In the phase one, we got induction of antibodies at levels that we think they will be protective.” [08:50]
• Next Steps:
  • Need to test in larger, longer phase two studies to prove true effectiveness and duration of protection.
  • “We have not started phase two.” — Adolfo Garcia Sastre [09:06]

4. Barriers: Funding and Resource Gaps

• Money, Not Science, is the Primary Obstacle:
  • “What's holding up phase two?... Mainly money.” [09:11]
  • Past NIH programs have stalled or ended, leaving the research unfunded and clinical materials at risk.
  • “If they are not going, they need to maintain a stability program. And this costs money, money that we don’t have.” — Adolfo Garcia Sastre [10:17]
• Emotional Toll:
  • “How does that feel, that you could make something that could help so many people, but it gets stopped by money?” — Regina Barber [10:45]
  • “Well, it's frustrating, right?... It's not trivial and we are not able to put this material that we have right now into humans. Then, it will be lost.” — Adolfo Garcia Sastre [10:52]

5. Future Outlook and Hopefulness

• Practical Challenges:

  • It takes years to prove long-term vaccine effectiveness; at least four years of monitoring required.
    • “We want to prove not only that it prevents flu the year that we give the vaccine, but also prevents flu the second year, the third year and the fourth year. Right. So just to prove that we have a vaccine that protects for four years requires four years of follow up.” — Adolfo Garcia Sastre [11:35]

• Scientific Spirit:

  • Despite setbacks, Garcia Sastre remains driven by discovery and hope:
  • “I am [optimistic]. If not, I will not be working on it. But who knows, I also try not to become depressive at the end. This doesn't, doesn't move forward. Right. At least... the discovery process... is very exciting. Whether we can translate it for the good of humanity, even better.” — Adolfo Garcia Sastre [12:06]

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Notable Quotes & Memorable Moments

• On Hitting Funding Walls:
  • “It’s frustrating, right?... It’s not trivial and we are not able to put this material... into humans. Then it will be lost.” — Adolfo Garcia Sastre [10:52]
• What a Universal Vaccine Means:
  • “This shot that we are working on will protect not only against seasonal influenza... but also will prevent pandemic influenza from an animal reservoir.” — Adolfo Garcia Sastre [01:12]
• Why Pursue This Research:
  • “To me, the discovery process... is very exciting. Also, whether we can translate it for the good of humanity, even better.” — Adolfo Garcia Sastre [12:10]

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Important Timestamps

| Time | Segment | |---------|----------------------------------------------| | 00:48 | Introducing the universal flu vaccine concept | | 03:53 | Why annual flu vaccines are needed | | 05:57 | Targeting “conserved regions” for a universal solution | | 07:03 | “Cow” analogy illustrating the vaccine design challenge | | 08:38 | Phase one trial results and significance | | 09:11 | Discussion of funding challenges | | 11:35 | Discussing the required proof and timelines | | 12:06 | Garcia Sastre’s motivation and outlook |

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Tone and Style

The conversation maintains Short Wave’s trademark blend of accessibility, science literacy, and lightheartedness—even as it addresses the sobering reality of stalled medical progress due to funding gaps. Dr. Garcia Sastre is passionate and candid, and the host skillfully guides the discussion with curiosity and empathy.

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Summary Takeaway

A universal flu vaccine is scientifically possible and within reach, but progressing from promising trials to real-world impact will require major investments and patience. The work is ongoing, and the scientific community remains cautiously optimistic—even as financial obstacles loom largest.

Transcript

[A]

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[B]

You're listening to Short Wave from NPR. The Centers for Disease Control and Prevention estimates that anywhere from 24,000 to to 81,000 people died from the flu during this past flu season. Hundreds of thousands more were hospitalized and millions were infected. And this is a moderate season. In the event of a whole flu pandemic, those numbers could be much higher.

[C]

There is more than 100 potential pandemic flu viruses that could start the pandemic.

[B]

That's Adolfo Garcia Sastre, a viral immunologist at the Icahn School of Medicine at Mount Sinai in New York. He's working on a vaccine that could not only protect people from a pandemic flu virus, but all flu viruses. No more annual flu shots. He calls it a universal flu vaccine.

[C]

This shot that we are working on will protect not only against seasonal influenza, not only of this year, not only against next year and next year and next year and this year, but also we'll prevent pandemic influenza from an animal reservoir.

[B]

A vaccine like this hasn't been possible before because the virus that causes the flu, influenza, mutates every year, evading the previous year's vaccine.

[C]

But he says the virus cannot change completely. If not, we will not recognize it as influenza.

[B]

And Adolfo and his team are working on a vaccine that can target all versions of the influenza virus, past, present and future. If they can find the resources

[C]

today

[B]

on the show, the science behind a vaccine against all flus and what scientists need to make it a reality. I'm Regina Barber, and you're listening to Shortwave, the science podcast from npr.

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[B]

okay, Adolfo, what about the flu virus impacts? Why we need a yearly vaccine?

[C]

Yeah, so that's because the virus changes every year. And when we are talking about human influenza, we're talking about three viruses right now, okay? And that's the reason why the vaccine has three components. So there is what they are called the influenza A and influenza B. A comes also in two shapes right now in humans that are called H1 and H3. And H refers to one of the proteins of the virus, the spike of the virus that is called hemagglutinin and that's H1 will be hemagglutinin subtype 1, H3 will be hemagglutin in subtype 3. All these three viruses are circulating in people. Some seasons they are mainly H3s, some seasons they are mainly H1s. Some seasons they are mainly B. But there is always H1s, H3 and Bs causing infections in humans.

[B]

So flu A, which comes in two H subtypes and then Bs.

[C]

Okay, so we need three components, right? But each one of these viruses change every year and they do so to avoid preexisting immunity. And the vaccine tries to cover the strains that are circulating. So we make the vaccine for whatever is gonna be circulating this year. And the prediction come from the surveillance that is being done for influenza to see what is circulating at any time in the year. And sometimes we miss it for at least one of the components. This year, for example, we miss it for H3S. There was this new strain that became quickly very, very prevalent and this one was not very well covered by the H3 component of the vaccine. Still, it Provides you some efficacy, but instead of perhaps an efficacy of 70% prevention from disease, then it goes down to 30% because it's mismatched.

[B]

Right. So all of this refers to current vaccine strategies, like what we do now. That's based on targeting parts of the viruses that change. But what you're working on is targeting regions that stay the same in the influenza virus in order to make this universal flu vaccine, one that we wouldn't need to get every year. Now, historically, there have been barriers to creating this kind of vaccine. What are they?

[C]

So there are two types of barriers, the scientific barriers. And the other thing is more about what type of resources you need to put, which is more of an economical reason than a scientific reason. The scientific reason is because influenza has

[B]

conserved areas, the parts of the influenza virus that doesn't change.

[C]

They don't change that. Correct. That's what I mean by conserve. But not every conserve area is able to induce an immune response that will be able to protect. So you need to identify these ones that are able to protect. It's like just imagine that flu is a cow.

[B]

It's a cow.

[C]

So let's imagine it's a cow already there. So you want to get protection from a cow. You need to target areas in the cow that will prevent damage to you. Right. So perhaps you need to stop or cover the head with foam, let's say that. Right. And then the cow cannot do damage. Or the feet, then. Even if they kick you, it cannot do damage. But if you cover the tail well, the cow cannot give you any damage with the tail.

[B]

Right.

[C]

So there are some areas in the virus that we called non protective. So we need to find the protective areas of the virus that are conserved and protective. Yeah.

[B]

Okay.

[C]

And then we need to induce an immune response against these conserved areas by designing a vaccine that is different from the ones that we have, because the ones that we have all induce good responses against the variable areas.

[B]

Variable areas? The parts of the virus that change.

[C]

Yeah. Which are very good. But they don't protect you against future strains. They don't protect you against pandemic strains.

[B]

The science hasn't gotten here yet because we haven't been able to find those regions or.

[C]

Well, it took a while. It took a while. Now we have some candidates.

[B]

Okay, we have candidates. And then we have to make a vaccine that will react to these regions that don't change.

[C]

Yeah. Correct.

[B]

Okay, so your lab is working on a universal flu vaccine, and you just finished phase one trial. What did phase one tell you?

[C]

So phase one the main thing that tells you is safety. And the second thing they tell you whether you get the immune response that you think is good for the vaccine.

[B]

Yeah. Did you?

[C]

Yeah.

[B]

Wow.

[C]

In the phase one, we got induction of antibodies at levels that we think they will be protective. We have not been able to prove that in humans, but we think that the levels that we achieve, they will be protective.

[B]

So have you started phase two?

[C]

Phase two, we have not started. We have been in phase one.

[B]

What's holding up phase two?

[C]

Mainly money. They are very costly. And there was a NIH program that was called Civic that was for trying to get improved influenza vaccines. We were part of this program, but this program has been stopped and right now it's unclear whether it's going to restart.

[B]

Was this part of the recent government cuts that happened in the last year?

[C]

Well, was not really a cut, but there has been also a lot of slowdown in finances from nih. So these contracts, they were supposed to at one moment bring clinical trials, but because funding stopped it and there is no call for new proposals yet. And if a call comes, because it takes time to review and then get funded, there's going to be at least a gap of one year or two years.

[B]

So what will happen to all your material, all those vaccines in that time?

[C]

The problem with the vaccines that we are ready to go is that if they are not going, they need to maintain a stability program. And this costs money, money that we don't have. So we are trying to find partners outside NIH to finance for at least a stability program, or if not also for some phase 2, phase 1 clinical trials that we still need to do.

[B]

How does that feel, that you could make something that could help so many people, but it gets stopped by money?

[C]

Well, it's frustrating, right? I think the money is there, but. But it's impossible to manage the program on time to be able to renew it again because of the amount of changes that have been in nih. It's also the amount of money that has been put into this program already. It's not trivial and we are not able to put this material that we have right now into humans. Then it will be lost. And we want to in the future to. We need to start again making this material.

[B]

Are you optimistic that there will be this universal flu vaccine like created in your lifetime?

[C]

In my lifetime, I hope so. But in the next five years, I think it's a big challenge because we want to prove not only that it prevents flu the year that we give the vaccine, but also prevents flu the second year, the third year and the fourth year. Right. So just to prove that we have a vaccine that protects for four years requires four years of follow up.

[B]

So are you optimistic?

[C]

I am. If not, I will not be working on it. But who knows, I also try not to become depressive at the end. This doesn't, doesn't move forward. Right. At least, you know, I really would love if we can prove that this is the way for a flu vaccine. But you know, to me, the discovery process, you know, to me is very exciting. Also, whether we can translate it for the good of humanity, even better. But just to find new mechanisms is very rewarding for scientists.

[B]

Adolfo, thank you so much for talking to us today.

[C]

Okay, good.

[B]

If you liked this episode, check out our episode on a vaccine trial that could end hiv. We'll put a link in our show notes. This episode was Produced by Burleigh McCoy, edited by showrunner Rebecca Ramirez, and fact checked by Tyler Jones. The audio engineer was Maggie Luthar. I'm Regina Barber. Thank you for listening to Short Wave from npr.

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