Short Wave - How a single flu shot could protect you for decades

Episode Date: June 10, 2026

Every year, tens of millions of people in the U.S. get the flu vaccine. That’s because the virus changes year-to-year and protection only lasts around six months. Adolfo Garcia-Sastre wants to change that. He’s one scientist working on a universal flu vaccine that could provide decades of protection against all flu illnesses – but only if his team can find the resources that disappeared when U.S. funding dipped.If you liked this episode, listen to our episode on a vaccine trial that could end HIV.Interested in more medical innovations? Email us your question at [e-mail] 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.See 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

You're listening to Shortwave from NPR. The Centers for Disease Control and Prevention estimates that anywhere from 24,000 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. There is more than 100 potential pandemic flu viruses that could start the pandemic. That's Adolfo Garcia-Sastri, a viral immunologist at the ICANN 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. 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 next year and this year, but also will prevent

pandemic influenza from an animal reservoir. 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. But he says,

the virus cannot change completely. If not, we will not recognize it as influenza. 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. Today 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. Okay, Adolfo, what about the flu virus impacts why we need? a yearly vaccine. Yeah, so that's because the virus changed 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 hemagglutinine, and that's H1 will be hemaglutinine subtype 1, ACE3 will be hemaglutin in type 3.

All these three variants 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 B's causing infections in humans. So flu A, which comes into H subtypes and then B's. Okay. So we need three components, right? But each one of these viruses change every year. And they do so to avoid pre-existing immunity.

Right. And the vaccine tries to cover the strains that are circulating. So we make the vaccine for whatever it's going to be circulating this year. And the prediction come from the surveillance that has been done for influenza to see what is circulating at any time in the, the year. And sometimes we miss it for at least one of the components. This year, for example, we miss it for H-3s. There was this newest strain that became quickly very, very prevalent, and this one was not very well covered by the history component of the vaccine. Still, it provides

you some efficacy, but instead of having perhaps an efficacy of 70% prevention from disease, then it goes down to 30% because it's mismatch. 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? 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 conserved areas. The parts of the influenza virus that doesn't change. They don't change, that's correct. That's what I mean by conserve. But not every conserved 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, as imagine, you know, that flu is a cow. That's a cow. So let's imagine it's a cow. Okay. 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, they say that, right? And then the cow cannot do damage or the feet. Right. Then even if they kick you, they cannot do damage. But if you cover the tail, well, the cow cannot give you any damage with the tail. Right.

So there are some areas in the virus that we call non-protective. So we need to find the protective areas of the virus that are conserved. And protective. Yeah. Okay. And then we need to induce an immune response against these conserve areas by deciding a vaccine that is different from the ones that we have, because the ones that we have only induce good responses against the variable areas. Variable areas, the parts of the virus that change. Yeah, which are very good.

But they don't protect you against future strains. They don't protect you against pandemic streets. The science hasn't gotten here yet because we haven't been able to find those regions or do. Well, it took a while. Okay. It took a one. Okay. Now we have some candidates.

Okay. We have candidates. And then then we have to make a vaccine that will react to these regions that don't change. Yeah, correct. Okay. So your lab is working on a universal flu vaccine and you just finished phase one trial. What did phase one tell you? So phase one, the main thing that tells you is safety.

And the second thing that I tell you whether you get the immune response that you think is good for the vaccine. Yeah. Did you? Yeah. In phase one, we got an 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. So have you started phase two? Phase two, we have not started. We have been in phase one.

What's holding up phase two? Money, mainly money. Yeah. They are very costly. and there was a NIH program that I 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 is unclear whether it's going to restart. Was this part of the recent government cuts that happened in the last year? Well, it was not really a cut, but there has been also a lot of slow. down 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 it 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. So what will happen to all your material, all those vaccines in that time? 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 two, phase one clinical trials that we still need to do. How does that feel that you could make something that could help so many people, but it gets stopped by money? Well, it's frustrating, right? I think the money is there, 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. You know, 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 if we want to, in the future, to do it, we need to start again making this material. Are you optimistic that there will be this universal flu vaccine, like, created in your lifetime? In my lifetime, I hope so. But in the next five years, I think, is a big challenge. 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 four year, right?

So just to prove that we have a vaccine that protects for four years, requires four years of follow-up. So are you optimistic? 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 move forward, right? At least, you know, I really will 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 it's very exciting also,

whether we can translate it in for the good of humanity, even better. But just to find new mechanisms is very rewarding for scientists. Adolfo, thank you so much for talking to us today. Okay. Good. If you like 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 Burley McCoy, edited by a showrunner Rebecca Ramirez and fact-checked by Tyler Jones. The audio engineer was Maggie Luthor.

I'm Regina Barber. Thank you for listening to Shortwave from NPR.