The Latest On Bird Flu

Bird flu, or avian influenza, is spreading among livestock and other mammals in the United States, raising concerns that another pandemic may be looming. Last month, California declared a state of emergency due to rising cases in dairy cattle, and there have been over 65 human cases in the U. S. during this outbreak. While cases have been largely mild and risk to the public is still considered low, scientists warn it could evolve and become more dangerous. Curious about other health updates? Email us at [email protected] mailto:[email protected]. 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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• 0:22Regina Barber?

  Hey, Short Wavers. Regina Barber here to talk about the bird flu, also known as avian influenza. It's spreading among livestock and other mammals in the US and raising fears that another pandemic is in our future. So, bird flu got into the news when a farmworker was infected in the spring of last year. And last month, California declared a state of emergency due to rising cases in dairy cattle. So here to parse through the data is health correspondent Will Stone. Hey, Will.

• 0:48Speaker 02

  Hey, Gina.

• 0:49Regina Barber?

  Will, you've been monitoring bird flu ever since the first case almost a year ago. And there's so much to cover. But can we start with like a refresher? What's happened like so far?

• 0:59Speaker 02

  Sure thing. So there have been more than 65 human cases in the US during this current outbreak. And there's a reason to believe that's probably an undercount. Luckily, these have largely been mild. Many are presenting as conjunctivitis and sometimes as a cold, although there have been a few that have resulted in serious illness. And just to refresh listeners, a bird flu infection starts when the protein on the virus binds to a receptor on the cell it wants to take over. This is the HA protein on the bird flu virus. Luckily, the version of H5N1 spreading in cattle has not evolved to target the receptors that dominate upper airways in humans, in the way that people get infected with seasonal influenza every year.

• 1:44Speaker 02

  That would be a key step in the path to this becoming a pandemic.

• 1:48Regina Barber?

  But scientists warn it could evolve, right? And be more dangerous. I mean, do you have a sense of how worried scientists are?

• 1:55Speaker 02

  Yeah. Scientists who study influenza have told me they are about as worried as they've ever been about a potential bird flu pandemic. Now, that doesn't mean it will necessarily happen. Dr. Jesse Goodman, an infectious disease physician at Georgetown University and a former FDA official, put it this way to me.

• 2:14Speaker 03

  This is like some brush burning around your house that you better pay attention to because it could turn into something else.

• 2:24Regina Barber?

  So today on the show, paying attention to bird flu.

• 2:29Regina Barber?

  We get into the infection landscape, how the government is preparing, and the future of immunity. I'm Regina Barber, and you're listening to Short Wave, the science podcast from NPR.

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• 3:56Regina Barber?

  OK, well, let's back up. So in March 2024, almost a year ago, researchers found bird flu in cattle. But the global outbreak of bird flu has been going on for a while, right?

• 4:06Speaker 02

  Yeah, this strain of H5N1 bird flu that's driving the current outbreak worldwide, it emerged in 2020. It's known as highly pathogenic avian influenza because of how lethal it is in poultry. It eventually started spreading in North America in late 2021. This was in wild migratory birds, but it eventually found its way onto poultry farms. So we started to see outbreaks there. These viruses technically belong to a group or a clade known as 2.3.4.4B. Not the easiest name to remember.

• 4:38Regina Barber?

  No, I'm not going to remember.

• 4:40Speaker 02

  Yeah, that's okay. Just know that this strain is concerning because scientists had been seeing more and more mammals getting infected than we would typically expect with bird flu. So it was a big surprise when it started spreading widely in dairy cattle. That was unprecedented. Along with the spread in cattle and poultry farms, you know, all of this gives the virus more opportunities to spill over into humans and, you know, potentially mutate.

• 5:09Regina Barber?

  So, big picture, what's happening with the virus?

• 5:13Speaker 02

  So it's all over. It's still infecting dairy herds in the US. A lot of that is happening in California. It's still being detected in poultry flocks all over the country because wild birds, you know, end up mixing in the poultry farms and then it just tears through those facilities. Like I mentioned earlier, about 65 people, a little over that, have caught the virus so far. A few of those cases in humans have been severe. There was a teenager in Canada who ended up in critical condition and almost died. Another case was in a resident of Louisiana who ultimately did die. The person did have some underlying medical conditions, we were told by health officials. What's notable is that both of these severe cases were not related to the virus circulating cattle.

• 5:57Speaker 02

  These viruses belong to a genetic lineage found in birds and poultry. It's still part of the same 2344B family we mentioned earlier, but it's a different genotype from the cattle virus. And it's possible there's something about this genotype that explains why these more severe cases are associated with it. This is an area that scientists are looking into.

• 6:21Regina Barber?

  Wow. Okay, but since cases are generally with people working with animals, should like the rest of us, should we be concerned?

• 6:30Speaker 02

  Right now, the risk to the general public is still considered low. The way you catch this, as you mentioned, was close contact with infected animals. Dairy workers appear to be infected during the process of milking. Raw milk harbors a lot of virus. We know that. And the suspicion is that people who are milking the cattle, they're getting it on their face, it's getting aerosolized, and basically, that's how they're becoming infected.

• 6:53Regina Barber?

  Okay, so it sounds like scientists like know how people are getting infected with bird flu.

• 6:58Speaker 02

  Well, for the most part. There have been a few cases in the US where the source of infection was not identified. There was actually a child in San Francisco recently. There was a person in Missouri last year. That case in Canada, they also didn't know the exact source.

• 7:14Regina Barber?

  Right.

• 7:15Speaker 02

  Yeah, this is concerning. We like to know how someone got infected. But at this point, it doesn't look like any of the other close contacts of these people were infected and that it was spreading between people. So the risk calculation could change quickly if we do see evidence of human-to-human spread. We're not there yet, though.

• 7:36Regina Barber?

  So what is the government doing to prepare for like that possibility, this human-to-human spread?

• 7:41Speaker 02

  I would say the biggest action is around vaccines. No one in the US is being vaccinated for bird flu yet. But the US does have three H5N1 vaccines that were licensed and approved years ago because of concerns about future bird flu pandemics. Those shots were developed to target older strains of the virus. There is some lab research that indicates they could still be protective against this newer version. But the federal government has actually been working to update those vaccines to target the strain that's circulating now better. This is kind of what we do with flu vaccine. You know, we update the strain every year to try to get a good match.

• 8:24Speaker 02

  So the federal government has put in orders with vaccine makers for these updated shots. It's expected there'll be about 10 million of them stockpiled by early spring. These are two dose shots. So clearly, Gina, this is not nearly enough.

• 8:38Regina Barber?

  Mm-hmm. I mean, if the bird flu does escalate into this like big crisis, we're gonna need to vaccinate like the whole population. So we're gonna need like so much more than 10 million vaccines.

• 8:49Speaker 02

  Yeah, only compounding the issue here is that these vaccines rely on older technology. And so they can't just be churned out, you know, in a rapid timeframe.

• 9:00Regina Barber?

  Okay.

• 9:01Speaker 02

  And making things even more difficult is that the federal government doesn't want to preemptively make hundreds of millions of these shots because if bird flu does evolve significantly and can spread among humans, we expect it's going to look different and they may need to update the shot again. So it's a tricky situation of kind of cautiously monitoring the situation, but not going all in on vaccines that we have yet.

• 9:28Regina Barber?

  You talk about this like old technology. Is the government investing in like mRNA vaccine tech, which we used for like the COVID vaccines?

• 9:35Speaker 02

  It is. That's actually one of the main things they're doing in the development of new vaccines, hoping that we can have some shots ready that could be produced a lot faster with mRNA technology. The US Department of Health and Human Services actually announced this month that they've awarded over $500 million to Moderna, which came up

• 9:58Regina Barber?

  Oh, wow.

• 9:59Speaker 02

  with the COVID vaccine to work on influenza vaccines, you know, including to protect against bird flu. There's still work going on in clinical trials. So we don't have these mRNA shots, you know, stockpiled and ready to go. But if there's an emergency, perhaps we could see a big all out government effort like we did during COVID with Operation Warp Speed.

• 10:22Regina Barber?

  So that's all happening like right now, this, this kind of planning. We have a new administration that just took over. Do we expect this work to continue?

• 10:31Speaker 02

  It's a good question. The Trump administration has been largely silent on bird flu in general. Scientists I've interviewed are deeply concerned about Trump's pick to lead the Department of Health and Human Services, Robert F. Kennedy Jr. For years, Kennedy led an advocacy group that's a big player in the anti vaccine movement. And recently was discovered that in the spring of 2021, Kennedy actually filed a citizen's petition on behalf of That advocacy group to the FDA. And in it, he requested the agency revoke the authorizations for the COVID vaccine for all demographic groups. Basically, this would have made the shot unavailable. Of course, you know, the FDA denied this request.

• 11:14Speaker 02

  But Kennedy has an extensive history of making inaccurate and misleading statements on vaccines. And he's actually already made comments undermining trust in the existing bird flu vaccines. We did reach out to the transition team for comment about their plans on bird flu and vaccines, but did not hear back.

• 11:32Regina Barber?

  So Will, since bird flu hasn't been spread widely in humans yet, are there chances we have immunity? That would be nice.

• 11:40Speaker 02

  It would be nice. You know, the CDC has looked at blood samples and said, you know, there's little to no immunity to H5N1 virus in the population.

• 11:50Regina Barber?

  Okay.

• 11:51Speaker 02

  But, you know, it gets a little more complicated because we have been exposed to other flu viruses. And there is likely some degree of cross immunity against H5N1 because of, you know, things like H1N1 that we've faced before. I spoke with a virologist Florian Kramer at Mount Sinai about this because he's done some work showing that a type of immune cell called a T cell may be able to kick in and help us a bit if we were to be confronted with bird flu.

• 12:19Speaker 05

  There's certainly preexisting immunity. The preexisting immunity does very likely not protect us as a population from a new pandemic should H5N1 become pandemic. But it might give us some protection against severe disease. So that's what I think what the situation is. How much protection, how to quantify that? That's really hard to say, right?

• 12:43Speaker 02

  And Florian actually says it's possible that this cross immunity could help explain why the infections in humans we've seen have largely been mild. This is kind of speculation at this point. There's no way to know for sure. And as he alluded to at the end there, we cannot bank on this cross immunity just protecting us entirely from bird flu. It just gives us some reassurance that we're better off than if we hadn't been exposed to any flu virus.

• 13:12Regina Barber?

  So are there steps we should all be taking right now?

• 13:17Speaker 02

  If you are not in the livestock or chicken business, there's no imminent risk today.

• 13:23Regina Barber?

  OK.

• 13:23Speaker 02

  Scientists say it's unlikely you're going to get infected from a stray piece of bird poop or from touching your bird feeder, although we don't necessarily have data on that. It really would take quite a bit of exposure for you to get sick from it. And basically, the guidance is if you are messing with your bird feeder or touching bird poop, just wash your hands after. Don't touch your face immediately.

• 13:49Regina Barber?

  Which is good, general advice, I think.

• 13:51Speaker 02

  Yes.

• 13:55Regina Barber?

  Will, thank you so much for coming to talk with us about bird flu.

• 13:58Speaker 02

  Of course, Gina, anytime.

• 14:02Regina Barber?

  This episode was produced by Rachel Carlson. It was edited by showrunner Rebecca Ramirez, and Robert Rodriguez was the audio engineer. Beth Donovan is our senior director, and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Short Wave from NPR.

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