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What the CDC is doing to monitor and protect against bird flu

The U.S. Department of Agriculture says cows in multiple states have tested positive for bird flu.
Charlie Litchfield
The U.S. Department of Agriculture says cows in multiple states have tested positive for bird flu.

On Monday, a person in Texas tested positive for bird flu — also known as the highly pathogenic avian influenza — after coming in contact with dairy cattle presumed to be infected.

The virus, which is highly contagious among wild birds and poultry, has now spread to dairy farms, according to the U.S. Department of Agriculture.

Not only is this the first time that bird flu has been found in dairy cattle, according to the American Veterinary Medical Association, but this is also only the second time a human has contracted the virus in the U.S.

Government and health officials say that the risk to the public remains low, since there have been no recorded instances in the U.S. of human-to-human transmission of avian flu.

All Things Considered host Ari Shapiro spoke to Dr. Mandy Cohen, the director of the Centers for Disease Control and Prevention, about the potential risks and the government's response.

This interview has been lightly edited for length and clarity.

Interview highlights

Ari Shapiro: The CDC says the risk to humans from the H5N1 flu that is driving this outbreak is low. Right now, it appears that the two cases in humans were from contact with sick animals. Do you have any reason to believe that humans could pass this on to each other?

Mandy Cohen: So we have never seen a case of human-to-human spread of avian flu here in the United States. And the version of avian flu that we're seeing in cattle, and in this one human case, is the same strain [H5N1] that we have seen previously in birds. We've never seen that spread human to human. That all being said, [what] we've learned through COVID in our experience is: viruses change, and we need to stay ahead of it. That's why we at CDC and the whole of U.S. government is taking this very seriously and monitoring the situation very closely.

CDC director Mandy Cohen in 2023.
Win McNamee / Getty Images
Getty Images
CDC director Mandy Cohen in 2023.

Shapiro: You say we need to stay ahead of it. Tell us what that involves, what are the steps you're taking?

Cohen: One is obviously working very closely to make sure we're understanding the extent of the spread, how many cattle and farm[s] are involved, and then obviously looking for any humans that are in contact with cattle or sick birds, and testing folks that have symptoms, and making sure that we're understanding if it has spread to other folks. So far, there's only been one case in Texas. The person had very mild symptoms. They're recovering well. But we want to make sure, again, that we are testing folks who may have been in contact.

Shapiro: You said widespread testing is important – is there a risk that cases are going to go under the radar because people are afraid to report? Whether it's farm owners who don't want their operation to be shut down or farm workers who might not have health coverage.

Cohen: We're working closely with our state and local partners, our partners through agriculture and the U.S. Department of Agriculture and farm workers. Again, we want to get ahead of this. So we're trying to talk folks through it and build trust, and folks have really been receptive. We've been particularly working with a lot of the veterinarians that are part of the farms that have been impacted. So far, all working well together.

Shapiro: Cows were not thought to be a species at high risk, and so if the virus is now spreading in cows, what are the chances that it could mutate to become a risk to humans?

Cohen: Well, it is true – this is the first time we've seen avian flu, or "bird flu," in cattle. And, as you know, cows are mammals, so this is a new reservoir or a group of animals that we are seeing this virus in. And that just means more opportunity for this virus to mutate and change. And that's what we want to make sure we are continuing to stay ahead of.

Shapiro: Monitoring whether it continues to spread and evolve is one thing – preparing for the possibility that it might is another. In a New York Times opinion piece, columnist Zeynep Tufekci said the government needs to gear up to potentially mass produce vaccines quickly. Do you agree with that?

Cohen: Well, the good news is the United States has been preparing for avian flu outbreaks for more than 20 years. We've invested in our ability to test for this, to prevent it and to treat it. And we know that the strain we're seeing right now is the same strain we have seen before. And we believe from all of our laboratory testing that our test will pick this up. Our treatment, which is Tamiflu, which we have both doses in stockpile and around the country, works. And we even have vaccine candidates that are ready to go. So it's very different than what we experienced, for example, at the beginning of COVID, when we're seeing a brand new novel virus where we didn't have tests, we didn't have treatment and we didn't have vaccine.

Shapiro: But just specifically, if it does take time to mass produce vaccines, is that something the U.S. should be doing in earnest right now on the chance that the virus evolves?

Cohen: We have never seen a transmission from a human-to-human. That is something we are watching for very closely. And so there may be trigger points where we would move to thinking about scaling up vaccine. But remember, there's always a tradeoff there – if we move to manufacturing one type of vaccine, it may be at the expense of being able to manufacture that vaccine for the seasonal flu. Again, something that also impacts us. So, we have the ability to scale up if we need to. And again, we've already started down that process and we'll keep monitoring to see if we need to trigger and do that.

Shapiro: The cases so far have all been in dairy cows. Should people be concerned about consuming milk and other dairy products?

Cohen: [The] FDA has indicated that our milk supply is safe because of the pasteurization process. Unpasteurized and raw milk remains a risk, but the vast majority of our milk supply is safe because of pasteurization.

Copyright 2024 NPR

Ari Shapiro has been one of the hosts of All Things Considered, NPR's award-winning afternoon newsmagazine, since 2015. During his first two years on the program, listenership to All Things Considered grew at an unprecedented rate, with more people tuning in during a typical quarter-hour than any other program on the radio.
Erika Ryan
Erika Ryan is a producer for All Things Considered. She joined NPR after spending 4 years at CNN, where she worked for various shows and CNN.com in Atlanta and Washington, D.C. Ryan began her career in journalism as a print reporter covering arts and culture. She's a graduate of the University of South Carolina, and currently lives in Washington, D.C., with her dog, Millie.