Humans in Public Health: H5N1 Bird Flu

In this special bonus episode of Humans in Public Health, we talk with Professor Jennifer Nuzzo, director of the Pandemic Center at Brown University, about the rising concerns about bird flu in the United States.

Listen to the Episode

Today we have a timely bonus episode to bring you up to speed about something you might have seen in the news – bird flu. 

To explain what’s going on we invited Brown University professor Jennifer Nuzzo to the show. Jennifer is a professor of epidemiology and the director of the Pandemic Center at Brown University. 

Megan Hall  00:25  

Jennifer Nuzzo Thank you so much for coming in today.

Jennifer Nuzzo  00:28 

Thanks for having me.

Megan Hall  00:29 

So let's just get to the basics. First, what is bird flu.

Jennifer Nuzzo  00:33  

So bird flu is a type of influenza virus that has been mostly affecting birds and other wildlife, it's been on our radar for more than 20 years, there have been some human cases that have occurred over that time. But these, by and large, have occurred in people who have had contact with infected animals. So there are the sporadic infections, there have been almost 900 over this 20 year period. So not a small number, but not anything like we see with seasonal influenza. 

Megan Hall  01:06

Okay, so why are we hearing about bird flu in the news right now?

Jennifer Nuzzo  01:10

Yeah, so it's been a virus that we've been watching and worrying about for 20 years. But it's kind of come back into the news in the last year or so in part, because in the last year, we've seen a really rapid expansion in terms of where on the globe, we're finding this virus, and also a rapid expansion in terms of the number of animal species that are affected by this virus. So as I said, it's largely been a virus that has affected birds. But over the last year, we have seen the virus be capable of infecting many more animal species, including mammals. And once we start seeing this virus show up in mammals that increases our worries that it might be getting better capable of infecting mammals and humans or a mammal, So that's one reason why we worry about it. 

And recently, you've heard about this virus in the news, because we found the virus in cows, that was surprise number one, we hadn't previously seen this virus in cows before. And a dairy worker, someone who was exposed to a dairy cow also was determined to have been infected by the virus. And so seeing a human being who has close contact with an infected cow, that increased worries one because, you know, again, we don't want people getting this virus, but two it just raises concerns that if we let this virus continue to circulate around the world, it could get better capable of infecting humans.

Megan Hall  02:30  

So can you help put this into perspective for me? Because there's always the struggle to balance keeping people informed with wanting to avoid alarming people. So, where would you say bird flu is right now on a scale of like, common flu to COVID, 19 in  2020? Like, where are we at?

Jennifer Nuzzo  02:47

Yeah, so we're nowhere near either of those. When you hear sort of experts worrying about this virus, what you're hearing is worrying about a future scenario that hasn't yet happened, and wanting to make sure that we take action to prevent that future scenario from happening. Now, this virus does present a threat today. But right now that threat is to the people who have exposure to infected animals. And I do very much worry about farm workers and people who are exposed to raw milk because we have found the virus and raw milk, I worry about needing to protect them. But I don't worry right now for the general public that isn't regularly in contact with animals that are likely to be infected. 

Megan Hall  03:28 

What do we know about bird flu in milk? Do people need to be worried about drinking milk?

Jennifer Nuzzo  03:32 

So short answer no. About a week or so ago, there was a headline that they had found evidence of genetic material in milk that had been pasteurized. And that's not really surprising, because if you know that the virus is in raw milk, and it had been found in raw milk from the infected dairy cows, what pasteurization does is it basically heats the milk, it doesn't remove the genetic material of the virus, but it makes the virus inactive so that it can't infect us. So follow up testing of the pasteurized milk was not able to grow virus from it. So that gives us good confidence that pasteurized milk cannot hurt people. Public health experts have long advised against consuming raw milk. And this is just another reason not to consume raw milk.

Megan Hall  04:19 

So if you think it's really trendy and you want to drink raw milk, this is not the time to start. 

Jennifer Nuzzo 04:24


Megan Hall 04:26

What do we know about how this is spread?

Jennifer Nuzzo  04:29 

Yeah, so that's been a little bit of a mystery. And it's still a mystery. It is currently thought that there was probably one introduction to dairy cows, but there's a little bit of uncertainty around that. And then it has spread to cows in other states, don't fully understand how that happened, though there is some thought that the movement of cows has played a role. I would say, I'm not terribly satisfied with the answers that have been given, and, you know, I don't think the movement of cows fully explains it, or at least I haven't seen compelling evidence that that's it. So I basically think that there's a lot more to learn. And what has been challenging is that we know that surveillance for this virus in cows is just woefully inadequate. You know, there's deep disincentives to test these animals. And also the testing that's been done so far is really been oriented around protecting the industry rather than trying to protect the humans who may be exposed to the virus.

Megan Hall  05:27  

We learned so much about how viruses are spread with COVID. And we eventually learned that you know, it's in the air. So the best way to protect yourself is through masks. But do we know if you know, a cow was next to a bird that was infected? I mean, how did it get from the bird to the cow, or we have no idea. 

Jennifer Nuzzo  05:44  

So we don't know, we don't know that. We don't know how it spread from cow to cow, though we do believe that there's been cow to cow transmission. We don't know if it's been through milking operations, that somehow there might be a contamination or an aerosolization of the virus. also, the movement of cows between states may have played a role. But really, I think it's not clear enough to understand. In the worker who was infected, the infection was mild, it was conjunctivitis so an eye infection. And some people have raised the possibility that that may have been, you know, maybe touched raw milk and touched eye, we don't fully know. But you know, there is the worry that, you know, more serious infections can occur, because of the nearly 900 people who have been infected with this virus so far, again, over the last 20 years, about half have died. So this is not an historically mild virus. And so while it's, you know, better that this case that we found recently was mild, we can't say that future cases will be. 

Megan Hall  06:45 

So what is the government doing to respond to this and prevent the spread?

Jennifer Nuzzo  06:50  

So the biggest change that we've seen so far is that the USDA, the US Department of Agriculture has changed its policy for testing cows. They've implemented a policy that some people are calling Test To Move, meaning that they are now requiring that cows that are going to move between states have to be tested. So that's a new requirement. And there's also a requirement that the test results will be reported to the USDA. That is an improvement because before and still largely, testing is pretty much voluntary, and it's otherwise restricted to cows with symptoms.

We know from data from North Carolina, that cows without symptoms may also be infected, they can test positive. So there's a number of ways why this new policy while, somewhat of an improvement is not adequate to figure out where in the country the virus is and where it isn't. But also not adequate to protect farmworkers. Because if you're only testing a cow with symptoms right before it is going to move between states and you have to send that specimen out to a laboratory. It's going to be some time before you get that test results. And what that means is by the time you find out that that cows been infected, it's very likely that a worker has been exposed to it. 

Megan Hall  08:03  

So if you were in charge, how would you be responding? 

Jennifer Nuzzo  08:07 

Well, I think one of the things we need is tests that can be done on the farm. So we get test results more quickly, so that we can perform tests much more frequently. And that we can perform them for the purposes of making sure a cow’s not sick before someone has exposure to them, or to encourage those who are likely to be around these cows to make sure they have personal protective equipment on. The other thing is to think about protecting farm workers more directly. The US government has undertaken some effort to develop and stockpile H5N1 vaccines. 

Megan Hall  08:39  

And H5N1 is the technical term for this bird flu.

Jennifer Nuzzo  08:43  

Yeah, so that's, that's the name that we are giving this virus. The government has vaccines for this, it’s not quite ready for human use. They are keeping these vaccines in case the virus does become capable of spreading between people more easily, and so that we could, you know, potentially start vaccinating earlier than, if you remember, back in COVID, it was about a year before vaccines became available. This effort that's gone on will make it faster to get vaccines out. But in my view, we should be thinking about using these vaccines now to protect farmworkers that we know have been exposed to what has been historically a deadly virus.

Megan Hall  09:20 

The last time we spoke was in 2022. And you were just coming to Brown to set up this pandemic center. How does the mission of your center fit into responding to something like a bird flu? Like this seems like sort of your work in action? 

Jennifer Nuzzo  09:36 

Yes, it is. And I think when we talked, we talked about why COVID-19 was not going to be our last pandemic threat, why the conditions of the world were such that we're gonna keep seeing these new viruses emerge and potentially threaten us. And that the goal for preparing for them would be that we would have the tools and policies and practices that we need, so that when they do occur, we could respond quickly, we could respond effectively, such that we kind of take off the table, the ability of these pathogens to upend our lives in the way that COVID-19 was capable of doing. And so, you know, I think, with the ending of COVID-19 as a kind of global emergency, I think many people were tempted to think that we were sort of done. That the worst was behind us and we really didn't have to worry about these scenarios anymore.

Since I've gotten to Brown there have been a number of different things that have occurred since the pathogen so we had a historically significant epidemic of another virus, respiratory syncytial virus that really, you know, overwhelmed a number of hospitals around the country. We had a very rapid and vigorous flu season that happened. We had a pretty unprecedented global epidemic of M-pox, a virus formerly called Monkeypox. This H5N1 is also concerning and yet another one of these infectious disease threats that we have to think about and respond to. So, it's just part of the operating conditions of our lives. We live in an age of pandemic threats, we're going to keep seeing new events occur, that make us worried that another pandemic could happen, and we need to be ready to respond quickly, so that we don't allow the worst to happen. 

Megan Hall  11:16

So instead of seeing these pathogens as sort of the specter of another COVID, we kind of have to see it as business as usual. Like they're just gonna keep coming. 

Jennifer Nuzzo  11:25  

Yeah, I mean, I think of them sort of as recurring hazards. Just like if you live in, you know, the southern coastal states, you'd be regularly thinking about getting ready for a hurricane. If you live in the western states, you worry about wildfires, you know, there are recurring hazards, that we get ready for, that we plan for so that when they happen, we don't let them just completely consume us, that we can work to protect ourselves and to prevent the worst from happening. 

Megan Hall  11:53  

Great. Well, we're gonna wrap up, but before we leave, I just want to get sort of a takeaway from you, for our listeners who are trying to kind of weigh how worried they should be. What's your kind of final message to people as they're learning about this latest version of bird flu?

Jennifer Nuzzo  12:08 

Yeah, so what I tell people is if you're not someone who has exposure to animals that are likely to be infected, this is not something you have to put on your worry list. However, when you hear people talking about it publicly, they're talking about it publicly because we want the government and other partners to take action to prevent this from becoming a bigger threat. I have been worrying about this virus for 20 years, I have worried that this virus could cause a pandemic for 20 years. It hasn't happened yet. That doesn't mean it won't just because it hasn't happened doesn't mean it won't happen. But what it means is that we have to get ready so that we could take off the table worry about this virus for good.

Megan Hall  12:46 

Great. Well, Jennifer Nuzzo. Thank you for coming in today.

Jennifer Nuzzo  12:49 

Thanks so much for having me.