A few weeks ago, we brought you an episode about the outbreak of bird flu caused by the H5N1 virus. As you probably know by now, it's been spreading in dairy cattle in some parts of the country. I promised that I was going to monitor the situation and talk to experts on the ground about what the spread of the virus might mean for animals and for humans. And I wanted to be really honest with you about any updates. So here's what we know. It is still being transmitted primarily between wild birds, livestock and other mammals, including now foxes, raccoons and mice. But there have been some new developments. For the first time, the CDC has confirmed that a person infected with bird flu in the United States is experiencing acute respiratory symptoms. This person represents the third human case, all of them farm workers, all of them tied to the dairy cattle outbreak. The first two patients, as you may remember, only had mild symptoms related to the eyes.

First of all, I want to be clear. We are not ringing any alarm bells here, but we do want you to be aware of what is happening. To be informed and to be prepared for what may come. So far, the bird flu does not appear to be transmitting from humans to humans in this outbreak. But at the same time it is evolving. That third farm worker I just mentioned, the one who developed respiratory symptoms. An unprecedented number of mammals now infected so far. That kind of means this thing is changing. It's on the move. And so of course, probably like you, I have questions. If humans do get sick from this strain of bird flu, how bad could it get? How sick would they get? Do we have an effective treatment? Are we doing enough to contain this outbreak right now? And what is the plan if the situation escalates? My next guest thinks as a starting point, we need to be paying more attention.

This is completely different than anything we've seen even up until the last two years.

'That's Rick Bright. He's a virologist and an immunologist. He's been studying the bird flu since the 1997 outbreak in Hong Kong. He's also the former head of the Biomedical Advanced Research and Development Authority - Barda. He's an expert in public health emergency responses. And he says more testing is needed to understand how much has this really spread in humans. I'm going to talk to Rick about whether more testing actually translates to making us safer. I also want to ask him who's in charge of the response, and how do we keep this from becoming another pandemic? I'm Dr. Sanjay Gupta, CNN's Chief Medical Correspondent. And this is Chasing Life.

'Do we have a sense of how much this has spread in humans? As of now, we know who got sick. There's been at least three people. Two of them had primarily eye symptoms - conjunctivitis, call it pink eye. But someone in my home state of Michigan had respiratory symptoms as well. Do you think, and I realize this is speculative, but do you think that that is tip of the iceberg? Or are we doing a good enough job sort of catching these?

I really think that's a tip of the iceberg. We are not doing enough testing, or even the right kind of testing to get a better answer to that question. It's really unusual that we would find just one or two cases with so much virus prevalent in so many places as such close contact to the source, such as the infected cow or the milk supply. And so it's more likely that we're only detecting the most severe cases, even though they haven't been that severe, thankfully. But we're testing those cases that are either more severe or those that are more concerned and therefore they seek medical treatment. Or perhaps they're on a farm that is monitoring more closely. So there's a range of activities happening, but what's not happening that's critical is serology testing. I mean, sampling the blood from people who are on the farm in close contact with infected animals and infected humans, and also sampling the blood of those who in their household and in their community and looking for antibodies. It's very easy, then, to tell who might have been infected with this virus, and very likely had very mild symptoms or no symptoms at all. That would be extremely enlightening to us as we manage this outbreak just to have that bit of information.

And so if you found, let's say a lot of people who had antibodies, meaning that they had been exposed at some point, but they really didn't get sick. In some ways that might be reassuring in the sense that that means the denominator of people who have been exposed to this but didn't get sick is is much higher.

That's exactly right. However, I want to caution that it's a snapshot in time, and these are people who are getting infected with a primarily avian influenza virus. So what could also be happening in people who are infected with low symptoms or no symptoms is it gives an opportunity for that virus to start mutating and adapting to people. And when that virus adapts to people better, it can cause a more severe infection and illness and spread. And even immunity to perhaps an older avian influenza virus may not protect you from a more human like H5 virus once it starts to spread. So we can't let some level of antibodies or exposure fool us into complacency that we're better prepared if this were to change to a human virus.

You seem concerned. You retweeted something about mice and how it's out of control with mice, because these mice could get into residential properties, ones that are carrying H5N1. Is there a red flag or something that you are really sort of looking out for in the back of your mind that would tell you that this has now transitioned into something that is no longer of low concern, but is medium or at least or even higher concern?

Well, yes, there is. You know, I'm concerned when we find the virus in more mammalian species and the closer those mammalian species are to people. However, these are still avian like viruses because of the genetic composition. So what's really critical to monitor are the genetic sequences of these viruses as they continue to infect more species, or even spread within the same species. More cow infections could allow that virus to adapt to mammals, and in more cats and more alpacas and more foxes and more mice. All of those are mammals, and all of those give that virus opportunity to mutate. So it's really critical that we are getting sequence data, genetic sequence data from each of these viruses, from each of these species as quickly as possible. If we were to see probably 1 or 2 or maybe three mutations of the virus from any of those species that indicate it has adapted to better infection or transmission among mammals, particularly in people, that would be a red flag to indicate we need to start moving much faster than what we're doing now.

How, how many different types of mammals have have now been infected by this?

Hundreds. You know, it's really interesting. I think it's 40 species. I bet in hundreds of different animals and mammals around the world.

Going back to your 1997 days in Hong Kong. I mean, how what was it like then? I mean, do you have any sense of how many different types of mammals were infected then?

You know, I don't think mammals were infected at the time. I think it was really...

All birds.

Infection in wild birds and that case and it spilled over. Then the concern was spillover from wild birds into domestic poultry. And so we had major concerns. We watched that happen over the last 27 years in the United States. Over the last two years, we've seen a significant increase in the number of domestic poultry flocks infected with H5N1. And we have effectively been able to manage or mitigate further spread by basically culling or killing all the flock birds on that farm and decontaminating that area before new birds are allowed to be brought back onto that farm. So we've been effectively managing it. It is still continuing to spread and adapt, and never before anywhere around the world have we seen this many mammals infected at all at once in a wide geographic region of a country this close to people. So this is completely different than anything we've seen even up until the last two years.

Do you ask yourself why here in the United States, is it so prevalent and not other countries? Is there an answer to that?

Why is it more prevalent in dairy cattle in the United States? I mean, I it's not surprising that, the virus is in the United States and affecting poultry flocks. That's happening globally. What is really surprising is to see a spillover from potentially a wild bird, into cattle. And then what's shocking is that somehow we did not make a decision to control or contain the virus at that point. A decision was made, consciously or unconsciously, to allow the farmers to transport infected cows across the country. So instead of having a single site, a single source of infection and virus prevalence, perhaps on one cow or one farm, a decision was made to distribute those infected cows across our country without testing, without monitoring, and therefore, once it went into these very populous areas where we have a lot of dairy cattle, it is no surprise now to see that it is basically in an uncontrolled spread and among dairy cattle and nearby mammals on those farms.

There was this article on Scientific American basically saying that like trust in public health institutions is near an all time low, and that makes us vulnerable as well to another outbreak, epidemic, pandemic even. Are there like if public health leaders are coming to you and trying to get guidance, what would you tell them to, how should they behave in terms of wanting to stay ahead of this, but also making sure people will actually listen to what they're saying?

You know, I think it's important that we level with the public. I think Americans and the world can handle the truth. I think we have to talk about how difficult the road ahead can be. If this were to get out of hand, and how helpful it will be if we can enlist everyone to help in managing and controlling it at the stage it is in now, and if it were to get worse.

Up next we're going to talk about vaccines and who is responsible for keeping us safe. We'll be right back.

Finland, as you probably have heard, is preparing to offer bird flu vaccines for people who are considered high risk, which again, that may be a little bit hard to define, but nevertheless they want to make those vaccines available. Is that something that should be happening in the United States as well?

'I think so, yes. We have vaccines. We have licensed pre-pandemic influenza vaccines already made for ten years when I was leading BARDA influenza division and our pandemic response. So we know the safety of those vaccines, we know how they work, and we know that even if a person has given one dose of an older strain of an influenza vaccine for H5N1 and then given a second dose, they're boosting dose with the most closely matching strain that would circulate during a pandemic. That person would still make a robust immune response to what would be circulating at that time. So there's solid science to show that it makes sense to offer a vaccine to those at high risk.

'If the vaccine were to be made available in the United States, high risk, again, it's a I imagine a little bit of a changing definition, but farm workers would be considered high risk, I imagine? What about my parents are both in their 80s living in Florida - would they be considered high risk? Who would, Who would slash should get it?

I think right now the highest risk are those in close contact with the virus. So I think your parents in Florida are safe as long as you're not visiting a dairy farm, drinking raw milk or apt to pick up, a sick or dead animal. And so those on the farm are at highest risk. Those who are milking the cows. It's actually important to think about their family members as well. So they could be infected on the farm. They could take that virus home and attack their family members. So they would also be at high risk. And it's not just the dairy farm workers. There are transport drivers who collect this milk and they transport it to pasteurization facilities. And so everyone along that chain are also exposed in higher risk. And then many of these animals at some point go to slaughter. And there are people that are at work in the slaughterhouse as it might be exposed to infected cows as well. And so thinking about where the virus might be and who might come in contact with that virus, that is how I would define highest risk now. Those are the people I would vaccinate or make the vaccine available to. And another thing we did, at the CDC, when we work with these viruses through the many years, is made sure people at high risk had immediate access to antiviral drugs. And so we know that the antiviral drugs we have are most effective if they're used within the first 36 or 48 hours of symptoms, where most people don't seek treatment in that time frame. And it's not easy to get access to those drugs in that time frame. So it's really important to move the drugs closer to the people who are at highest risk. So if they needed to get antiviral treatment, they can get it very quickly.

You know, you worked in the government for for a long time. How would this happen? Let's say someone's listening. Is it the Department of Agriculture? Is it CDC? Is it the White House? Again, I've been reporting on this stuff for over 20 years, and I don't know how to answer that question sometimes. Like, who would actually take the bull by the horns, so to speak, and start making some of this happen? Who's responsible?

Well, I think that that has shifted over the years. I think what I was most encouraged to see this last administration, the Biden administration, put in place an Office of Pandemic Preparedness and Response Policy in the White House. And one of the challenges we've had in managing any outbreak in the past is the question of: Who's in charge and who has that authority to coordinate across departments? And when that authority has resided within a department such as Health and Human Services, it's been particularly challenging to get collaboration and cooperation within the department, let alone trying to align and coordinate Department of Agriculture and Commerce and Trade and Health and Human Services. So by elevating that responsibility to the White House, that's when we would expect to see much better collaboration and coordination. But in that context, I'm still not seeing the thing has happened that really need to happen. And that in calls we have with the departments and the White House, we still see the CDC wringing their hands because they don't have the data they need from the Department of Agriculture. We still see the Department of Agriculture wringing their hands because they haven't figured out how to work efficiently with state departments and local departments of agriculture. So there are still these gaps and disconnects in the coordination. And when you see that, you do wonder: Who's in charge? And what we need to respond effectively from day one throughout this outbreak will be strong leadership from someone to makes decisions and someone who's able to really champion those decisions across departments for coordination. We're still waiting for that to happen.

'I just. Why aren't we doing this stuff? I mean, you know, the United States was, before the Covid pandemic, thought of as the best prepared nation in the world to be able to handle a pandemic. And we know -- and I'm not being glib here, I'm really not. But we know how that turned out. And it's sad, really. So I don't make jokes about that. You you've lost people. I know your mom passed away in August of last year, and it's heartbreaking. Why aren't we doing this?

'You know, it's a big question. And there's we are one of the wealthiest countries in the world. We have the greatest technology. We have the greatest, some of the greatest scientists and public health infrastructure. But we're facing a challenge we haven't faced before, and that is the turf battles between agriculture and commerce and public health. And where commerce and health intersect, there's a huge gap, and trying to protect the economics of selling dairy cattle, export, dairy products, beef products and poultry products. And somehow this one health approach that we all preach about -- the need to better align our surveillance and our response capabilities and our tools between animals and people and the environment -- this is really being dismissed once again in the US. And we're supposed to set the example for the world that the world is looking at us today and asking the question: Why isn't there transparency in the data that are being collected? Why is there a six to eight week lag in sharing critically important genetic sequence data from the viruses collected from animals that are infected with the virus? And why isn't the United States conducting this critical serology study and testing? We should not only be using the tools that we have, but we should be exercising our ability to communicate and reach people at highest risk in those communities and raise awareness on that threat and the things they can do to protect themselves. We should be sharing data readily. We should be modernizing our capabilities and make vaccines better and faster. Additional antiviral drugs and testing. We're just not doing it yet. And that's a big concern for me and for the world.

Coming up: What should you be doing and what shouldn't you be doing? What precautions should you and your family be taking when it comes to H5N1? And is there anything you should be avoiding? We'll be right back. Are there things that you are doing or things that you are now avoiding, given what you know about H5N1? How are you living your life differently?

'I am concerned still about the types of testing that we're doing to ensure our food supply is safe. And so there's a lot of discussion about the safety of milk and the effectiveness of pasteurization. I certainly avoid raw milk and raw milk products. And I have actually made a decision, from my risk assessment and my family, to not drink dairy milk at all, even pasteurized, until we have more information about this outbreak. The FDA and other scientists have done some elegant benchtop experiments showing if they mix some influenza virus into some pasteurized milk, heat will kill influenza viruses. We know that to be true. No surprise. What hasn't happened yet are real pasteurization experiments with large volumes of milk that have been infected with the virus, not just mixed with the virus. We know pasteurization works, but we also know there are limits and constraints on the effectiveness of pasteurization. If we're not doing anything or very little to keep infected milk on the farm, and we're allowing more and more milk as we see more and more herds infected, more and more milk is going into that process of pasteurization. We know at some point it's a matter of a ratio and dilution. And how much virus can our traditional pasteurization experiments or process neutralize? There will be a breakpoint and mistakes do happen. So until I know that we have the right experiments, we know those constraints, and we're doing everything possible to minimize the amount of bias going into that process, I've chosen to take the risk step and not expose myself to milk at all and my family. I know I'll say not everyone has that luxury. Just switch, from dairy milk to to nut-based milk. And I do hope that those who can in the FDA and USDA will step up measures to keep infected milk on their farms, because ultimately, that is what's going to reduce the risk to Americans, with or without pasteurization.

I want to be really responsible here. But what is the message to anyone listening now? And I'm not asking you to divulge anything about your own personal medical history. If there's some reason you consider yourself at higher risk or whatever. But should I not be drinking dairy milk? I have three teenagers. Should they not be drinking it either?

What we know today is that the pasteurization process works with the amount of virus going into the processing system. There have been a number of spot checks with commercial milk indicating that even though it looks like there may have been virus in that milk, the pasteurization process killed that virus. So in this point in time, the experience has shown at least testing the milk that is safe, safe to drink. And so anyone, that wants to drink dairy milk can drink dairy milk safely, I believe. What's important, though, to think about is it's a snapshot. So I want to encourage the FDA to continue testing the milk, not a snapshot. And it was safe two months ago. But as we have more, in fact at milk go into the process, we should continue to test that milk for its safety and provide that information to everyone so we can know exactly what our risk might be if it were to change over time. That goes back to transparency. And testing transparently, sharing that information in timely basis, will assure people that at least that food supply is safe.

Now, I just want to take a second here and underline that current testing shows that pasteurized milk is safe for people to consume. Rick's pretty clear on that. But like Rick also said, we need to keep testing and evolving our responses with what the science shows as we move forward at any given time. We just have a snapshot in time, so we got to continue asking questions. What about eating beef?

You know, at the experiments again, are not surprising that if you heat the virus to a certain level, you can kill the virus. And the USDA have done some experiments showing that if you cooked meat that contains infected influenza virus to 140 to 160 degrees, which is sort of medium to medium well or beyond, it does kill that virus. So I would encourage you to make sure that you are not eating, drinking raw milk, not eating raw meat, heating it to the right temperature when you do cook your hamburgers, should protect you from exposure to this virus.

Excuse my ignorance for a second here. You know, when I think about these viruses, I th ink, you know, you can inhale them. You can touch a surface and then touch your eyes or your nose or your mouth and get those mucous membranes. Can you eat the virus and become infected? I mean, I thought it would get churned up by your stomach acids and things.

You know, it's a little explored science, but we do know that people in Southeast Asia who have been infected with this virus could have been infected by consuming undercooked meat. In some cultures, they have a practice of drinking raw blood or raw blood soup. And and the virus has infected people from some of those practices. And so it's not surprising that it could infect a person that could be depending on the dose. And in addition, if they're drinking or eating and consuming something, maybe they're also touching it and touching their eyes, nose, and mouth. So it's really hard to distinguish those rules of inoculation. I will go back real quickly to the the meat question, though too. We know the end user, the consumer, if they cook their meat to the right temperature, it kills the virus. One of the things I'm concerned with is if there are infected cows going into a slaughterhouse, and those workers are touching that meat and raw meat were to be shipped from the slaughterhouse to restaurants or to stores, it is possible that there could be meat on a store shelf or in a restaurant, a fast food restaurant, particularly where some of the dairy cow meat goes to the fast food chain, and those workers could get infected if they were to touch that raw meat before they cooked it. So we have to do more testing. There's been very little testing of the meat on the farm and in the slaughterhouses. Again, there are barriers to doing that effectively now, and we need to increase the testing of the meat even before it gets on the store shelf.

Just a quick note here. The USDA says it is confident that the meat supply in the United States is safe and has a, quote, rigorous meat inspection process. As a medical reporter, I'm just wondering, Doctor Bright, what kind of advice you would give me. You know, I'm a doctor. I think you always want to find that inflection point between honesty and and being hopeful. You want to be hopeful, but honesty has to lead the way. How do you find that inflection point?

You know, I think it's really important that there's transparency in what we know. I think it's really important to get at the science as much as we can, and make sure that we are transparent about the science and that the transparency is timely and is as complete as possible. Would I get concerned about, that inflection point, is we're missing something and that we will get caught flat footed once again because we're not prepared. It's that complacency to think that we have it, that we are ready, that can cause the most harm. And right now, I understand our government, public health officials wanting to keep a calm because there really isn't a need right now for panic. However, at the same time, it's important that we're taking steps to be prepared, at risk, if this were to flash. And that means we have to take a hard look at what we prepared for in the past and ask ourselves those difficult questions. Is it the best we can do? Is it the best we can be prepared for a 21st century pandemic if we're still relying on technologies that were developed in the 1940s? And I say we're not prepared because we have the opportunity and the time now to to really modernize our preparedness posture and our technologies and tools. We also have the opportunity to educate people about the importance of the risk that they face today, and how that can change tomorrow, and how these tools can be really effective and helping them protect their family and save lives.

You know, something Rick said there really resonated with me. Most humans are not in imminent danger of contracting or dying of a bird flu infection at this moment. But at the same time, we don't want to be caught flat footed. We don't want to be complacent. I agree with that. And that's why I think it's important to keep talking about this evolving situation. What do we know about the science at any given time? What our leaders can do. What we can do. And that's not to scare anyone. That's to be proactive. That's to be prepared. I think if we learned anything from the Covid 19 pandemic, it's that paying attention matters. Doing our homework matters. And being honest matters. Next week on Chasing Life, I'm talking with Doctor Anthony Fauci about his new book, "On Call: A Doctor's Journey in Public Service." Chasing life is a production of CNN audio. Our podcast is produced by Eryn Mathewson, Jennifer Lai, Grace Walker and Jesse Remedios. Our senior producer and showrunner is Felicia Patinkin. Andrea Kane is our medical writer. Dan Dzula is our technical director. And the executive producer of CNN Audio is Steve Lickteig, with support from Jamus Andrest, Jon Dianora, Haley Thomas, Alex Manasseri, Robert Mathers, Leni Steinhardt, Nichole Pesaru, and Lisa Namerow.Special thanks to Ben Tinker, Amanda Sealy and Nadia Kounang of CNN Health and Katie Hinman.