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Should I be worried about bird flu? How dangerous is the new COVID variant? How does bird flu spread to humans? Is bird flu going to become a pandemic? What is HMPV?
AMA's Vice President of Science, Medicine and Public Health, Andrea Garcia, JD, MPH, discusses the "mystery virus" human metapneumovirus, that HMPV is not new, and shares trends in seasonal influenza and COVID-19 cases. Also covering the latest bird flu news of H5N9 on a California duck farm, as well as a raw pet food recall and the dangers of H5N1 for dogs and cats. AMA Chief Experience Officer Todd Unger hosts.
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Speaker
- Andrea Garcia, JD, MPH, vice president, science, medicine & public health, American Medical Association
Transcript
Garcia: That's the human metapneumovirus, or HMPV, for short. And some in the media have sensationalized it by calling it the mystery virus. But there's really no mystery to it, and it's not new by any stretch.
Unger: Hello and welcome to the AMA Update video and podcast. Today we have our weekly look at the headlines with the AMA's Vice President of Science, Medicine and Public Health, Andrea Garcia. I'm Todd Unger, AMA's chief experience officer. Welcome back, Andrea.
Garcia: Thanks, Todd. It's good to be here.
Unger: Well, we're looking at a lot of news out there about bird flu, so let's start there. A rare strain of the virus has been discovered on a California poultry farm. Andrea, tell us more about that and what it could mean.
Garcia: Yeah, Todd. There was an article in The Guardian earlier this week, and it noted that the World Organization for Animal Health reported the first outbreak of a rare bird flu in poultry, known as highly pathogenic avian influenza H5N9, and this has been detected on a duck farm in California. Authorities said the discovery of H5N9 came in addition to the detection of the more common H5N1 strain on that same farm in Merced County.
Almost 119,000 birds on the farm have been killed since early December. And according to the USDA, this is the first confirmed H5N9 case in poultry in the United States. The agency also said they're conducting comprehensive epidemiological investigations and enhanced surveillance and response.
The concern, once again, is whether or not this novel virus will cause human infections and become a pandemic subtype. That's not known yet and may actually not be known for some time. But it's certainly important to conduct further research on this.
Unger: Absolutely. And alongside this news, The New York Times also published an article that bird flu is entering a, quote, "new phase." What exactly does that mean?
Garcia: Well, Todd, I think it means that we really need to keep a close eye on this. And while it's impossible to predict the course of this virus, as you mentioned, The New York Times did lay out some potential scenarios based on what we know right now and how things are shifting, even ever so slightly. First, I think let's recap where we're at.
So the virus has infected more than 900 herds and 67 people in the U.S., killing one individual. The experts in The Times article said that while a human pandemic is not inevitable, some developments indicate that the possibility may no longer be quite so remote.
Unger: I guess that's really the bottom line here and all the discussions that we're having. Andrea, can you take us through some of those developments that are decreasing or, I guess, the odds that it's remote?
Garcia: Well, I think, first, there's the question of reinfection, which could dictate how this virus evolves over time. And like much of this, this isn't, at this point, 100% clear. The article gives one example where a few dairy herds in Idaho were affected this past spring, and then they displayed mild symptoms for a second time in November.
Now, the USDA has said that it does not see evidence of new infections or reinfections in previously affected herds but rather a lack of clearance of that original infection. However, outside experts have said that the trajectory of symptoms in Idaho herds suggests a second round of illness.
Unger: So why is it so important to make the distinction?
Garcia: Reinfection in and of itself wouldn't be particularly surprising, and symptoms could potentially be milder the second time around, which would be good. However, this suggests that the virus could circulate on farms indefinitely, and the longer it circulates, the more opportunities it has to evolve into a more dangerous form. Also, if the symptoms from reinfections are extremely mild, it would likely make that rapid detection difficult, if not impossible.
Unger: Now, Andrea, a second big question, of course, is about the virus's ability to spread between animals and humans. And I know that's a worry we've discussed a lot here before. Did that article or any other news sources address that concern?
Garcia: It did. And the worry here is that if bird flu circulates long enough, it could also eventually find that right combination of genetic mutations to make it easily transmissible among people. And adding to these concerns, in early December, scientists reported that, in a lab setting, a single mutation helped the virus infect human cells more efficiently.
If you recall, late last year, two people, a Canadian teen and a Louisiana resident, who was over the age of 65, became seriously ill with bird flu. And while the Canadian teen eventually recovered, the Louisiana man did not.
Unger: I remember you talking about that. Why are those particular cases so significant, then?
Garcia: Well, prior to those cases, people infected in the current outbreak didn't have severe symptoms. Both of those patients contracted a virus belonging to the D1.1 genotype that's been detected in wild birds and poultry. It is distinct from the one in dairy cattle. And in both individuals, that virus gained mutations during the course of infection that might allow it to better infect people.
Right now, the CDC still says the risk to the general public is low. But we also know how easily and quickly that could change. And given this, we really just cannot underestimate it.
Unger: Well, if history has taught us anything, it's that we can't underestimate any virus. And before we leave the topic of bird flu, we've seen some headlines about pet food. What does this have to do with bird flu, and why the concern now?
Garcia: Well, cats appear to be especially vulnerable to the H5N1 virus, and domesticated cats have actually died from bird flu in a number of states. In most cases, this was after consuming raw pet food or raw milk contaminated with the H5N1 virus. According to an article by NBC News, this has prompted the recall of at least one brand of pet food, as well as new federal guidelines on pet food quality.
This week, the FDA suggested that pet food manufacturers take precautions in their food safety plan, such as seeking ingredients from flocks or herbs that are healthy, and taking processing steps, such as heat treatment, that are capable of inactivating viruses. In its warning, the FDA said that H5N1 can be deadly to cats as well as dogs, so we're encouraging consumers to carefully consider the risk of this emerging pathogen before feeding their pets undercooked meat or an uncooked pet food product. We know that both the CDC and the American Veterinary Medical Association also discourage uncooked meat diets for companion animals.
Unger: Well, that's good to know, especially for us pet owners, including me. Andrea, let's turn our attention to something different now, and that's seasonal influenza. How are the numbers looking this week?
Garcia: Well, flu continues to be trending high across most states, and public health experts have expressed concern that, obviously, we could be missing H5N1 cases, as the most commonly used influenza tests do not distinguish between bird flu and seasonal flu. At CDC HAN, we discussed last week on a shortened timeline for subtyping all influenza A specimens among hospitalized patients does help to address this.
Also, in the rare case a person is simultaneously infected with seasonal flu and H5N1, the virus could, in theory, exchange genetic material to create a new virus that spreads more easily between humans. So while the chances of that happening are low, that's another thing to watch out for. But what really caught my attention this week was a Washington Post article with the headline, "COVID isn't as bad this winter. Flu is worse. Here's why."
Unger: That is an interesting quote. What did you learn?
Garcia: Well, it does feel like everyone is sick with everything right now. But the chances are it's not COVID. The COVID wave this winter has been less severe than previous years. We know that hospitalization rates are down, and wastewater surveillance levels are lower. Instead, we've seen a mix of other viruses this season, walking pneumonia, RSV, norovirus, bird flu, in addition to seasonal influenza, who's hospitalization rate is three times as high as COVID this season.
Unger: Wow. Andrea, did the article offer any insights as to why this is the case?
Garcia: Well, Todd, unlike flu and RSV, we know that COVID hangs around in the spring and the summer, and the COVID wave in the summer of 2024 was worse than in the summer of 2023. People who had COVID in the summer and were exposed to it again in recent weeks were less likely to become infected and spread the virus. I think vaccination also played a role, and while those numbers aren't where we'd hoped they'd be, more people got the updated COVID vaccine heading into this winter than last.
And now that practically everyone has some degree of immunity to COVID, the virus does have to evolve to bypass those antibodies. And that's just not happening like it once was. According to the article, the XEC variant, which now accounts for nearly half of new cases, is not substantially different than the KP and the FLiRT variants that drove our summer wave.
So I want to be clear. This doesn't mean that this will always be the case. More threatening variants could absolutely still emerge. But in the meantime, we know that it is other viruses that are really keeping physicians busy.
Unger: Speaking of other viruses, before we wrap up, Andrea, I've been hearing about another virus in China that apparently has now made its way here to the U.S. What is that virus? And is there cause for concern?
Garcia: Well, Todd, that's the human metapneumovirus, or HMPV for short. And some in the media have sensationalized it by calling it, "the mystery virus."
But there's really no mystery to it, and it's not new by any stretch. According to a New York Times article that ran earlier this month, HMPV has circulated in humans for decades. It's a respiratory illness and is so common that most people will be infected as children and experience several infections in their lifetimes.
In countries with months of cold weather, HMPV can have an annual season, much like flu. And then in hotter climates, it circulates at lower levels all year long. In higher-income countries, the virus is rarely fatal. In lower-income countries, with weaker health systems and poorer surveillance, deaths are more common.
Unger: Andrea, if this is a virus that's been circulating for decades, why haven't we heard of this or heard a lot about it lately?
Garcia: Well, Todd, it certainly doesn't have the same name recognition because it's rarely discussed by name. According to a physician in The Times article, the clinical features are difficult to distinguish from other viral illnesses, and physicians don't routinely test for HMPV.
Most infections typically go unrecognized and are chalked up to whatever respiratory thing happens to be going around. These symptoms include cough, fever, nasal congestion and wheezing. Most infections are mild, but severe cases can result in bronchitis or pneumonia, particularly among infants, older adults and people who are immunocompromised.
Unger: So, Andrea, why is it making news now?
Garcia: Well, Todd, cases have been increasing, and Chinese authorities have said that HMPV cases could spike even more during the Lunar New Year holiday, which we know is at the end of this month. We also know from recent articles that levels are currently high in the UK, which is often indicative of what we can expect here.
According to an article last updated on Sunday, Britain is on high alert as cases have surged, prompting both health warning and calls for masking. A report from mid-January suggests that HMPV is already currently increasing in some parts of the United States, including in Kansas, Iowa, Missouri and Nebraska. So, it's something to keep an eye on but certainly nothing to panic about.
Unger: All right, Andrea. Well, thank you so much for the update. And that wraps up this week's episode. As always, thanks for being here and keeping us informed.
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Disclaimer: The viewpoints expressed in this podcast are those of the participants and/or do not necessarily reflect the views and policies of the AMA.