CNN
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The US has not learned lessons from the Covid-19 pandemic that it could use to contain the threat of pathogens such as H5N1 bird flu, which continue to show signs of their own pandemic potential, health experts told CNN on Friday.

“We’re kind of in the dark about how widespread this is from a zoonotic standpoint, from an animal-to-human standpoint,” Dr. Deborah Birx, the White House coronavirus response coordinator under President Donald Trump, on “CNN.” Newsroom” with Pamela Brown.

Birx called for far more widespread testing of farmworkers, who make up the majority of identified cases in the U.S., noting that the country is heading into an even higher-risk period as the seasonal flu becomes more widespread. That raises the possibility that a person could become infected with both the seasonal flu and H5N1 and the viruses could swap gene segments, Birx said, giving the bird flu virus more tools to better infect people, a phenomenon known as reassortment .

A spokesperson for the U.S. Centers for Disease Control and Prevention pushed back Friday, telling CNN in a statement that the “comments on avian influenza (H5N1) testing are outdated, misleading and inaccurate.”

“Despite data suggesting that asymptomatic infections are rare, the CDC changed its recommendations back in November to expand the testing network to include testing of asymptomatic people at high risk for avian influenza, and directed hospitals over the summer to continue doing so “This is part of the nationwide surveillance effort and not the normal limitation of surveillance at the end of the flu season,” the spokesman said.

“The result: More than 70,000 samples were examined for novel flu viruses; “More than 10,000 people exposed to bird flu were monitored for symptoms and 540 people were specifically tested for H5N1,” the spokesperson continued. “In addition, CDC partnerships with commercial laboratories mean that H5N1 testing is now available in doctor’s offices across the country, significantly increasing testing capacity.”

The CDC added that a seasonal influenza vaccination campaign is underway for farmworkers in states with infected herds to protect them from seasonal influenza and reduce the likelihood of reinfection with the H5N1 virus.

The agency also said there is currently no human-to-human transmission of H5N1. However, there is still a risk that the virus will evolve in a way that makes it easier to infect people.

The CDC reported Thursday that a genetic analysis of samples from the Louisiana patient who was recently hospitalized with the country’s first severe case of H5N1 found that the virus likely mutated in the patient and may be more easily transmitted to humans be transferable. However, there is no evidence that the virus was transmitted to anyone else.

The patient was likely infected after coming into contact with sick and dead birds in a backyard flock, the CDC said earlier this month. In its analysis Thursday, the agency said the mutations it identified in samples taken during the patient’s hospitalization were not found in the birds, suggesting they are not part of the virus widespread in wild animals .

The mutations, similar to those seen in a hospital patient in British Columbia, Canada, could make it easier for the virus to bind to cell receptors in people’s upper respiratory tract, the CDC said.

“The observed changes were likely caused by the replication of this virus in patients with advanced disease and were not primarily transmitted at the time of infection,” the agency said. “Although concerning and a reminder that A(H5N1) viruses can develop changes in the clinical course of infection in humans, these changes would be more concerning if they occurred in animal hosts or in early stages of infection… when these changes would be more likely .” to facilitate spread to close contacts.”

The CDC stressed that the risk to the general public has not changed and remains low, but said the detection of the genetic mutations “recognizes the importance of continued genomic surveillance in humans and animals to contain outbreaks of avian influenza A(H5). in dairy cattle and other animals.” Poultry and preventive measures in people exposed to infected animals or environments.”

The analysis found no changes related to markers that could mean antiviral drugs would not work as well against the virus, the CDC added, noting that the samples were closely related to strains that could be used to make vaccines if needed could be used.

The CDC noted that the sequences also showed no changes in genes associated with mammalian adaptation. The patient was infected with a strain called D1.1, which is closely related to viruses circulating in wild birds and poultry in the United States. Another strain called B3.13 has spread widely in dairy cows and has not been found to cause serious human disease in the United States

“While this sounds like good news, the H5N1 situation remains dire,” wrote Dr. Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan in Canada, on Bluesky on Thursday.

“There has been an explosion in human cases,” she said. “We don’t know what combination of mutations would result in a pandemic H5N1 virus… but the more people are infected, the greater the chance of creating a pandemic virus.”

The CDC has confirmed 65 human cases of H5N1 avian flu in 2024. Of these, 39 were related to dairy herds and 23 to poultry farms and culling operations. In two cases the source of exposure is unknown. The serious case in Louisiana is the only one linked to backyard herds.

Dr. Paul Offit, a vaccine scientist at Children’s Hospital of Philadelphia, noted that the CDC said the mutations “may” allow the virus to better bind to cell receptors in people’s upper respiratory tract, but that is not clearly the case.

“I would like to see clear evidence … that it binds well,” Offit told CNN on Friday. “That hasn’t happened yet.”

“And more importantly,” Offit added, “there is not the clinical relevance that you see in person-to-person transmission.”

But the spread among animals such as cows has some health experts on high alert. Since the virus was first detected in cattle in March, outbreaks have been detected in herds in 16 states.

This month, the U.S. Department of Agriculture launched a national milk testing program to track the spread of the virus through dairy cows, and the agency has so far turned on 13 states that account for nearly half of the country’s milk production.

The program requires raw milk samples to be collected prior to the pasteurization process and submitted to the USDA for testing.

Government authorities say pasteurization inactivates the virus and makes pasteurized milk drinkable. The Food and Drug Administration and other health authorities are warning consumers not to drink raw milk not only because of the danger of H5N1, but also because of the danger of E. coli, salmonella and listeria.

However, the fact that the H5N1 virus has already spread so quickly among cattle suggests that “the USDA has essentially dropped the ball completely,” said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, in an interview with CNN on Friday. “I think it was done out of fear to protect the industry. And they thought it was going to burn out, but it didn’t.”

Osterholm also said the U.S. and others around the world should have done more to examine lessons from the Covid-19 pandemic and accelerate work to improve flu vaccines.

And he noted, “The new administration comes in and says they’re going to do infectious disease research for the next eight years,” referring to comments made by President Trump’s nominee to lead the U.S. Department of Health and Human Services , Robert F. Kennedy, Jr.

Osterholm said his risk assessment for H5N1 has not changed based on this week’s Louisiana results, but he is always concerned about the threat of pathogens such as the bird flu virus.

“The pandemic clock is ticking,” Osterholm said. “We just don’t know what time it is.”