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This year, human cases of H5N1 bird flu ramped up in the U.S., particularly after the virus made its way into dairy cattle herds. In this report, experts share their concerns about what may happen with H5N1 in the year ahead.

The Biden administration's response to H5N1 avian influenza, or bird flu, has been lackluster, and infectious disease experts said they are on edge about how the response to the virus will be handled in a second Trump administration.

"I don't think H5N1 has been managed very well in the Biden-Harris administration, and probably will only get worse during the Trump administration, if we can judge by some of their COVID policies, as well as some of the people who are going to be put in charge of agencies," Amesh Adalja, MD, of the Johns Hopkins Center for Health Security in Baltimore, told 名媛直播.

James Lawler, MD, MPH, of the University of Nebraska Medical Center's Global Center for Health Security in Omaha, agreed that the current response "has been incredibly anemic."

"Even without a change of administration we should be concerned," he said. "In September we were still in the 20s in terms of human cases, and now we're in the 60s. That doesn't mean we're on an inevitable course to end up with a pandemic, but it means that the virus is starting to find its way into humans and potentially tune itself to being a human pathogen."

As of December 30, there were 66 confirmed cases of H5N1 avian influenza infection in humans in 2024, with about half in patients in California, . The U.S. reported its first severe case of H5N1 requiring hospitalization on December 13, in a patient in Louisiana who had exposure to sick birds in a backyard flock.

Many of the cases either had exposure to dairy cattle (40) or poultry farms and culling operations (23). The source of exposure was reported as "unknown" in two patients, including a patient in Missouri who had been hospitalized but did not have severe illness.

So in 2025, when will it be time to become more worried about H5N1? "If we start seeing lots of cases outside of agricultural workers, we should be really concerned," Lawler said. "That will be a trigger point and a warning that we have potentially entered a new phase."

Adalja said the U.S. Department of Agriculture's (USDA) comes much too late in the game, but will be helpful in finally showing how widespread the problem is.

"As it comes online, we'll see more states than are on the test positive," he told 名媛直播. "We'll find this is much more widespread in dairy cattle. And I think we'll find more human cases. The number is in the 60s and everyone knows that's an undercount."

Adalja noted that there's a case to be made that dairy farm workers, poultry workers, and even veterinarians should be offered an H5N1 vaccine. However, Lawler said that the stockpiled and approved H5N1 vaccines in the U.S. may not be the best matched to the current strains circulating in livestock.

"We don't know whether they'll work in people," he added. "It's a point of debate among immunologists as to how well matched the stockpile is, because they were made for viruses that were floating around years ago."

Adalja thinks it's likely that the B3.13 genotype of H5N1 will become endemic in dairy cattle, but federal officials have said that's not the case just yet.

"We know we can effectively eliminate the disease from herds even in the absence of a vaccine," Eric Deeble, deputy under secretary for marketing and regulatory programs at the USDA, said during a press briefing on December 18. "We are quite confident we can continue those efforts to eliminate the virus from the national herd."

He added that a bovine H5N1 vaccine program is under investigation, with seven vaccine field safety trials approved by the agency. It's not possible to predict how long development of a bovine vaccine will take, he noted.

"A vaccine would be helpful [in eliminating the virus from the herd], and it's part of the reason we're pursuing it with a great deal of vigor," Deeble said. "But no, I don't think we're considering B3.13 to be endemic in the herd, and I think we can eliminate it."

Adalja cautioned that if the virus becomes endemic in the herd, that creates "a new occupational risk for dairy cattle workers, decreased milk production for dairy cows, and eventually you'll have people shunning U.S. dairy products."

"I think people only think about the short run and that's what's happening with the shortsighted policies from the agricultural sector and the farmers themselves," Adalja said. "I don't expect that thinking will get better."

"It's been a flawed response from the very beginning," he added. "It would be good if the Trump administration took this threat seriously and made an Operation Warp Speed type of project to develop better countermeasures, better vaccines, better diagnostic tests for this."

"Maybe people were lulled into complacency by the fact that we had not seen severe infections in humans before, but we've now had a few people who've ended up in a hospital with this infection," Lawler said. "It just reminds us that this is a dangerous virus."

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