by When Bird Flu first struck siry cattle a year ago, it seemed possible that it might affect a few isolated herds and disappear as quickly as it appeared. Instead, the virus has infected more than 900 herds and dozens of people, killing one, and the outbreak shows no signs of abating.
A pandemic is not inevitable even now, more than a dozen experts said in interviews. But a series of developments in recent weeks indicate the possibility is no longer remote.
Toothless guidelines, insufficient testing and long delays in releasing data – echoing the missteps during the Covid-19 pandemic – have squandered opportunities to contain the outbreak, the experts said.
In one example emblematic of the disorder, a pair of Idaho dairy herds infected in the spring showed mild symptoms a second time in late fall, the New York Times has learned. In mid-January, the Department of Agriculture said no new infections had been identified in Idaho herds since October. But state officials publicly discussed milder cases in November.
That a second bout of infections would cause milder symptoms in livestock is not surprising, experts said, and could be welcome news for farmers. But reinfections suggest that the virus, called H5N1, could circulate indefinitely on farms, setting it up to evolve into a more dangerous form—a “high-risk” scenario, said Louise Moncla, an evolutionary biologist at the University of Pennsylvania.
“You could easily end up with endemic circulating H5 in dairy herds with no symptoms, obscuring quick or easy detection,” said Dr. Moncla.
It’s impossible to predict whether the virus will develop the ability to spread among people, let alone when they and others said. But the worry is that if bird flu finds the right combination of genetic mutations, the outbreak could quickly escalate.
“I’m still not pack-my-bags-and-head-to-the-hills worried, but there have been more signs in the last four to six weeks that this virus has the capacity” to cause a pandemic , said Richard Webby, an influenza expert at St. Jude Children’s Research Hospital.
Federal officials have also subtly changed their tone when discussing the outbreak, now emphasizing how quickly the situation can change.
For the general public, H5N1 is “a low risk, relative to the other risks they face today,” said Dr. Nirav Shah, chief adviser to the Centers for Disease Control and Prevention. But “100 percent, that could change,” he said. “This is a dangerous virus.”
Health experts emphasize that there are precautions Americans can take: don’t touch sick or dead birds or other animals; Get tested if you have flulike symptoms; Do not consume raw milk or meat, or feed them to your pets.
If a larger outbreak were to erupt, the Federal Vaccine Stockpile has a few million doses, although that vaccine may need to be updated first to match the evolved form of the virus. In both cases, officials would have to scramble to produce enough for the population.
The CDC recommends treatment with the antiviral Tamiflu, but studies have shown that the drug does very little to alleviate the disease.
Underscoring concerns among many experts, Robert F. Kennedy Jr., who would lead the federal health department if confirmed, has been a vocal critic of Covid vaccines and has said the bird flu vaccines “appear to be dangerous.”
Even if the second Trump administration embraces vaccine development, as the first did as Covid descended, it is unclear how many Americans would roll up their sleeves for the shots. Influenza usually affects children and older adults, and pandemic influenza sometimes hits young adults the hardest. But the distrust created during COVID-19 may cause Americans to shy away from precautions, at least initially.
An evolving threat
Unlike the coronavirus, which caused damage with its sudden arrival, flu viruses usually start in a specific species or in certain geographic areas.
When H5N1 emerged in East Asia nearly three decades ago, sick birds usually fell ill. In the years that followed, it infected at least 940 people, almost all of whom had close contact with infected birds; About half of those people died.
But since January 2022, when the virus was detected in wild waterfowl in the United States, it has affected more than 136 million commercial, backyard and wild birds, helping to drive egg prices. It has also struck dozens of mammals, including cats, both wild and domestic, raccoons, bears and sea lions.
For at least a year, H5N1 has been infecting dairy cattle, which were not known to be susceptible to this type of influenza. In some cows it has had lasting effects, reducing milk production and increasing the chance of spontaneous abortions.
And in 2024, the virus infected 67 Americans, compared to just one in previous years, in 2022. The sources of these infections are not all known; One person could have transmitted the virus to someone in their household.
Many of these developments are classic steps toward a pandemic, said Dr. James Lawler, a director of the Global Center for Health Security at the University of Nebraska. But, he noted, “where those were really supposed to trigger accelerated and enhanced actions at the federal, state and local levels, we’ve just kind of been picked up when each milestone has passed.”
Infections in Dairy herds, which first emerged in Texas, appeared to be declining last summer. But in late August, California announced its first case. The state’s numbers soon rose sharply, causing Gov. Gavin Newsom declares a public health emergency in December.
“That was kind of a flag for me, like, ‘OK, this hasn’t gone away,'” said Dr. Manisha Juthani, commissioner of the Connecticut Department of Public Health. “Over the last few months, it’s felt like the pace has picked up ,” she said.
Several other recent events have raised the level of alarm among experts. In early December, scientists reported that in a laboratory setting, a single mutation helped the virus infect human cells more efficiently.
And late last year, two people, a 13-year-old Canadian girl and a Louisiana resident over 65, became seriously ill; Previously, most people infected with H5N1 had not experienced serious symptoms. The Louisiana patient, who had health problems and cared for sick and dying birds, died in early January.
The girl was placed on life support due to organ failure, but eventually recovered. Scientists still don’t know how she became infected; Her only risk factor was obesity.
Both patients had contracted a new version of the virus that differs from that found in dairy cattle and is now widespread in birds. In both individuals, the virus acquired mutations during infection that could make it better at infecting people.
“We’re clearly now getting new viruses forming in the Wild Bird Reservoir,” said Dr. Moncla. “It has become a challenge to get a handle on all the different threats.”
Some experts see it as particularly concerning that the virus appears to be present in food sources such as raw milk and raw pet food. Domesticated cats have died in numerous states, prompting a recall of at least one brand of pet food and new federal guidelines on pet food quality.
“The raw pet food thing to me is, I think, pretty alarming,” said Dr. Jeanne Marrazzo, director of the National Institute of Allergy and Infectious Diseases.
Pasteurization kills a live virus, just like cooking meat at high temperatures. Still, neither procedure is perfect, noted Dr. Marrazzo notes: “There is no way you can monitor production and sterilization in a way that will ensure that 100 percent of the time that food supply will be safe.”
A flawed response
In the year since the outbreak began, federal officials have announced other measures to prevent or prepare for a pandemic. But each is deeply flawed, experts said.
The U.S. Department of Agriculture was slow to test H5N1 vaccines for cows, leaving interested companies in Limbo. Dr. Marrazzo said the department had released genetic information from virus samples but did not say where or when they were collected – details that would help scientists track the evolution of the virus.
It is also unclear how many herds are being reinfected or have been battling months of infections. In Idaho, some herds that were infected in the spring appeared to have milder symptoms again in November.
“From the data we have to date, we see no evidence of new infections or reinfections in previously affected herds, but rather a lack of clearance of the original infection,” a USDA spokesperson said in an emailed response. But outside experts said the trajectory of symptoms suggested a second round of illness.
The USDA’s program to test bulk milk began in December — nearly a year after the outbreak began — and still doesn’t include Idaho. Compelling private companies can help the program move faster.
Ginkgo Bioworks, a company that worked with federal agencies during the Covid pandemic, is already assessing about half of the country’s commercial milk supply for bacteria, antibiotics and other substances.
Adding H5N1 to the list would be simple, so “why not just add assays to this infrastructure we already have?” said Matt McKnight, a manager in the company’s biosecurity division.
Earlier this month, the Biden administration announced $306 million in new funding, about a third of it for surveillance, testing and outreach to farmworkers.
But farmworkers in some places like the Texas Panhandle are still unaware of what bird flu is, how it spreads and why it should matter, said Bethany Alcauter, director of research and public health programs at the National Center for Farmworker Health.
As a result, she said, many workers are still not using protective equipment, including in dairy parlors where the virus is believed to be spreading.
Human testing has been voluntary and infections have been missed. Few farmworkers have chosen to be tested, fearing immigration officials or their own employers.
“If you’re not looking for it, you’re not going to find it, right?” said Dr. Deborah Birx, who served as White House Coronavirus Response Coordinator under President Trump. “This is not about lockdowns or restricting activities. It’s about protecting the individual American by empowering them with the information. “
