Yesterday, America had one of its worst days of bird flu to date. For starters, the CDC confirmed the country’s first severe case of human bird-flu infection. The patient, a Louisiana resident who is over the age of 65 and has underlying medical conditions, is in the hospital with severe respiratory illness and is in critical condition. This is the first time transmission has been traced back to exposure to sick and dead birds in backyard flocks. Meanwhile, California Governor Gavin Newsom declared a state of emergency after weeks of rising infections among dairy herds and people. In Los Angeles, public-health officials confirmed that two cats died after consuming raw milk that had been recalled due to a risk of bird-flu contamination.
Since March, the virus has spread among livestock and to the humans who handle them. The CDC has maintained that the public-health risk is low because no evidence has shown that the virus can spread among people, and illness in humans has mostly been mild. Of the 61 people who have so far fallen ill, the majority have recovered after experiencing eye infections and flu-like symptoms. But severe illness has always been a possibility—indeed, given how widely bird flu has spread among animals, it was arguably an inevitability.
The case in Louisiana reveals little new information about the virus: H5N1 has always had the capacity to make individuals very sick. The more birds, cows, and other animals exposed people to the virus, and the more people got sick, the greater the chance that one of those cases would look like this. That an infected teenager in British Columbia was hospitalized with respiratory distress last month only emphasized that not every human case would be mild. Now here we are, with a severe case in the United States a little over a month later.
Although worrying, the new case doesn’t change much about the predicted trajectory of bird flu. For months, experts have warned that bird flu would continue spreading among livestock and the people who work with them but that transmission among people was unlikely. And the CDC still says the public-health risk is low. “Everyday Americans should not be panicked by this news,” but they need to stay vigilant about bird flu, Peter Chin-Hong, an infectious-diseases expert at UC San Francisco, told me.
There are a few reasons the latest news shouldn’t cause alarm. The virus hasn’t found a way to efficiently infect humans; its receptors prefer animal hosts. This means the virus doesn’t enter the body at high levels. “It’s kind of forcing its entry using a jackhammer right now, so cases have generally been mild,” Chin-Hong told me. Higher levels of virus generally make people sicker. The Louisiana patient was infected with a strain of the virus related to the one that sickened the Canadian teen but different from the one spreading among dairy herds, poultry, and farmworkers. The mutations in this strain “represent the ability of the virus to cause serious disease, but these instances should be isolated in humans for the time being,” Chin-Hong said.
But just because America is in the same place of steady precarity that it has been in for months doesn’t mean that’s a good place to be in. As I wrote in September, we are in an awkward state of in-between, in which experts are on high alert for concerning mutations but the public has no reason to worry—yet. “Right now, I agree that the risk to the general public is low, but we know avian influenza mutates quickly,” Anne Rimoin, an epidemiology professor at UCLA, told me. The more transmissions among animals—in particular from birds to mammals—the more chances the virus has to mutate to become more threatening to the public. The longer the virus persists in the environment, “the greater potential to mutate, resort, and become more infectious and virulent to humans,” Maurice Pitesky, an animal-infectious-diseases expert at UC Davis, told me.
America is giving the virus a lot of chances to infect people. Although efforts to control the virus, such as regular testing of herds and bulk testing of raw milk, are under way, they have clearly not been enough. The spread of the virus geographically and across mammalian species is unprecedented, Pitesky said. He believes that more efforts should be directed toward shifting waterfowl—ducks, geese, and other wild birds responsible for spreading H5N1—away from commercial farms, where the virus is most likely to be transmitted to humans. A shot for bird flu exists, and experts have urged the government to vaccinate farmworkers. “Farmers need help,” Pitesky said. As of this month, the Biden administration has no plans to authorize a human vaccine, making it likely that that choice will fall under the purview of Donald Trump.
Just as a severe case in America was inevitable, continued mutation is a given too. At this rate, the virus will adapt to infect human hosts, cause more serious disease, and result in human-to-human transmission “at some point,” Chin-Hong said. Earlier this month, a study published in Science by researchers at the Scripps Research Institute showed that a single mutation in the virus strain spreading among dairy herds could switch its preference from bird to human receptors. “In nature, the occurrence of this single mutation could be an indicator of human pandemic risk,” the paper’s editor wrote.
Throughout the bird-flu outbreak, the main concern has been its potential to cause the next pandemic. That outcome is unlikely so long as bird flu remains unable to spread among people. Yet even if it does develop that ability, the world is more prepared for it than it was for COVID, which was caused by an unfamiliar virus. The H5N1 virus that causes bird flu has been known for nearly three decades; vaccine candidates, four influenza drugs, and a diagnostic test are already in existence. “We are not starting from scratch,” Chin-Hong said. Still, to not have to start at all would be preferable.
But right now, the future trajectory of bird flu points to the real possibility that the U.S. will have to weather the virus’s spread among people, with leadership that’s shown little interest in addressing it. Trump has not said anything about his plans, but he has picked Robert F. Kennedy, a vaccine skeptic and raw-milk enthusiast, to lead the country’s health agencies. In the absence of more stringent controls, the public can take steps to prevent the situation from worsening: avoiding raw milk and dead birds, for starters. Getting a regular flu shot decreases the chances of getting infected simultaneously with human and bird flu, which would create conditions for the viruses to combine into a virus that prefers humans. But what America needs is a plan, Pitesky said. The previous four flu pandemics had their origins in avian influenza. There is still time to prevent the next one.
