How Bird Flu Is Shaping People’s Lives

A conversation with Katherine J. Wu about the disease sweeping through animals and raising food-safety questions

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For the past couple of years, scientists have watched with growing concern as a massive outbreak of avian flu, also known as H5N1 bird flu, has swept through bird populations. Recently in the U.S., a farm worker and some cattle herds have been infected. I spoke with my colleague Katherine J. Wu, who covered the virus’s spread in North America, about the risk of human infection and how, for animals, this has already been “a pandemic many times over.”

Katherine J. Wu: When we’re considering the toll on nonhuman animals, this is the largest, most deadly H5N1 outbreak that has been recorded in North America. It has been unfolding slowly for about two and a half years now, but it’s become a gargantuan wave at this point.

Katherine: I’m medium concerned—and I have been medium concerned for a couple of years now. It’s difficult to gauge the amount of alarm to feel, because it’s so unprecedented. Still, most H5N1 outbreaks in the past have totally fizzled without much consequence, especially in this part of the world.

I am worried because so many species have been getting sick. A huge number of wild birds have been infected, including species that haven’t been affected in the past. And we’ve seen these massive outbreaks in domesticated chickens, which are packed together in farms.

Avian flu is known to be a bird problem. Beyond that, we’ve been seeing these outbreaks in mammals for a couple of years now, which is more concerning because, of course, we are also mammals. Humans seem to be potentially susceptible to infection, but at the same time, it would take quite a lot for this to become another big human-flu pandemic.

Katherine: People should be vigilant and paying attention to the news. But right now, as you and I are talking, there is still not a huge risk to people. You don’t get a pandemic unless you have a pathogen that spreads very, very easily among people, and there’s no evidence so far that this virus has mutated to that point.

There have been some human cases globally so far, but it’s a very small number. They seem to have been cases where someone was highly exposed to the virus in domesticated animals. People got sick, but they didn’t pass it to someone else.

I’m definitely not saying that person-to-person transmission can’t happen eventually, but there’s a pretty big chasm between someone getting infected and someone being able to efficiently pass the virus on. It is concerning that we continue to see more mammal species affected by H5N1, including species that have a lot of close contact with humans. But this is not a five-alarm fire so far.

Katherine: The virus has already affected our lives. Egg prices went completely bonkers in 2022 and early 2023, and over the course of this outbreak, more than 90 million domestic poultry have died. It’s not that all of those birds got sick—when this virus breaks out on chicken farms, it’s generally considered good practice to cull the chickens to halt the spread. Still, when you have that many chickens dying, egg prices are going to go up.

We’re probably not on track to see that with cows anytime soon. Even though this virus has now been detected in dairy cows, they aren’t getting wildly sick, and transmission doesn’t seem as efficient. I don’t think we’re going to be in a situation where we’re killing all of our dairy cows and no one can get milk.

Lora: The FDA announced yesterday that genetic evidence of this bird-flu virus had been found in samples of pasteurized milk. Is it still safe to drink milk?

Katherine: So far, the answer is: generally, yes, if it’s been pasteurized. Pasteurization is a process by which milk is treated with heat so that it will kill a whole bunch of pathogens, including bacteria and viruses, and H5N1 is thought to be vulnerable to this. Also, researchers have been working to test cows so they can figure out which ones are sick. Only milk from healthy cows is authorized to enter the general food supply, though the trick will be finding all the cows that are actually infected. For now, the main ways that this virus will affect us will be indirect.

Katherine: For the animal world, this has already been a “pandemic” many times over. It has been truly devastating in that respect. So many wild birds, sea lions, seals, and other creatures have died, and it’s difficult to see how people can effectively intervene out in nature. There have been very few cases in which endangered animals have received vaccines because there’s a real possibility that their populations could be 100 percent wiped out by this virus.

For most other animals in the wild, there’s not a lot that can be done, except for people to pay attention to where the virus is spreading. The hope is that most animal populations will be resilient enough to get through this and develop some form of immunity.

Lora: Responses to COVID became very politicized. How might the aftermath of those mitigation measures shape how people respond to this virus, especially if it becomes a greater threat to humans?

Katherine: We’re so fresh off the worst days of COVID that if people were asked to buckle down or get a new vaccine, I suspect that a lot of them would be like, Not again. There is still a lot of mitigation fatigue, and many people are sick of thinking about respiratory viruses and taking measures to prevent outbreaks. And, certainly, people have lost a lot of trust in public health over the past four years.

That said, H5N1 is still a flu, and people are familiar with that type of virus. We have a long history of using flu vaccines, and the government has experience making a pandemic vaccine, keeping that stockpile, and getting it out to the public. That gives me hope that at least some people will be amenable to taking the necessary preventative measures, so any potential bird-flu outbreak among humans would not turn into COVID 2.0.

Inflation, finally, has cooled off. Prices have increased 2.5 percent over the past year, down from increases as high as 7 percent during the early pandemic. Rents are high but stabilizing. The cost of groceries is ticking up, not surging, and some goods, such as eggs, are actually getting cheaper. But American consumers are still stretching to afford one big-ticket item: their cars.

The painful cost of vehicle ownership doesn’t just reflect strong demand driven by low unemployment, pandemic-related supply-chain weirdness, and high interest rates. It reflects how awful cars are for American households and American society as a whole.