The Food and Drug Administration last week released some alarming results about the bird flu epidemic spreading among dairy cows. It found that 1 in 5 samples taken from the commercial milk supply contained influenza viral fragments.
Opinion | The Checkup With Dr. Wen: Answering reader questions about bird flu
Opinion piece by Dr. Leana Wen.
Yes, it’s still safe to drink milk even if avian flu virus fragments are in the milk supply.
While this suggests that bird flu is far more widespread among cattle than previously thought, there is no reason to stop consuming milk. My recommendations from two weeks ago have not changed: Most Americans should not worry about the risk of bird flu to their health and do not need to change their behaviors at this time.
Many readers had questions specifically about the risks of drinking milk. Anne from Virginia wrote that she has three young children. “I am not worried about myself so much, but I worry about my kids. They drink milk during breakfast and with dinner. Should I switch them to almond or soy milk?”
Nancy from Pennsylvania similarly wants to know if other dairy projects such as cheese and yogurt are safe. “I include dairy in my diet to keep bones strong. Do you recommend using other calcium sources instead?”
I also drink a large glass of milk every morning, and both my kids have at least two glasses a day. I am not changing our milk consumption and do not advise Anne or Nancy to do so, either.
That’s because commercially available milk is pasteurized. This is a process in which the milk is heated to a high temperature for a set time to kill bacteria and viruses. Multiple studies have shown that it is effective in killing influenza viruses. Preliminary results confirm that pasteurization inactivates the avian H5N1 strains driving the outbreak, and the FDA has affirmed that the “commercial milk supply is safe.”
This means that cheese and yogurt made from pasteurized milk are safe, too. People should refrain from consuming unpasteurized milk products, which can carry other microbes that cause foodborne illnesses, such as salmonella, E. coli and listeria. It is also not known whether drinking raw milk could transmit avian flu.
“What about infant formula?” Darcy from Michigan inquired. “A lot of infant formula uses cow’s milk. Are we going to have another infant formula shortage?”
The FDA has tested several samples of retail powdered infant formula and found no avian flu virus fragments. Even if fragments are found in the future, the guidance will probably be unchanged, as commercially sold formula also goes through strict sterilization procedures.
As a result, I don’t think we will see an infant formula shortage due to avian flu, though, as my colleague Alyssa Rosenberg reminds us, there are steps lawmakers should take to ensure that the crisis that occurred in 2022 does not repeat itself.
Of course, just because milk remains safe to drink doesn’t mean avian flu isn’t a potential threat to human health. I was honored to learn historian John M. Barry, author of the seminal book on the 1918 influenza pandemic, is a Checkup reader. He emailed me to express his worries, and I took him up on the offer to speak by phone.
“The question is, are we in the early stages of watching the evolution of this virus toward something that will become respiratory and spread through the aerosols between mammals and humans?” he said. “It’s too early to say that that’s happening, but there are some things that are disconcerting.”
Indeed, while the spread of H5N1 from birds to mammals has long been documented, we have not previously observed this scale of outbreak among mammals. Health officials do not know how cows are spreading the virus to one another and whether there could be asymptomatic transmission. And there are concerns that some farms might not cooperate with federal guidance to test and isolate affected cows.
Barry reminds us that “virtually nothing” is known about how the 1918 influenza jumped species or how long these evolutionary changes took to occur. And even if we did know these details, it would be unwise to expect avian flu to follow the same playbook.
All that said, we should keep in mind that there are not yet any instances of human-to-human transmission during this avian flu outbreak. And I remain reassured that federal health officials have a plan for manufacturing and distributing treatment and vaccines, should bird flu become the next pandemic.