Cases of bird flu in cattle and humans are on the rise; researchers disagree on vaccinations for farmworkers

Dairy cows or milk could infect humans
with bird flu. (Photo by A. Kipp, Unsplash)

As cases of bird flu increase in cattle, some experts believe the United States should follow Finland's example and offer vaccinations to workers who are likely to be exposed. "Veterinarians and researchers have taken note of Finland’s move to vaccinate farmworkers at risk of infection. They wonder why their government doesn’t do the same," report Amy Maxmen and Arthur Allen of KFF Health News.

Many farmworkers may handle infected birds or raw milk products, which could leave them vulnerable to catching the virus. Kay Russo, a livestock and poultry veterinarian in Fort Collins, Colorado, told KFF Health News, "Farmworkers, veterinarians, and producers are handling large volumes of milk that can contain high levels of bird flu virus. . . . If a vaccine seems to provide some immunity, I think it should be offered to them.”

Testing results from Colorado may support the move to vaccinate workers who could be in contact with cows, raw cow milk or chickens. Amy Maxmen of KFF Health News reports, "Five people who work at a poultry farm in northeastern Colorado have tested positive for the bird flu, the Colorado public health department reported July 14. (One of the cases awaits confirmation by the federal Centers for Disease Control and Prevention.) This brings the known number of U.S. cases to nine."

Extreme heat may have played a role in the virus' spread in Colorado because farmworkers' protective gear, such as goggles and masks, makes the work even hotter. "Jennifer Nuzzo, director of the Pandemic Center at Brown University, posted on X, 'You don’t send farm workers in to cull H5N1 infected birds without goggles and masks. Period,' Maxmen reports. "If it’s too hot to wear those protections, it’s too hot to cull. We need vaccines to be made available to farm workers. We have to stop gambling with peoples’ lives.'"

So far the CDC has remained reluctant to pursue bird flu vaccinations. "Some researchers side with the CDC recommending against vaccination for now," Maxmen and Allen write. "There’s no evidence that this year’s bird flu virus spreads between people or causes serious disease in humans. And it’s unclear how well the available vaccine would prevent either scenario. . . . In considering vaccines, the agency takes a cue from a 1976 outbreak of the swine flu."

So far, it has been difficult to gauge how many people have been infected with H5N1, but some researchers in Michigan are working on testing for it. "To understand whether cases are going undetected, researchers have sent the CDC blood samples from workers on dairy farms," Maxmen reports.