Since bird flu was first discovered in U.S. cattle last year, the virus has spread to more than 1,000 herds across the country. A new vaccine for cattle has performed well in early tests, raising hopes that it could protect livestock and help prevent an outbreak in humans.
New research, which has not yet been peer-reviewed, found that calves administered an experimental bird flu vaccine made protective antibodies. When later fed milk from infected cattle, the vaccinated calves showed lower levels of the virus than unvaccinated calves.
“I don’t think that cattle vaccines on their own are sort of a silver bullet,” said Richard Webby, an infectious disease expert affiliated with the World Health Organization, who was not involved in the new research. “But we have to do something different because what we’re doing now is clearly not working,” he told Nature.
Since 2024, U.S. officials have recorded more than 60 cases of the virus in humans, including the first U.S. death, in January. Scott Hensley of the University of Pennsylvania, coauthor of the new research, told Nature that the virus poses a “real pandemic threat.” Globally, roughly half of people infected with bird flu have died.
The U.S. Department of Agriculture has cleared at least seven experimental livestock vaccines for trials this year, and in February it conditionally approved a vaccine for chickens. Since 2022, bird flu has killed more than 170 million farmed birds in the U.S. alone.
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