Researchers say cattle vaccination may reduce bird flu risk in herds and humans
According to research and commentary by Dr. Gregory Gray of the University of Texas Medical Branch (UTMB), published in The Journal of Infectious Diseases, vaccinating dairy cattle could help control the spread of H5N1 bird flu.
The spread of H5N1 bird flu in the United States is raising new concerns for livestock, public health, and the farm economy. What began in wildlife and poultry has now expanded into dairy cattle, prompting calls for stronger prevention strategies, including vaccination.
The outbreak began in 2022 in poultry flocks, leading to the loss of nearly 190 million birds. By 2024 it reached dairy cattle, affecting over 1,000 herds across 19 states and causing multi-billion-dollar losses.
Experts say the virus is evolving as it spreads across species, with each infection increasing chances of change and adaptation to mammals, including humans. Dairy cattle may act as an environment for viral adaptation.
"This virus has changed and now seems to have become entrenched or 'enzootic' in North American wildlife," said Dr. Gregory Gray, a professor in the Division of Infectious Disease and Department of Microbiology and Immunology at The University of Texas Medical Branch (UTMB).
"We used to think of H5N1 as a bird problem in Asia. Now it's clearly something bigger and here in our own backyard, and we need to respond accordingly. At first, people thought this was a one-off event, but it spread—and it's still spreading," said Gray.
So far, human infections in the United States remain limited, with around 71 confirmed cases and two deaths. However, experts note that farm workers and people consuming raw milk face higher exposure risk due to closer contact with infected animals.
Researchers suggest vaccinating dairy cattle could lower virus levels, slow spread between farms, and reduce transmission risk to humans and animals. Even if not perfect, vaccines may reduce disease and shedding.
Studies indicate cattle can develop strong immunity after infection, showing vaccines may work effectively. Early trials show promising immune responses, and existing dairy systems could support vaccination programs.
Countries such as Mexico and China have used poultry vaccination to control bird flu outbreaks. While not fully eliminating the virus, these programs reduced infection levels and economic losses significantly.
Experts emphasize that reducing virus circulation is essential. Lower infections in livestock reduce mutation chances and cross-species transmission, helping protect both food systems and public health in the long term.
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