A Spray in a Cow’s Nose Could Soon Protect It, and People, From Bird Flu

It was a first for cows last March when the U.S. Department of Agriculture announced the highly pathogenic avian flu virus H5N1 had been found in cattle. Since then, most of the 70 human cases of the disease in the U.S. have come from interaction with infected herds.

Now researchers from the University of Maryland and the USDA’s Agricultural Research Service (ARS) will work to head off infections in cows and people alike by developing a nasal vaccine to protect dairy cattle from bird flu with support from a $650,000 grant from the USDA’s National Institute of Food and Agriculture.

Preventing transmission of the disease from cows to people lessens the chances it will evolve into a human virus that can be passed from person to person, infectious disease experts say.

Xiaoping Zhu, professor and chair of the University of Maryland's Department of Veterinary Medicine, along with collaborator Wenbin Tuo of the ARS, plan to use the grant funding to adapt the nasal spray technology they originally developed for COVID-19 and human influenza. The vaccine could also potentially be used in humans, if necessary, they said.

“Preventing the initial infection and spread of H5N1 in cows means reducing exposure to the virus for other mammals, dairy workers and the general public,” Zhu said. “And that is critical to managing the spread of bird flu."

H5N1, the current strain of bird flu circulating around the U.S., is a moving target that not only kills wild birds and poultry, but has rapidly adapted to sicken other species beyond dairy cattle and humans to include domestic cats, foxes, raccoons and even seals.

Although only one person has died of the virus so far—a backyard chicken farmer in Louisiana—scientists are concerned that as more people are exposed to bird flu by animals, the more opportunities the virus has to mutate into an illness that could be transmitted between people, which is currently impossible.

In addition to being quick and easy to administer, Zhu and Tuo’s nasal vaccine has other advantages. While injection-based vaccines including mRNA vaccines trigger immune cells in the blood, which then attack a virus once an infection starts, nasal vaccines go to the source of respiratory infections.

Zhu’s and Tuo’s vaccine delivers a protein to the nasal passages that blocks viruses from infecting cells in the respiratory tract and prevents infections from even starting. That greatly reduces the likelihood of humans and other animals contracting the H5N1 virus from cows.