virus this year, with most cases linked to close contact with infected cows or chickens. While this suggests that the virus is primarily spreading through animal-to-human transmission, a new study published on December 5 in the journal Science has raised concerns about the virus’s potential to evolve into a more serious threat.
The study highlights that the H5N1 strain currently circulating among U.S. cows is just one mutation away from being able to bind to human cells, a key step for human-to-human transmission. James Paulson, a professor of molecular medicine at Scripps Research, co-authored the study and explained that such a mutation could be the “prerequisite for transmission among humans.”
Currently, the virus primarily infects birds and cows, sickening millions of animals across the U.S. dairy industry. While human cases are rare, they have largely been confined to farmworkers with close exposure to infected animals. Despite the virus’s limited ability to infect humans, experts say that these rare cases underscore the potential risks, especially if the virus mutates in a way that allows it to more easily infect humans.
According to Troy Sutton, assistant professor of veterinary and biomedical sciences at Penn State University, the virus doesn’t grow well in the human nose and throat, which limits its ability to spread through coughing or sneezing. However, Sutton warns that if the virus evolves to spread more easily between people, it could lead to a pandemic.
Paulson’s team conducted laboratory experiments on a synthetic gene from the circulating bovine H5N1 strain. Their results were surprising, showing that a single mutation in the virus could be enough for it to bind to human cells. “The emergence of a bovine H5N1 virus capable of recognizing human receptors may be closer than previously thought,” said Yoshihiro Kawaoka, a professor at the University of Wisconsin-Madison, who was not involved in the study.
While public health officials emphasize that the virus is not yet spreading from person to person, concerns about future mutations remain. The study suggests that more changes might be necessary for the virus to achieve efficient human-to-human transmission. A recent case in Canada, where a teenager was hospitalized with a mutated strain of H5N1, further illustrates the potential for change. Fortunately, no evidence of person-to-person spread was found in that case.
Health experts stress the importance of monitoring the virus closely. “We may not realize a pandemic has begun until it’s already underway,” Sutton warned. Paulson also called for preparedness, suggesting that stockpiling bird flu vaccines and planning for their distribution could be crucial if the virus evolves further. For now, officials maintain that the risk to the general public remains low, but vigilance is key.