How easily can deadly bird flu spread from cows to people? We're still not sure

Embargoed until: Publicly released: 2025-04-17 01:00

International

What does this mean?

Jump to: MultimediaAttachmentsExpert Reaction

Previous research has suggested that deadly H5N1 bird flu in cows can spread to people relatively easily after showing that the virus can bind to a type of acids found in human airways, called sialic acids, and could then be spread to ferrets. That suggested the virus could soon start to spread between different mammals, including us, potentially leading to a new global pandemic. However, a pair of new studies has cast doubt on those findings. The first, by US and UK researchers, found H5N1 in cows binds poorly to human sialic acids, suggesting the virus cannot spread easily from cows to people. The second study, by US scientists, looked at whether the virus binds more easily to receptors in birds than mammals, even after infecting cows, and found that to be the case.  The team found no evidence of a shift towards infecting humans or other mammals as the virus has spread and evolved, although this should be the subject of continuous monitoring, they say. Finally, the authors of the original study which suggested the virus could spread between mammals respond to the new work. Differences in the methods used may explain the contrasting findings, they say, and we should not be complacent about the potential for H5N1 to become the next global pandemic.