The Lancet, 1 March 2025

Editorial

H5N1 avian influenza: technical solutions, political challenges

It has been almost 1 year since the detection of an unprecedented spread of highly pathogenic avian influenza A(H5N1) in dairy cows in the USA. Although there is still no evidence of human-to-human transmission and human deaths have been rare, concern over the potential impacts on human health remains high.

The B3.13 genotype has predominated in cattle and human beings, causing largely mild disease, but there have been worrying recent developments. In the past couple of months a new genotype, D1.1, resulted in the death of a person in Louisiana—the first death in the USA from H5N1—while a teenager in Canada was critically ill for several months. On Jan 31, the US Department of Agriculture announced the first detection of D1.1 in dairy cattle in Nevada, followed by another independent introduction in Arizona. The risk to the general public is still considered low, but the range and sustained infection of mammals, seemingly independent spillover between species, and potential for severe disease, demand urgent action. Animal welfare, public health, and commercial trade are at stake.