Ellen Phiddian
Cosmos science journalist
The H5N1 bird flu strain circulating in the USA is good at mutating to infect new hosts, according to a genetic study – but it’s still vulnerable to antivirals.
The current H5N1 flu strain, which started spreading on US dairy farms in March 2024, has been transmitted to a handful of people working with infected animals. It has not yet transferred from person to person, and while one person has died in the US, most patients have experienced mild infection.
In the study, published in Emerging Microbes & Infections, researchers examined strains of the virus taken from a human patient and dairy cattle early in the 2024 outbreak.
They looked for genetic differences between the human and cattle samples, and tested the severity of each strain in mice.
“There are 9 mutations in the human strain that were not present in the bovine strain, which suggests they occurred after human infection,” says co-author Dr Luis Martinez-Sobrido, a researcher at the Texas Biomedical Research Institute, USA.
The human strain also replicated more quickly in mice.
“Fortunately, the mutations did not affect the susceptibility to FDA-approved antivirals,” says first author Dr Ahmed Mostafa Elsayed, also at the Texas Biomedical Research Institute.
The researchers say that the quick mutations of the virus highlight the risk to people.
“The clock is ticking for the virus to evolve to more easily infect and potentially transmit from human to human, which would be a concern,” says Martinez-Sobrido.
