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Bird flu in cows shows no signs of adapting to humans — yet

H5N1 grows well in dairy cow udders, which may actually be good news for people

15 milliliter plastic vials with light blue screw tops partially filled with milk stand in a cardboard containers. On the side in black marker is written Flu Milk Collection. These samples are waiting to be tested for H5N1 bird flu in dairy cattle.

Vials of milk await testing for avian influenza at Cornell University in Ithaca, N.Y. in December 2024. Infecting dairy cattle hasn’t yet given H5N1 bird flu an evolutionary boost toward easy person-to-person spread.

Michael M. Santiago/Getty Images

By Tina Hesman Saey

WASHINGTON — When traces of H5N1 bird