Prior exposures to specific types of seasonal influenza viruses promote cross-reactive immunity against the H5N1 avian influenza virus, according to new research from the Perelman School of Medicine at the University of Pennsylvania.

No new human cases of avian influenza have been reported, and poultry infections are low so far in March. But infections in cats are continuing, and new research is raising concerns about the virus

Avian flu is hitting California’s San Joaquin Valley hard — nearly 20 million chickens, ducks and turkeys have been killed in the region since 2022, according to data from the Centers for Disease Control and Prevention.