To date, tests of isolates from eight farms in Canada have yielded a rare neuraminidase (NA) protein mutation known as H275Y that has shown resistance to oseltamivir, according to a new research ...

All tested viruses were susceptible to oseltamivir and other neuraminidase inhibitors, including zanamivir and peramivir, as well as baloxavir, a newer drug that targets a different viral protein.

"As of February 19, 2009, resistance to oseltamivir had been identified among 264 of 268 (98.5 percent) U.S. influenza A (H1N1) viruses tested," the researchers wrote in the Journal of the ...