Laboratory-confirmed influenza B infection in immunized long-term care facility residents receiving oseltamivir prophylaxis in Ontario.

We report on an influenza B outbreak in an Ontario long-term care facility in which 2 immunized residents receiving oseltamivir prophylaxis for at least 5 days developed laboratory-confirmed influenza B infection. All isolates were tested for the most common oseltamivir resistance, and none of them had resistance identified.