A milder than usual U.S. flu season is masking a growing concern about widespread resistance to the antiviral drug Tamiflu and what that means for the nation's preparedness in case of a dangerous pandemic flu. Tamiflu, the most commonly used influenza antiviral and the mainstay of the federal government's emergency drug stockpile, no longer works for the dominant flu strain circulating in much of the country, government officials said Tuesday. Of samples tested since October, almost 100% of the strain -- known as type A H1N1 -- showed resistance to Tamiflu.
