Tamiflu no longer works for dominant flu strain

U.S. health officials say almost 100% of the type A H1N1 strain showed resistance to the leading antiviral drug. So far, the influenza season has been mild.
By Mary Engel
LA Times

February 4, 2009

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.

In response, the Centers for Disease Control and Prevention issued new guidelines to physicians in December. Doctors were told to substitute an alternative antiviral, Relenza, for Tamiflu, or to combine Tamiflu with an older antiviral, rimantadine, if the H1N1 virus was the main strain circulating in their communities.

(More here.)