Sunday, October 16, 2005

More instances of Tamiflu resistance?

Helen Branswell of Canadian Press says that Dr. Frederick Hayden, a professor of clinical virology at the University of Virginia, has told her in an interview that there is additional evidence of Tamiflu resistant H5N1 yet to be published. (hat tip, crofsblog) Hayden should know, as he is co-chair of an international group that monitors reports of drug resistance to neuriminidase inhibitors, the class of drugs to which Tamiflu belongs. Without giving details, Hayden said he is comfortable with the statement in the recent WHO consensus report published in the New England Journal that there were "several cases," although the only identified case was the one just published in Nature (see post here).

The just published report doesn't settle the question as to whether Tamiflu resistant clones are less dangerous than sensitive ones, as many virologists believe. This seemed to be true in the just reported Vietnamese case and in resistant clones of the currently circulating H3N2 virus (ref: Lancet. 2004 Aug 28-Sep 3;364(9436):759-65).

It would be nice if that turned out to be true in general, but it would be foolish to count on it. So this is another factor to take into account when preparing a national or local plan. Stockpiling Tamiflu is only one possible response, not the whole plan. Not even close.