Researchers from the Centers for Disease Control and Prevention have identified what they believe to be the first case involving transmission of a Tamiflu-resistant pandemic H1N1 virus from one person to another but have so far found no evidence that the virus spread beyond the initial two known patients. But the findings highlight the dangers of using antiviral drugs like Tamiflu in an effort to prevent infections by the virus, commonly known as swine flu. Researchers fear that indiscriminate use of the drugs will lead to widespread resistance, as is now the case with seasonal flu, and the new findings provide the first hint that this could easily happen.
As of Sept. 4, the CDC has identified a total of nine cases of resistance to Tamiflu, known generically as oseltamivir. The drug's manufacturer, Roche Holding, said Monday that it knows of 13 cases worldwide.
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Source: http://latimesblogs.latimes.com/booster_shots/2009/09/first-transmission-of-antiviralresistant-swine-flu.html 
