The director of the U.S. Centers for Disease Control and Prevention (CDC) says that the prescription drug Tamiflu isn't working against the virus strain that is causing this year's influenza in the United States. But experts say it is too early to tell if the Tamiflu-resistant strain will continue to dominate this year's influenza cycle, and there is another drug--Relenza--that can be tried. However, the CDC is also reporting that this year's vaccine does appear to be fighting the flu.