The government, for the first time, is urging doctors not to prescribe two antiviral drugs commonly used to fight influenza after discovering that the predominant strain of the virus has built up high levels of resistance to them at alarming speed.
A whopping 91 percent of virus samples tested by the Centers for Disease Control and Prevention this flu season proved resistant to rimantadine and amantadine, a huge increase since last year, when only 11 percent were.
The discovery adds to worries about how to fight bird flu should it start spreading among people. Health officials had hoped to conserve use of two newer antiviral drugs, Tamiflu and Relenza, because they show activity against bird flu, unlike the older drugs.
Now, because of the resistance issue, the newer drugs are being recommended for ordinary flu, increasing the chances that resistance will develop more rapidly to them, too, as they become more commonly used.
Just one more thing to worry about. And another reason to push harder for new, better antiviral drugs.