Took me a while to actually get around to reading up on this, but nursetim's comment is an important one since some people may have the impression that the flu is some invincible superbug now. Although the most common flu strain this season appears almost universally resistant to Tamiflu, it shows no sign of resistance to a different anti-viral, Relenza. In addition, all these Tamiflu-resistant samples were susceptible to the older anti-virals, too.