Correct. Tamiflu is the best "General" antiviral drug available BUT, it will not be the "Silver Bullet" for whatever the Avian Flu mutates into. We won't know exactly what we are fighting until it shows itself..., then it will take months (at best) to develop and manufacture a SPECIFIC antiviral drug.
In any event, it can happen but when is a total unknown! At least it seems that Asis is fully on board now in recognizing the danger and will not hide an outbreak to "Save Face"...
It's never happened and I doubt it ever will.
A giant meteor could hit the earth and wipe us all out,it can happen but when is a total unknown!