Bird flu isn’t what circulating generally right now. That’s just the regular seasonal flu. Avian flu is a whole other can of worms in that it’s running rampant among birds, it hasn’t (yet) shown the ability to readily spread in air between mammalian hosts. The longer it hangs around, though, the more chances it gets to evolve that capability – and in fact if the leaked CDC papers that made news recently are to be believed, some strain of on it might have done so.