The lollipop "heads" of hemagglutinin proteins evolve more frequently while the "sticks" of the hemagglutinin lollipops, called stalks, don't evolve as quickly. Researchers tested blood samples from ...

Very few humans have gone up against bird flu. But we've all dealt with seasonal flu for years. Some of our immune systems might be primed to fend off a worse case, research finds.

Very few humans have gone up against bird flu. But we've all dealt with seasonal flu for years. Some of our immune systems might be primed to fend off a worse case, research finds.

Hemagglutinin, or the HA protein ... The heads can be very different, but those sticks, technically called "stalks," can sometimes be quite similar. That happens to be the case for bird flu ...