Yes, the seasonal flu is changing every year. That is changing. That is why you have to have a new vaccine every year. So this meeting that takes place for the northern hemisphere takes place in Geneva. The southern hemisphere does the same. It takes place in September. They decide what the new strains are. This is the reason, because these strains are drifting, they call it. They drift.
With a pandemic strain, it's slightly different. It's a completely new strain. Everybody is naive. There's no immunity there at all for these new stains. That's why they move around so fast. And this has been helped, of course, by air travel.