 Well, there's one challenge that has been there forever, and that will always be there, and that is the emergence and reemergence of new diseases. One of the things, again, that I mentioned at the Ideas Festival is that microbes for a variety naturally evolve and reemerge. When you, being society, the human species, perturb the environment in general or their environment, and you could do it a lot of different ways. You can encroach upon rain forest, you can encroach upon places where animals, you get exposed to 70% of the new infections, jump species from an animal to a human, HIV, AIDS is the classic example of that. So you constantly have this threat of new microbes emerging. Most of the time, there are little blips on the radar screen that are curiosities. Every once in a while, maybe twice a century or less, you get the emergence of a disease that transforms the world in the sense of catastrophic effect on global health. In the 20th century, it was the 1918 flu pandemic that killed 50 million people in one winter, and then HIV, AIDS that was first recognized in 1981. So you never know when this next threat to the human species. So that's one thing that we have to be concerned about that keeps me up at night about what is the next challenge going to be. And the other thing is, when you're talking about global health, is the disparity of availability for countermeasures for health and the relationship between poverty and infectious diseases and vice versa. They feed each other in the poorest country. You don't have clean water. You have all the illnesses that are associated with lack of accessibility of clean water. You have vaccine preventable diseases for which vaccines don't get to the children, you know, thousands and thousands and thousands of babies a year die of measles, a completely preventable disease, if vaccinations are made available for them. Diorural diseases, respiratory diseases, one million babies a year die of malaria. I mean, and malaria can be handled with the proper approach with bed nets and therapy, etc, etc. So we have a long way to go. So the things that bother me are the unexpected, the new HIV, the new pandemic flu, but also the fact of the enormous disparity in the world between the rich nations and the poor nations and the unnecessary deaths and lack of productivity and economic deprivation that continues to feed the poverty and the infectious diseases that come from it. Those are the things that I get concerned about the most. You know, yes, but you don't want to, it's not a showstopper for society. Pandemics occur in the 20th century. There were three, one very severe, two much, much less severe. 1918, 1957, 1958, 1968. We have now percolating in Southeast Asia and in some African countries, eight, what they call a bird flu, a flu that's very virulent. When it gets into chicken flocks, it devastates them. Tens and tens of millions of chickens have either died or had to be culled because of this. Rarely, rarely, it jumps species from chicken to human. There have been about 350 cases since 2003, about 240 or somewhat deaths, so it's about a 60 somewhat percent mortality. Very unusual to jump species and extremely unusual to go from one human to another, usually within the same family. So it hasn't evolved molecularly the capability of efficiently going from human to human. It might not ever do that, and it is, in fact, probably unlikely that it will ever. But the wake-up call that it gives us is that we have got to be able, and we're getting much, much better at it right now, to develop vaccines that have the capability of protecting against these different types of strains of influenza. We have pretty good vaccines each year that we modify them a little bit each year to keep up with the drifting kind of differences of flu from one year to another. What we need are the kinds of vaccines that can handle any type of flu. That's one thing. That's the scientific approach. The logistic issue is how do you get enough of it made to be distributed in case we do have a pandemic? So the short answer to your question about the pandemic flu, it's still percolating in Southeast Asia. It has not gotten any better at going from human to human. In that respect, that's very, very good news, but it was a wake-up call for us to know that a pandemic can emerge. So what we need to do is we need to join our efforts of getting a better vaccines and drugs for seasonal flu at the same time as we extrapolate that to our ability to respond to a pandemic flu.