You can have an epidemic in a state. You can have it in a region. You can have it in a country where the critical level of disease passes a certain threshold, and we call that an 'epidemic threshold.'
I think it would be over-exaggeration to think that there are millions of viruses ready to jump on us and bring us back to the 14th century. That would be looking over a ledge that isn't there.
Testing two vaccines against different H1N1s at the same time has never been done.
There are a number of candidate vaccines that are in development for HIV/AIDS.
The Europeans have lots of data on the use of adjuvanted flu vaccine in the elderly, but I don't think anybody has really good data on adjuvants in children.
The nature of a protective immune response to HIV is still unclear. Because in a very, very unique manner, unlike virtually any other microbe with which we're familiar, the HIV virus has evolved in a way that the immune system finds it very difficult, if not impossible, to deal with the virus.
