There are a number of candidate vaccines that are in development for HIV/AIDS.
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.
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.
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.'