Historically, a live vaccine induces more potent, lasting and broader immune responses than a killed vaccine. The body is seeing the microbe in a way that is much more analogous to a real infection.

The body's immune system is like any other system of the body. Each of them have their vital function for the human host.

The immune system's goal is to protect the body against invaders either from without, such as microbes, or from within, such as cancers and different types of neoplastic transformation.

You have to prepare for the worst, but it's entirely conceivable that we could have a moderate one. You have to prepare for a horrendous problem, but the general public shouldn't assume that we're going to see the worst case.

The good news is that we have a vaccine that can induce an immune response. But the sobering news is . . . we have a long way to go.

I think there was always rather intense interest at the level of the [HHS] department. Influenza has always been at the very top of my short list of things to be concerned about.