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MARK SAWYER, MD: People talk about the H1N1 being rushed or being hurried or in some way being experimental. Actually, H1N1 vaccine for influenza is being made in the exact same way that every other influenza vaccine is made.

PAUL A. OFFIT, MD: Influenza is a tough virus to pin down. I mean, every year it changes so much so that immunization or natural infection the previous year really doesn't protect against disease the following year.

So every year, essentially, we make a new influenza vaccine. We call it the seasonal flu vaccine—and that seasonal flu vaccine typically contains new strains every year. No different this year.

MARK SAWYER, MD: If H1N1, the infection, had been identified just three months earlier, it would've just been put in the regular vaccine like we change them every year and you never would've known.

PAUL A. OFFIT, MD: It wasn't rushed to market anymore than we rush any flu vaccine to market. Remembering that we do need to generate new flu vaccines every year, it just happens to be that this year that virus, the novel H1N1, is spreading across the country like wildfire and is causing a fair amount of hospitalization and death.