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MARK SAWYER, MD: Certainly we've seen an increase in autism and that's really driving the need to understand what causes autism and, at the same time, we're giving more vaccines. So naturally, people ask the question, 'Are those two things related to each other?'

PAUL A. OFFIT, MD: Whenever we've looked at vaccines as a cause of autism, we haven't found it. And that's consistent with the fact that when you look at all the research for autism, it really drives you to events that occur in the first or second trimester. It really appears that if you're autistic at age five, you're autistic at age two, and frankly, you're born with autism, which, again, would exonerate vaccines.

MARY BETH KOSLAP-PETRACO, DNP(c), CPNP: What I think is happening with autism is we are doing a far better job of diagnosing autism than we ever did before. We've changed the children who qualify for that diagnosis.

ALISON SINGER: It's natural when your child is diagnosed with a developmental disability to want to blame someone or something, because we know that our children are going to face such tremendous challenges in their lives. Believe me, I understand that.

But I always tell parents not to let their hurt and their anger get in the way of the data. I always encourage them to look at the science and to focus on the facts. And the facts are clear in this case.