Vaccine expert Dr. Paul Offit is the author of the new book Deadly Choices: How the Anti-Vaccine Movement Threatens Us All. We talked with Dr. Offit about realities of vaccine-preventable diseases, the importance of herd immunity, just how contagious measles really are, why you shouldn’t have chickenpox parties, why neither he nor Jenny McCarthy are autism experts, why it is unethical to run studies featuring vaccinated versus unvaccinated children, and just how extensively the autism-vaccine hypothesis has been debunked. [update 2/1] Dr. Offit discussed many of these same topics during his 1/31 guest spot on The Colbert Report. What is your elevator pitch for parents concerned about vaccines and autism? I think raising the concern is reasonable. Children get vaccines, and for some children, the signs and symptoms of autism may appear soon after receiving the vaccine, so asking those questions is reasonable. The good news is that the question…