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MARK SAWYER, MD: Autism is a difficult disease to deal with and I sympathize with parents who have children with autism. But I think it's a big mistake for them to then conclude that they shouldn't immunize their other children.

For one thing, there's no evidence at all that vaccines are related to autism. And if their other children are left unprotected, then they're just going to bring disease home and the child with autism is going to have additional problems related to those infections.

MARY BETH KOSLAP-PETRACO, DNP(c), CPNP: Why would I want to expose a child who has a developmental disorder to a vaccine-preventable disease and possibly give them more problems because of the after effects from the vaccine-preventable disease? We know that there is no connection between the vaccines and autism, so we need to vaccinate the autistic child as well as the siblings.

ALISON SINGER: We know from twin studies and genetic studies that the younger siblings of children with autism are at a much higher risk for being diagnosed with autism than the general population. In general, there's a one in 100 chance that a child will be diagnosed with autism. But for siblings of children with autism, it's around one in 15. So we know that those children are at much higher risk.

But they're not at higher risk because of vaccines. In fact, one thing I'm very much concerned about is because so many parents have been frightened about vaccines; they're not vaccinating their younger children. And in fact, the younger siblings of children with autism are probably one of the most at-risk populations for infectious disease because they're not being vaccinated.

PAUL A. OFFIT, MD: So, if a mother has a child with autism, she can be reassured then that vaccines were not the cause and she can safely immunize her younger child because if she doesn't, then all she's done is expose that child to the risk of potentially fatal infectious diseases without, in any sense, lessening the risk of autism.