Study rules out link between autism, MMR vaccine even in at-risk kids

From the "You've Heard This Before (And May Still Not Believe It) Department": Another study has found early-childhood vaccines do not cause autism. This time, researchers examined the one slight possibility that had been left out of the previous dozen or so studies - that immunizations might cause the disorder in a small group of children who were already primed to develop it.

The study of nearly 100,000 children found that toddlers known to have an elevated risk of autism were no more likely to be diagnosed with the disorder if they were vaccinated against measles, mumps, and rubella than if they weren't. What's more, the diagnosis rate for high-risk children who received the MMR vaccine was the same as for immunized children with no family history of the disorder, according to the report last week in the Journal of the American Medical Association.

By hunting for - and failing to find - a link between the MMR vaccine and autism spectrum disorders, or ASD, in children with an older sibling who had the disease, the study leaves no doubt that the two are not connected, experts said.

Though "abundant" evidence demonstrates that the MMR vaccine does not lead to ASD in the general population, it was still worth investigating whether there might be a connection in this group, said Bryan H. King, an autism specialist at Seattle Children's Hospital, author of an editorial that accompanied the findings.

By showing such fears to be unfounded, the study - and others before it - makes plain that "the age of onset of ASD does not differ between vaccinated and unvaccinated children, the severity or course of ASD does not differ between vaccinated and unvaccinated children, and now the risk of ASD recurrence in families does not differ between vaccinated and unvaccinated children," King said.

But the vocal minority of parents who contend there is a cause-and-effect relationship aren't likely to be swayed. "Eight million studies are not going to convince people," said James Cherry, a pediatric infectious-diseases specialist at UCLA.

- Los Angeles Times