Measles vaccine not linked to autism, even in high-risk kids: study

The measles-mumps-rubella (MMR) vaccine does not increase the risk of autism, even among children considered at a high risk for the disorder, according to a study of about 95,000 children with older siblings.

The MMR vaccine controversy began in 1998, after the British medical journal The Lancet published a fraudulent research paper connecting the vaccine with autism. The paper was later retracted, and studies over the past 15 years have consistently showed no evidence to support the alleged association.

Despite this, surveys of parents who have children with autism suggested that many believe the MMR vaccine was a contributing cause. This belief, combined with knowing that younger siblings of children with autism are already at higher genetic risk for the disorder compared with the general population, prompted these parents to avoid vaccinating their younger children.

Researchers at the Lewin Group, a U.S. healthcare consulting firm, examined the incidence of autism in 95,727 U.S. children, who all have older siblings. Among these children, 1,929, or 2 percent, have an older sibling with autism.

Overall, 994 children in the study were diagnosed with autism during follow-up. Of those, 134 had a sibling with the condition. The other 860 did not.

The MMR vaccination rate for children with non-autistic siblings was 84 percent at two years old and 92 percent at five years old. In contrast, the rate for children with autistic siblings was 73 percent at two years old and 86 percent at five years old.

The researchers reported Tuesday in the U.S. journal JAMA that they found no difference in the incidence of autism between the vaccinated and unvaccinated children, regardless of whether their older siblings had the disorder.

In an accompanying editorial, Bryan King of the University of Washington and Seattle Children's Hospital said: "The only conclusion that can be drawn from the study is that there is no signal to suggest a relationship between MMR and the development of autism in children with or without a sibling who has autism."

"Taken together, some dozen studies have now shown that the age of onset of ASD (autism spectrum disorders) 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 wrote. Endite