In the largest-ever study of its kind, researchers again found that the measles-mumps-rubella (MMR) vaccine did not increase risk for autism spectrum disorder (ASD). This proved true even among children already considered at high risk for the disorder.
In all, the researchers analyzed the health records of 95,727 children, including more than 15,000 children unvaccinated at age 2 and more than 8,000 still unvaccinated at age 5. Nearly 2,000 of these children were considered at risk for autism because they were born into families that already had a child with the disorder.
The report appears today in JAMA, the Journal of the American Medical Association.
“Consistent with studies in other populations, we observed no association between MMR vaccination and increased ASD risk,” the authors write. “We also found no evidence that receipt of either one or two doses of MMR vaccination was associated with an increased risk of ASD among children who had older siblings with ASD.”
The analysis looked at autism rates and MMR vaccination at ages 2, 3, 4 and 5 years. It showed no increased risk of autism with immunization at any age. In fact, autism rates were lower in the vaccinated groups. However, this might be because parents who see early signs of autism were more likely to delay or avoid vaccination, the authors speculate.
