Researchers say they found no increase in autism diagnoses among children who received the measles-mumps-rubella vaccine, even in those with a sibling on the spectrum.

The measles-mumps-rubella (MMR) vaccine does not increase the risk of autism even for children in high-risk families.

That’s the conclusion of a large-scale study published today in the Journal of the American Medical Association.

Researchers studied the records of 95,727 children with older siblings who were enrolled in health plans from 2001 to 2012. Of those, 1,929 children had an older sibling who’d been diagnosed with autism spectrum disorder (ASD).

In all, 994 children in the study were diagnosed at some point with ASD. Of those, 134 had a sibling with the disorder. The other 860 did not.

The MMR vaccination rate for children without siblings with autism was 92 percent by the age of 5. The rate was 86 percent for children who had an autistic sibling. This may reflect the mistaken belief held by some parents that the MMR vaccine increases autism risk in vulnerable kids. 

Get the Facts: Vaccine Recommendations for Children »

Researchers said there was no difference in ASD diagnoses among the children with autistic siblings in the vaccinated and unvaccinated groups. The same was true for children with no autism cases in their immediate family.

“I hope the study is reassuring to parents,” said Dr. Anjali Jain of the Lewin Group consulting firm and a co-author of the study. 

Jain told Healthline this latest study backs up previous research that concluded there is no link between autism and the MMR vaccine.

This study, she added, was also based in the United States and focused on children who have siblings with ASD.

Read More: Measles Cases Spread in California Due to Unvaccinated Children »

She said researchers were looking to see if there were any triggers in the childhood vaccine that might spark autism in high-risk families. They found none. 

She said it appears genetics and environment are bigger risk factors in families with more than one child with autism.

“I do consider the vaccine to be a safe vaccine,” said Jain, who is a pediatrician.

Healthline contacted the group Moms Against Mercury for comment, but they did not respond. Officials at anti-vaccination groups have said there is a connection between the MMR vaccine and some ASD diagnoses. 

Related News: What Is the Current State of Vaccines in Developing Countries? »