New sibling study finds no vaccine-autism link

New research on autistic siblings, published this week in The Journal of the American Medical Association (JAMA), failed to find any association between autism and the measles, mumps, and rubella vaccine. The finding is consistent with other studies doctors say have disproven any vaccine-autism link.

The measles, mumps, and rubella (MMR) vaccine, sold in the United States by Merck under the brand name M-M-R II, is routinely given to children after their first birthday, with a follow-up shot between the ages of 4 and 6.

Some parents, citing an upsurge in autism spectrum disorder in the past few decades, have worried the MMR vaccine is responsible. That fear has contributed, at least in part, to vaccine refusals epidemiologists blame for outbreaks of preventable diseases, such as the recent Disneyland measles outbreak that sickened dozens this year.

Autism spectrum disorder, sometimes called ASD, includes a range of mild to severe mental disabilities involving difficulties in communication and motor coordination.

In the new JAMA study, researchers affiliated with UnitedHealth Group, an insurance company, mined an insurance claims database to measure the prevalence of autism spectrum disorder and vaccination rates among 95,727 U.S. children born between 2001 and 2007.

“Consistent with studies in other populations,we observed no association between MMR vaccination and increased ASD risk among privately insured children,” the researchers concluded.

The study only included children with an older brother or sister. Children with an autistic sibling are known to have a higher risk of developing autism themselves. In the study, 7 percent of children with an autistic older sibling were diagnosed with autism, compared with 1 percent of children without an autistic sibling.

But even among the higher risk group of children, researchers did not find any evidence the MMR vaccine triggered autism. That was true whether the child had received one or both doses of the vaccine.

Children in the study were slightly less likely to have received the MMR vaccine if they already had an older sibling with autism, presumably due to parents withholding the shot out of fear it played a role in the older child’s condition.

The JAMA study was funded by the U.S. Department of Health and Human Services.

A study published last year showed upticks in autism rates correlating with the introduction of vaccines made with human fetal cell lines, including M-M-R II. But multiple studies by researchers in various countries have found no increased risk of autism among vaccinated children.