Research Continues to Disprove Link Between Autism and Vaccines

Dr. Bryan King worries that each time the media includes the MMR vaccine and autism in the same sentence, even if reporting the lack of association, the false idea of a linkage between the two is perpetuated.

A significant body of validated research over the last 15 years has found no link between the measles-mumps-rubella (MMR) vaccine and autism spectrum disorders, yet the false myth that this vaccine may cause or intensify the disorder continues to circulate among some families of children with autism. As a result, some parents delay or forgo the life-saving MMR vaccine for their children.

A new study, led by The Lewin Group and titled “Autism Occurrence by MMR Vaccine Status Among U.S. Children With Older Siblings With and Without Autism,” has been published this week in the Journal of the American Medical Association (JAMA). This study further refuted the concern that children who are at higher risk of developing autism could be negatively impacted by the MMR vaccine. The study included approximately 95,000 children with older siblings and found that receipt of the MMR vaccine was not associated with an increased risk of autism, regardless of whether older siblings had autism.

Dr. Bryan King, director of Seattle Children’s Autism Center and Department of Psychiatry and Behavioral Medicine at Seattle Children’s Hospital and an investigator in Seattle Children’s Research Institute’s Center for Child Health, Behavior and Development, has written an editorial published in the same JAMA issue addressing this research and the controversies that surround it. On the Pulse sat down with King to learn more about these important issues.

How did you feel when you learned that yet another research study found no link between the MMR vaccine and autism?

King: I was not surprised by the findings. For years we have had overwhelming evidence demonstrating no connection between the MMR vaccine and autism. At least a dozen well-designed studies have disproven the theory that the vaccine causes the disorder.

While I am glad we have yet another study to point to that debunks the myth that autism and MMR vaccine may be linked, I do have mixed feelings about the publicizing of this study, and others like it at this point. I fear that each time the media includes the MMR vaccine and autism in the same sentence, even if reporting the lack of association, the false idea of a linkage between the two is perpetuated. Parents just need to understand that the MMR vaccine is safe and move on from the idea that there may be serious risks associated with it.

With such a strong history of evidence showing the MMR vaccine does not cause autism, are there still parents choosing not to vaccinate their children out of fear of autism?

King: Surveys of parents who have children with autism suggest that many still believe the MMR vaccine could be a contributing cause. Parents of children with autism who were suddenly affected by a catastrophic developmental event between 1 and 2 years of age – around the time of their MMR vaccine – also ask whether the two events might be linked. Unfortunately, research proving such a link to be non-existent has not calmed all of parents’ fears.

Not surprisingly, this study by The Lewin Group demonstrated that parents of children with autism may have chosen to delay immunization in subsequent children until they were certain any risk had passed. Unfortunately, such waiting potentially exposes children to deadly, contagious diseases early in life.

If existing research has not convinced all parents that the MMR vaccine does not cause autism, what more can be done?

King: While we have research demonstrating some factors that do not cause autism, we still don’t know definitively what actually contributes to the onset of this disorder. It’s a lot easier to embrace something identified as a cause than evidence that something is not a cause. It’s frustrating for everyone that we don’t have these answers yet and that creates the opportunity for unproven theories to take hold.

The good news is researchers are actively searching for factors that contribute to autism risk and we are seeing progress in this field.

What are some examples of potential factors being studied?

King: Another study by Kaiser Permanente, published in the same issue of JAMA, investigates whether maternal diabetes increases autism risk. Researchers report that more than 99% of infants who were exposed to maternal diabetes in utero did not develop autism, however, there was an increased risk in children exposed to gestational diabetes before 26 weeks.

This research is particularly interesting because it directs attention for autism risk to the prenatal environment, long before children are exposed to the MMR vaccine for example. It’s quite likely that the developmental pathways for autism are created much earlier than clinical symptoms manifest in children.

It seems that autism research and treatment is often shrouded in controversy, what can be done about that?

King: Controversy seems to follow autism like the tail of a kite. But, to be fair, controversy can be a stimulus for progress. These studies move the field forward toward a more focused and productive search for factors contributing to autism risk. They also provide information to support families affected by autism.
The field is long overdue for calm weather, but the forecast is increasingly promising. The more we learn about accurate causes of autism, the easier it will be to debunk myths.


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