No Link Between MMR Vaccine and Autism, Even in High-Risk Kids

NIH: Study after study has found no link between autism spectrum disorders (ASD) and the measles-mumps-rubella (MMR) vaccine—or any vaccine for that matter. Yet many parents still refuse or delay vaccinations for their young children based on misplaced fear of ASD, which can be traced back to a small 1998 study that’s since been debunked and retracted [1]. Such decisions can have a major negative impact on public health. With vaccination rates in decline, we’ve recently seen the resurgence of measles and other potentially fatal childhood infectious diseases. Among the parents most likely to avoid getting their kids vaccinated are those who already have a child with ASD. So, it’s especially important and timely news that researchers have once again found no link between MMR vaccines and ASD—even among children known to be at greater risk for autism because an older sibling has the developmental brain disorder. A new study published in JAMA analyzed 2001-2012 health insurance claims for more than 95,000 children, ages birth to 5, plus their older siblings. More than 1,900 of the children studied had an older sibling with ASD, which is known to place them at greater risk of being diagnosed with ASD themselves.

Overall, about 1 percent of the children were diagnosed with ASD during the time period studied. The rate was significantly higher—nearly 7 percent—among the children with an older sibling with ASD, but the risk did not increase if they had received the MMR vaccine. In fact, in families that had an older child with ASD, a vaccinated younger sibling was actually somewhat less likely to receive an autism diagnosis.
Current U.S. recommendations call for two doses of MMR vaccine in children at age 12 to 15 months and then again at age 4 to 6. Given the distressing resurgence of measles in California and elsewhere, and this new study showing once again the lack of any connection of MMR vaccine and ASD, it’s more critical than ever that parents protect their children against measles and other infectious diseases by staying current with vaccinations.
The consequences of not vaccinating children are serious: last year in the United States, 668 people contracted measles in 27 states [3]. That’s no small matter because measles can lead to ear infections, pneumonia, seizures, brain damage, and even death. Furthermore, parents have a responsibility not only to their own children, but to the community—it’s only by achieving a very high level of population immunity that outbreaks can be prevented. That’s particularly crucial for those children with cancer and other diseases that cause immunosuppression. They cannot be vaccinated and depend on the so-called “herd immunity” of the community for protection against a potentially fatal infection.
As for ASD, the condition remains a major challenge for scientists and families alike. The latest research is just one part of a much larger effort by NIH and its partners to understand the genetic and environmental risk factors for ASD, as well as to develop more effective pharmacological and behavioral interventions for affected children.
References:
[1] MMR vaccine & autism. American Academy of Pediatrics, April 29, 2014.
[2] Autism occurrence by MMR vaccine status among US children with older siblings with and without autism. Jain A, Marshall J, Buikema A, Bancroft T, Kelly JP, Newschaffer CJ. JAMA, 2015 April 21; 313(15):1534-1540.
[3] Measles cases and outbreaks. Centers for Disease Control and Prevention (CDC), April 20, 2015.