No link has been found between the measles, mumps, rubella (MMR) vaccine, and autism in largest, single study to date.
Researchers published their report on Monday in the journal .
The authors, all members of the Statens Serum Institut, an institution similar to the CDC in the United States, followed a cohort of 657,461 Danish children born between 1999 and 2010 for a decade to see if receiving the MMR vaccine had a significant impact on a child developing autism or symptoms of autism spectrum disorder.
It did not.
No increased risk of autism was observed when comparing children who had received the MMR vaccine and those that did not.
“It is time to bury the hypothesis that MMR causes autism,” Dr. Mads Melbye, study author, professor, and director of the Statens Serum Institut, Copenhagen, Denmark, told Healthline.
“The fact that we were able to study ALL Danish children forward in time, with high-quality information on who and when they were vaccinated with MMR, and then, from other independent registries, who of the children developed autism, gives high credibility to the result of this study.
In total, 6,517 children in the cohort were diagnosed with autism.
The study builds off another slightly smaller study conducted in Denmark, which Melbye also helped to author, published in 2002. That study followed a similar model using a cohort of 537,303 Danish children born between 1991 and 1998.
Their findings were the same then as they are now: There is no discernible increase in risk of autism from the MMR vaccine.
“Both the study we just did and the one we published in 2002 in New England Journal of Medicine, are based on very large cohorts and on register information of high validity. And both found no difference in risk of autism in those MMR-vaccinated compared to not vaccinated,” said Melbye.
The new study goes into even finer detail than the previous one, addressing numerous potential criticisms. Specifically, they note that in large cohort studies, it is possible that certain high-risk groups, such as the siblings of children with autism, may be overlooked.
Younger siblings of children with ASD are up to 14 times more likely to have it when compared with the general population.
Melbye and colleagues addressed environmental and familial risk factors for autism in their study, creating high-risk subgroups, such as siblings. Still, even in these subgroups, no appreciable difference was found for autism risk.
The study has been celebrated by doctors and public health officials as a reminder of the safety of vaccines at a time when it is sorely needed.
“Although many other well-designed studies have likewise shown that the measles vaccine does not increase a child’s risk for measles, this new study provides even stronger evidence about its safety and should be reassuring to even the most skeptical parents,” Dr. Andrew Adesman, chief, Developmental & Behavioral Pediatrics, Cohen Children’s Medical Center, New Hyde Park, NY, told Healthline.
Measles, a potentially fatal, but entirely preventable disease, has shown a disturbing resurgence in the United States, Canada, and Europe.
Nearly two decades ago, the Centers for Disease Control and Prevention proclaimed measles , but that no longer appears to be the case.
The World Health Organization lists “vaccine hesitancy,” defined as “the reluctance or refusal to vaccinate despite the availability of vaccines,” alongside the deadly Ebola virus as one of the 10 biggest threats to global health in 2019.
By far the most predominant driver of the anti-vaccination movement is the link between autism and vaccines — a link that has repeatedly been dismissed.
The association between autism and the MMR vaccine was first published in a fraudulent, widely-criticized, and subsequently retracted study in The Lancet in 1998.
Since that paper and the rise of the anti-vaccination movement, doctors have fought to reassure the public of the safety of immunization.
The publication of this research should be a major victory toward that end.
“To the extent that there has been a recent increase in measles cases due to parents not vaccinating their children, this study provides compelling evidence that the measles vaccine does not lead to autism in healthy children or in children believed to be at increased risk for autism,” said Adesman.