Large study shows—yet again—that the MMR vaccine does not cause autism

A major study confirms what doctors and scientists have been saying for years: there's no link between the MMR vaccine, which is used to vaccinate against measles, mumps and rubella, and the development of autism.

In one of the largest studies conducted to date on the subject, researchers in Denmark looked at data on more than 650,000 kids born from 1999 to 2010. Rather than ask parents whether their kids were vaccinated—and if they also had autism—they looked at information collected in the Danish Civil Registration System and the Danish Vaccination registry, as well as other reports of autism diagnoses. They found that kids who weren't vaccinated were just as likely to have autism as those who weren't. About one percent—or 6,517 kids—were diagnosed with autism while they were part of the study.

The scientists also wanted to see if certain factors, like having older parents, pregnancy complications, smoking, low-birth weight or the child's age at vaccination, made a child more susceptible to developing autism as a result of the vaccine. They found that, with all of these factors, the risk of developing autism was the same whether the child had gotten the vaccine or not.

The study, published in the Annals of Internal Medicine on March 5, comes at a time when vaccine skepticism is reaching a critical point. The World Health Organization has named vaccine hesitancy as one of the biggest global health threats of 2019, and measles outbreaks in communities where it's already been eradicated are putting babies and other immunocompromised people at risk.

The research anti-vaxxers often cite is the 1998 Andrew Wakefield study, published in the medical journal The Lancet, which did link the MMR vaccine to autism, but has long since been debunked.

"Since the publication of the initial report by Wakefield and colleagues, and despite many subsequent studies not finding an association between MMR vaccine and autism, public concerns regarding a potential link between MMR vaccine and the development of autism have persisted," says Saad Omer, a professor of global health, epidemiology and paediatrics at Emory University, in Atlanta, GA, in an editorial that accompanied the study in the journal.

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