New large study finds no link between measles vaccine, autism

At a time when measles outbreaks are mounting among clusters of unvaccinated children, notably in Washington state, New York and Texas, a new large study published this week found no association between the measles vaccine and autism — a reason often given by parents for rejecting inoculation.

The new research confirms what has long been widely accepted in the scientific community, and it echoes findings of a 2002 study by members of the same team of scientists about the vaccine, known as MMR because it protects against measles, mumps and rubella.

But the findings come at a moment of resurging suspicion about vaccine safety, that has been promulgated at the far edges of the internet and on mainstream sites such as Amazon, Facebook and Pinterest. Many of those companies have taken steps in recent weeks to remove anti-vaccine content, but Monday, the president of the American Academy of Pediatrics, Dr. Kyle E. Yasuda, wrote to the chief executives of Google, Facebook and Pinterest, urging further action in "an urgent request to work together to combat the dangerous spread of vaccine misinformation online."

In emphatic language, the researchers, who followed 657,461 Danish children born between 1999 and 2010, stated in the Annals of Internal Medicine: "The study strongly supports that MMR vaccination does not increase the risk for autism, does not trigger autism in susceptible children, and is not associated with clustering of autism cases after vaccination."

Denmark offers a national vaccination program that is free and voluntary. At regular intervals, a team led by Dr. Anders Hviid, who is with the department of epidemiology research at Statens Serum Institut in Copenhagen, followed the children, 31,619 of whom remained unvaccinated.

The researchers further broke out subgroups of children according to other inoculations, and whether they had siblings with autism.

In time, 6,517 children received a diagnosis of autism. These researchers found no greater proportional incidence of the diagnosis between the vaccinated and unvaccinated children. This conclusion echoes a finding in their 2002 study of 537,303 Danish children, published in the New England Journal of Medicine.

Noting that measles outbreaks are becoming more commonplace in the United States as well as Europe, Hviid said: "U.S. researchers concluded that even a 5 percent reduction in vaccination coverage would triple measles cases, with significant health economic costs. A main reason that parents avoid or are concerned about childhood vaccinations has been the perceived link to autism."

The results of his study, he said, offered both reassurance and reliable data that no such link exists.

In an editorial accompanying the study, Dr. Saad B. Omer, a public health researcher at Emory University, and Dr. Inci Yildirim at the Emory School of Medicine, pointed out that it has been nearly a decade since the small study that set off alarms about a possible link between the vaccine and autism has been refuted and retracted. Yet resources are being continually poured into studies such as this latest one, to underscore the inaccuracy of that original misfire.

"In an ideal world," they wrote, "vaccine safety research would be conducted only to evaluate scientifically grounded hypotheses, not in response to the conspiracy du jour."

They said that doctors and public health officials needed to firmly label the association "a myth."

"Debunking a myth is tricky," said Dr. Sean T. O'Leary, a spokesman for the American Academy of Pediatrics and an associate professor of pediatrics at the University of Colorado at Denver. When you repeat the myth, he said, "you risk reinforcing it. All that parents remember about your complicated explanation about why vaccines don't cause autism is that they're somehow linked. So pediatricians should focus on the diseases we're trying to prevent, and if you have to address a myth, be clear that's exactly what it is. "

O'Leary, who researches immunization delivery challenges, said that particularly because clinicians are pressed for time, they need to be able to have solid information for parents who want to look further into the issue.

"It can be hard for parents to sort out what's real and what's not," he said.