Explainer: Vaccines are not linked to autism

Ignore a long-debunked study and internet scare-mongers. Science still confirms no causal tie


A now-discredited study once linked vaccines and autism. But many studies have since shown that vaccinations don’t lead to the brain disorder.

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Study after study confirms that vaccines are safe and save lives. So, most parents say yes to vaccines. They want to protect their children from diseases that can cause permanent harm or even death. Yet some parents say no. Many of these people base that refusal on a 1998 study that claimed to find a link between autism and vaccines.

Autism is a disorder that affects how the brain develops. Its symptoms can range from mild to severe. These symptoms can start to appear around the same time that kids get many of their vaccinations. So the 1998 study worried parents. Many feared their kids might develop autism after getting the MMR vaccine. That vaccine gets its name from the fact that it protects against three major childhood diseases: measles, mumps and rubella.

In fact, the 1998 study’s claims were false. Scientists debunked the report long ago. Still, some people haven’t learned about that or refuse to believe data that find no signs of an autism link. None. The most recent of these follow-up studies — and the largest — came out March 5, 2019 in the Annals of Internal Medicine. Like the others, it found no link between autism and vaccines.

In this new study, Anders Hviid of the Statens Serum Institut in Copenhagen, Denmark and his colleagues collected data on more than 657,000 Danish children between 1999 and 2013. They followed the children from age 1. Denmark provides free vaccines for children. As a result, most families chose to have their kids receive the MMR vaccine. But not all.

Over the study period, 6,517 children were diagnosed with autism. But the team found that children who got the MMR vaccine were no more likely to be diagnosed with autism than were those who didn’t get it. Groups that might be more susceptible to autism also did not have an increased risk from being vaccinated.

About that 1998 study

The initial claim of a possible autism link appeared in The Lancet. A small study, it had focused on just 11 boys and one girl with autism. Led by a surgeon in England, Andrew Wakefield, this study linked autism in these kids to their having gotten the MMR vaccine.

That 1998 study had not been performed well. Later research would show this. That didn’t stop parents around the world from panicking over its claims, however.

Many scientists also were concerned about the claims by Wakefield’s group. Some of them tried to repeat the study. But they didn’t get the same result. Much larger studies investigated further. They, too, failed to find support for the claim made by Wakefield’s team. More than that, research turned up evidence that Wakefield committed fraud. A series of articles published in BMJ, a British medical journal, outlined much of the evidence for that in 2011.

Despite all of this, the 1998 study’s claims have mushroomed online. One 2016 study in the Journal of Communication in Healthcare found nearly 500 anti-vaccine websites. The study’s authors looked at tactics used by different websites. Fear of autism is a big theme, thanks to the now-discredited study, it found. Some websites even cast Wakefield as a victim. Those websites dismissed or excused the big problems with his report.

Other websites included vague appeals to readers’ values or emotions. Some sites argued for individual freedom of choice. Those arguments don’t mention that public health and safety laws protect everyone. Other websites fostered distrust of doctors and companies that make vaccines. They did not point out that parents will need both doctors and vaccines if children get sick. Still other sites suggested that vaccines were somehow toxic or not “natural.” They ignored the fact that preventable diseases are “natural” — yet can still be deadly.

“Unfortunately,” says Peter Hotez, “anti-vaccine misinformation media dominates the internet.” Hotez is a pediatrician and vaccine scientist in Houston. He works at Baylor College of Medicine and at Texas Children’s Hospital.

Bogus findings

Sometimes when scientists can’t replicate, or reproduce, another study’s findings, it’s because someone made a mistake. But Wakefield’s group didn’t just make mistakes, scientists would find. And the 1998 study wasn’t just false. It was “fraudulent,” editors of BMJ would later report.

In January 2010, a government panel in the United Kingdom announced that it had found many problems with the 1998 study. Wakefield, for example, had gotten money from lawyers involved in lawsuits against the companies that make vaccines. That’s considered a “conflict of interest.” Wakefield also was charged with picking and choosing data to show what he wanted. That reflected poor study design. Evidence also showed that the team had fudged data — changed them to make them say what Wakefield wanted. Beyond that, there were ethical problems with how Wakefield’s team had gotten data on the children.

Wakefield lost his medical license. And The Lancet retracted his group’s paper in February 2010. Scientific journals have since become more attentive to signs of potential fraud.

Yet the damage from Wakefield’s work continues. Many parents still refuse to vaccinate their children because of his team’s initial claims.

“I see your pain [and] your desire for answers to your children’s health problems,” said Washington State Secretary of Health John Wiesman. He made this comment as an aside to parents of children with autism during a March 5 congressional hearing in Washington, D.C. But the answer is not to refuse vaccines, Wiesman stressed.

In the end, says Hotez, there is no link between vaccines and autism. That complex brain condition starts during pregnancy — long before anyone gets vaccines, he notes.

Hotez wrote about many more studies confirming the lack of any vaccine link to autism in a 2018 book. It’s about own adult daughter, Rachel, who has autism. And the title sums up what all the studies show: Vaccines Did Not Cause Rachel’s Autism.

Kathiann Kowalski reports on all sorts of cutting-edge science. Previously, she practiced law with a large firm. Kathi enjoys hiking, sewing and reading. She also enjoys travel, especially family adventures and beach trips.

Stephen Ornes lives in Nashville, Tenn., and his family has two rabbits, six chickens and a cat. He has written for Science News Explores since 2008 on topics including lightning, feral pigs, big bubbles and space junk.

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