In November 2025, the Centers for Disease Control and Prevention (CDC) updated its website on vaccine safety, declaring that “studies have not ruled out the possibility that infant vaccines cause autism.” That remarkable pronouncement was made despite the fact that experts have studied the supposed link for decades without finding any evidence to support it. There’s no legitimate controversy here. Vaccines are safe and effective. Here’s how a single, deeply flawed paper ignited the longstanding myth that vaccines cause autism, and how rigorous follow-up research has conclusively debunked it.
A story of bad science
To understand the history of the false connection between vaccines and autism, you have to go back to 1998. That’s when gastroenterologist Andrew Wakefield and several colleagues at the Royal Free Hospital and School of Medicine in London published a paper called “Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children.” The paper appeared in The Lancet, one of the most prestigious academic journals in medicine.
The paper presented the cases of 12 children with symptoms of autism who had received a vaccine against measles, mumps, and rubella (MMR). The children had been admitted to the gastroenterology ward at the Royal Free Hospital for tests that included spinal taps, MRIs, and scans and tissue samples of their gut lining. The researchers’ theory: Autism is a consequence of inflammation in the intestines caused by the MMR vaccine.
But the paper was flawed. Seriously flawed.
“The biggest problem was that it was ever published,” says Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “It was like the White Queen from Through the Looking-Glass, asking you to imagine six impossible things before breakfast.”
For starters, the number of children in the paper was tiny.
And there was no control group. So Wakefield and his colleagues could not compare kids who had received the MMR vaccine to those who had not to see if autism diagnoses differed between the two groups.
According to an investigative report published in the journal The BMJ by journalist Brian Deer in 2011, there were also serious problems with how the data in the Lancet paper were reported. For example, Wakefield described 10 of the 12 children in the paper as having a diagnosis of either autism or autism spectrum disorder. But four of the 10 had no record of ever having been diagnosed.
What’s more, the paper’s reports of autism symptoms in most of the children didn’t line up with their medical records. Wakefield described eight children as showing symptoms of autism within two weeks after receiving the MMR vaccine, but none of their records confirmed that timing. In fact, for the children whose medical records noted when their symptoms began, it was either before the vaccine or more than two weeks after. That was inconsistent with the authors’ conclusions that the children showed immediate changes after the vaccine.
What about the tissue samples Wakefield had gathered to demonstrate that the MMR vaccine caused intestinal inflammation? After experts at his own hospital reviewed the samples, they found that they were largely normal, identifying just one child who might have had bowel disease.
Of course, the researchers had no clear reason to investigate vaccines in the first place.
“You might as well have studied children who had recently eaten a peanut butter and jelly sandwich who developed symptoms of autism,” says Offit.
So why did Wakefield focus on vaccines? One possible explanation that journalist Brian Deer uncovered: In 1997, a year before his paper was published, Wakefield had filed a patent application for his own competing MMR vaccine. What’s more, according to Deer’s BMJ report, Wakefield had been contacted in 1996 by Richard Barr, an attorney who had worked with an anti-vaccine group. Barr was on the hunt for a researcher who could link vaccines with autism, which would strengthen Barr’s case against vaccine manufacturers in court. Barr’s law firm paid Wakefield £150 an hour (roughly $400 in 2026 dollars) for his “research.”
On top of that, “some of the families of the children enrolled in the paper were in the midst of suing pharmaceutical companies for damages due to injuries they said were caused by vaccines,” says Offit.
Wakefield’s impact
“There was tremendous skepticism of Wakefield’s paper,” says Offit. In fact, two CDC scientists who were working on vaccine safety described their concerns about Wakefield’s methods and conclusions in the same issue of The Lancet, noting that because “vaccines are given to millions of healthy people, usually infants, extremely high standards for vaccine safety are demanded.” They pointed out some of the problems with Wakefield’s paper and warned that “vaccine-safety concerns such as that reported by Wakefield and colleagues may snowball into societal tragedies” when the public avoids vaccines as a result.
That was in 1998. And snowball they have. In 2000, measles was declared “eliminated” in the United States. In 2025, largely due to outbreaks in Texas, South Carolina, Arizona, and Utah, there were more than 2,200 confirmed cases of the highly contagious disease. In just the first two months of this year, there were more than 1,100.
Despite the obvious flaws in Wakefield’s work, it would take more than a decade before he faced any consequences. In 2010, Wakefield was found guilty of professional misconduct by the General Medical Council, the group that sets standards for medical care and holds doctors in the United Kingdom accountable. The Council found that he had abused his position and subjected the children in his research to invasive tests (including spinal taps) that were not medically necessary. The Council also revoked Wakefield’s license to work as a doctor in the UK.
Wakefield’s paper was finally retracted in 2010. But the damage had been done. The myth that vaccines cause autism had spread far and wide, embedding itself in the collective consciousness.
Vaccines don’t cause autism
Wakefield’s paper was a case series, a type of study that reports on a group of patients who share a similar diagnosis or outcome. Case series don’t include comparison groups, so scientists don’t use them to draw conclusions about the causes of a disease. Instead, case series’ findings often prompt researchers to investigate something further.
Indeed, after Wakefield’s article was published in 1998, other researchers started to look into the potential link between vaccines and autism. Long story short: They found nothing to support Wakefield’s claims.
For example, in a study published in 2002, researchers examined the medical records of all 537,303 children born in Denmark between 1991 and 1998. Of those children, 440,655 had received the MMR vaccine and 96,648 had not. The researchers found no difference in the rate of autism diagnoses between the two groups. They concluded that their study “provides strong evidence against the hypothesis that MMR vaccination causes autism.”
And a 2014 analysis of five studies (including the one from Denmark) that followed more than 1.2 million children for an average of eight years also found no connection between vaccines and autism.
Despite all that solid evidence, the fear that Wakefield incited hasn’t gone away. In fact, it continues to grow.
The bottom line
Wakefield’s debunked paper caused enormous damage, but the evidence has been clear for decades. Vaccines don’t cause autism.
