Two decades ago, an esteemed medical journal published a small study that has become one of the most notorious and damaging pieces of research in medicine.

The study, led by the now discredited physician-researcher Andrew Wakefield, involved 12 children and suggested there’s a link between the measles, mumps, and rubella vaccine — which is administered to millions of children around the world each year — and autism.

The study was subsequently thoroughly debunked. The Lancet retracted the paper and Wakefield was stripped of his medical license. Autism researchers have shown decisively again and again that the developmental disorder is not caused by vaccines.

Still, public health experts say the false data and erroneous conclusions in that paper, while rejected in the scientific world, helped fuel a dangerous movement of vaccine skepticism and refusal around the world.

Since its publication, measles outbreaks have erupted in Europe, Australia, and the US in communities where people refuse or fear vaccines. Vaccine refusal has become such a problem that some countries in Europe are now cracking down, making vaccines mandatory for children and fining parents who reject them. In 2019, the World Health Organization called vaccine hesitancy one of the top threats to global health.

But there’s more to the story. While the WHO’s 2015 target to eliminate measles has not yet been met, and a recent spike in measles cases is concerning, progress against the disease has continued globally. The publication of yet another major study debunking the vaccine-autism link, on March 5 in the Annals of Internal Medicine, seems like a good moment to look back at what fueled the vaccine concerns, and consider how we can prevent other ideas harmful to public health from taking hold.

The MMR vaccine-autism study was dubious science

The first thing to know about Wakefield’s paper is that it was very dubious science. It did not deserve to be published in a top-tier medical journal — let alone receive all the attention it has subsequently gotten.

Wakefield drew the association between the measles-mumps-rubella (MMR) vaccine and autism based on a study involving only 12 children.

The paper was also a case report. Case reports are detailed stories about particular patients’ medical histories, and — because they are basically just stories — they are considered among the weakest kinds of medical studies. To be sure, these reports can be useful, but they are certainly not the evidence on which you want to make bold claims about something like the vaccine-autism link.

Many children have autism and nearly all take the MMR vaccine. Finding in this case that among a group of a dozen children most of them happen to have both is not at all surprising. And it in no way proves the MMR vaccine causes autism. (Wakefield also proposed a link between the vaccine and a new inflammatory bowel syndrome, which has since been called ”autistic enterocolitis” and has also discredited.)

What’s more, when British investigative journalist Brian Deer followed up with the families of each of the 12 kids in the study, he found, “No case was free of misreporting or alteration.” In other words, Wakefield, the lead author of the original report, manipulated his data. (See the pop-up chart in this report for details.)

Wakefield also had major financial conflicts of interest. Among them, while he was discrediting the combination MMR vaccine and suggesting parents should give their children single shots over a longer period of time, he was conveniently filing patents for single-disease vaccines. Even more absurdly, the General Medical Council (the UK’s medical regulator) found that he had paid children at his son’s 10th birthday party to donate their blood for his research. (In deciding to take away his UK medical license, the GMC said Wakefield acted with “callous disregard for the distress and pain the children might suffer.”)

Finally, Wakefield never replicated his findings. At the very bedrock of science is the concept of falsification: A scientist runs a test, gathers his findings, and tries to disprove himself by replicating his experiment in other contexts. Only when that’s done can he know that his findings were true.

As the editor of the BMJ pointed out, “Wakefield has been given ample opportunity either to replicate the paper’s findings or to say he was mistaken. He has declined to do either.” In 2004, 10 of his co-authors on the original paper retracted it, but Wakefield didn’t join them, and he has since continued to push his views, including doing the rounds on the anti-vaxxer speakers’ circuit and publishing books.

The vaccine-autism link has repeatedly been debunked

In the most recent analysis, published March 5 in the Annals of Internal Medicine, researchers at the Statens Serum Institut in Denmark linked vaccine information to autism diagnoses, sibling histories of autism, and autism risk factors in more than 600,000 children born in Denmark between 1999 to 2010. “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,” the researchers concluded.

Before that, researchers writing in JAMA looked at nearly 100,000 children who got the shot and their family histories of autism. The researchers again found the MMR vaccine was not associated with an increased risk of autism, even with children who had older siblings with the disorder. “These findings indicate no harmful association between MMR vaccine receipt and ASD even among children already at higher risk for ASD,” the researchers concluded.

All together, the idea that the MMR vaccine may cause autism has been debunked by large-scale studies involving thousands of participants in several countries.

But the whole debacle isn’t only Wakefield’s fault

So how did such a shoddy idea gain such outsized influence? The second thing to know about Wakefield’s vaccine-autism study is that the media helped it go viral.

One of my favorite writings on the Wakefield debacle comes from the British journalist-researcher Ben Goldacre. In a column for the Guardian and in his book Bad Science, Goldacre pointed out that journalists were complicit in helping perpetuate the notion that vaccines cause autism:

Wakefield was at the centre of a media storm about the MMR vaccine, and is now being blamed by journalists as if he were the only one at fault. In reality, the media are equally guilty. Even if it had been immaculately well conducted — and it certainly wasn’t — Wakefield’s “case series report” of 12 children’s clinical anecdotes would never have justified the conclusion that MMR causes autism, despite what journalists claimed: it simply didn’t have big enough numbers to do so. But the media repeatedly reported the concerns of this one man, generally without giving methodological details of the research, either because they found it too complicated, inexplicably, or because to do so would have undermined their story.

We journalists are still doing this today on myriad health topics. We report on single, often poorly designed studies — even if they don’t deserve an ounce of attention. We also focus a lot more on the anti-vaccine movement and their concerns than on the astounding progress made against vaccine-preventable diseases.

Part of this has to do with how newsrooms work: Reporters favor anomalies and novelty instead of slow and plodding progress, as Steven Pinker points out in his recent book, Enlightenment Now. But in doing so, we lose sight of the big picture.

Vaccines, Pinker notes, have been critical to the progress we’ve made during the past century against death and disease. The discovery of a smallpox shot, for example, helped turn a gruesome and painful illness — which killed more than 300 million people in the 20th century — into a thing of the past. (Smallpox is the only disease in humans that’s been eradicated, with the last case turning up in Somalia in 1977.)

More recently, since 1990, childhood deaths from infectious diseases like HIV and measles (yes, measles!) have continued to decline around the world, thanks to both vaccines and infection control practices. Just look at this recent chart from the US Centers for Disease Control and Prevention:

It shows that measles deaths with vaccination have continued to drop around the world through the 2000s. “For the first time,” the report read, “annual estimated measles deaths were fewer than 100,000, in 2016.”

Measles cases in the US in recent years have held fairly steady since the disease was eliminated here in 2000 (meaning it’s no longer endemic). These days, outbreaks occur when travelers return to unvaccinated communities — like the 2014 outbreak among an unvaccinated Amish community in Ohio.

Again, the progress against measles happened because of routine immunization services becoming increasingly available here and abroad. Since 2000, some 5.5 billion doses of measles-containing vaccines have been given to kids, saving an estimated 20.4 million lives. So the most powerful contributor to the fight against vaccine-preventable diseases was science, Pinker reminds us. Let’s not lose sight of that by focusing too much on bad science.

But truly stopping the spread of dubious science will require a lot more than developing a more skeptical media. As I’ve written before, it must also involve thinking about how to prevent bad science from taking off in the first place by educating young people in critical thinking skills.

Creating armies of little bad science detectors — who can easily spot a shoddily designed study — is the only way to inoculate ourselves against another Wakefield debacle.