Over the weekend, Reuters reported that the Centers for Disease Control and Prevention is planning a large study looking into whether vaccination can cause autism. It’s a study that will be a complete waste of time and money, given how much scientific work has already been devoted to the topic.
The CDC is one of several agencies under the umbrella of the U.S. Department of Health and Human Services, now being run by Robert F. Kennedy Jr. Last December, then President-elect Donald Trump said that RFK Jr. would investigate the purported link between vaccines and autism spectrum disorder, claiming that “someone has to find out” what is causing the reported increase in autism cases. But in fact, many studies have already examined this very question, and the vast majority have failed to find any such connection.
Though the antivaccination movement has existed since the days of Edward Jenner and his first ever vaccine for smallpox in the early 1800s, the specific fascination with autism only picked up steam during the late 1990s. In 1998, British doctor Andrew Wakefield published a widely publicized study in The Lancet that suggested a link between autism and the measles, mumps, and rubella vaccine (MMR). Though the study only involved 12 children, early media coverage lent credibility to the findings, and may have convinced some people to avoid the MMR shots.
Even at the time, though, many other scientists were not convinced of Wakefield’s conclusions, and it didn’t take too long for contradictory data to emerge.
In 1999, for instance, a study of UK children failed to find any evidence of a causal link between autism and MMR vaccination. A 2002 study of all children born in Denmark during the 1990s found no association between the MMR shots and autism diagnosis; if anything, unvaccinated children appeared to have a slightly higher risk of autism. Another 2002 study of Finnish children found no link between MMR vaccination and autism or other serious neurological conditions. A 2006 study of Canadian children found no association between autism and the MMR vaccine or thimerosal, a mercury-based preservative once added to certain childhood vaccines (though never the MMR vaccine). A 2015 study of U.S. children also found no link to MMR vaccination, even in children whose older siblings have autism (meaning that the younger children may have been more genetically vulnerable to it). And a 2019 study of Danish children (conducted by some of the same authors as the 2002 study) again found no link between MMR and autism.
The rate of diagnosed autism has significantly increased over time. And it is possible that certain environmental risk factors, such as prenatal exposure to air pollution or more people having children at an older age, could be contributing to a genuine increase in autism cases. But many experts have argued that most of this rise is tied to an increased awareness of autism symptoms as well as broader criteria in how autism is diagnosed.
Dozens of studies have looked into a possible connection between vaccines or certain vaccine ingredients like thimerosal and autism, and nearly all have come to the same conclusion. Other studies have debunked assumptions behind this supposed link, finding that autism-related brain changes often begin in the womb. On occasion, you might hear of an apparent game-changing paper that says otherwise, though these papers tend to be written by people supportive of the anti-vaccination movement and are often quickly criticized for glaring methodological flaws by other researchers.
As it turns out, Wakefield’s original 1998 paper was fatally flawed as well. In 2010, The Lancet retracted the paper, citing the discovery of several “incorrect” elements. It was a retraction that followed the exhaustive investigative work of journalist Brian Deer. Among many other things, Deer found that Wakefield financially benefited from tearing down the MMR vaccine (more so if it was replaced by an individual measles vaccine he and others had patented), and that he fraudulently misrepresented the patient data described in his study.
Decades and countless resources have been spent chasing after Wakefield’s bogus wild goose. And there’s nothing to suggest that this planned CDC study will find anything substantial to overturn the overall evidence showing that vaccines do not cause autism. There’s also little indication that Kennedy will acknowledge his errors in suggesting a link, as he promised to during Senate hearings for his confirmation to HHS chief.
Though Kennedy has said that he is not an anti-vaccination proponent, he has repeatedly spread misinformation about vaccines for at least 20 years, including the debunked link to autism. And during the Senate hearings, Kennedy dismissed the notion of a broad scientific consensus on the issue, instead citing an isolated (and likely very flawed) recent study that said otherwise.
Should this study go ahead as planned, it would be the latest indication that the CDC and other agencies are heading down an unfortunate path, in which debunked myths, bad science, and conspiracy theories are allowed to enter as valid scientific debate.
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