The CDC is lying to you about vaccines and autism

The CDC is lying to you about vaccines and autism

The CDC is lying to you about vaccines and autism.

The CDC is lying to you about vaccines and autism.

If it bothers you that I sound, for the moment, like an antivax website c.2008 or an antivax Facebook or Twitter account c. 2015—or an antivax Tik Tok or X influencer just a week ago, just be aware that last Wednesday or Thursday, a mere five days ago, the next shoe dropped when it comes to Health and Human Services Secretary Robert F. Kennedy Jr.‘s continuing war on vaccines. That’s because, on November 19, 2025, the CDC updated its webpage about one of the central antivax claims dating back to the 1990s, the false claim that vaccines cause autism, a claim that originated in efforts in the 1990s by barristers to sue vaccine manufacturers on behalf of parents of autistic children that culminated in Andrew Wakefield’s fraudulent 1998 Lancet case series linking the MMR vaccine to autism. Here’s what I mean. Take a look screenshots of the last version of the webpage saved in the Internet Archive’s Wayback Machine before the change (an archive of the page when it was last updated on December 31, 2024 captured on October 11, 2025) and the webpage as it appears today:

Let’s compare. First, here are the CDC’s key points about vaccines and autism before November 19:

• Studies have shown that there is no link between receiving vaccines and developing autism spectrum disorder (ASD).
• No links have been found between any vaccine ingredients and ASD.

Both of these are true, and the page goes on to describe why they are true, as well as to look at supporting evidence that neither vaccination nor any vaccine ingredient has been associated with an increased risk of autism in large, well-designed, well-executed epidemiological studies. It is a point that we here at SBM have discussed more times than I can remember going back to the very beginning of this blog in 2008 and that I myself have discussed going back to early 2005 on my not-so-super-secret other blog, in particular how antivaxxers publish bad science and misrepresent the scientific literature to try to cast doubt on that. Indeed, I just wrote such a post about a recent misleading and terrible “report” claiming that a link is plausible a mere two weeks ago. (More on that later, as it is relevant to the CDC’s rewriting of its webpage on vaccines and autism.)

Now, here are the CDC’s misleading key points that lie to you about vaccines and autism:

• The claim “vaccines do not cause autism” is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.
• Studies supporting a link have been ignored by health authorities.
• HHS has launched a comprehensive assessment of the causes of autism, including investigations on plausible biologic mechanisms and potential causal links.

You might wonder why the first heading still reads, “Vaccines do not cause autism.” The new webpage explains:

The header “Vaccines do not cause autism” has not been removed due to an agreement with the chair of the U.S. Senate Health, Education, Labor, and Pensions Committee that it would remain on the CDC website.

Yes, as part of the deal that garnered him critical support for his nomination, RFK Jr. promised Sen. Bill Cassidy, the physician-politician and chair of the Senate HELP Committee who betrayed his Hippocratic oath twice, first to send RFK Jr.’s nomination for HHS Secretary to the full Senate and then to vote for his confirmation, that the CDC webpage continue to say that vaccines don’t cause autism. Of course, what has really happened is that RFK Jr. has broken his pledge not to change CDC messaging on vaccines and autism because he put an asterisk next to the statement that vaccines do not cause autism and then added all sorts of antivax propaganda after it. Truly, when I consider Sen. Cassidy’s cowardly and perfidious betrayal and his ongoing attempts to “control” RFK Jr., I’m reminded of this cartoon:

Let’s take these points on one at a time. Why start with the last point? Because it’s one part of the strategy by which RFK Jr. has been preparing the way to force the CDC to pivot to messaging that, at the very least, will ignore three decades worth of scientific evidence failing to find a hint of a whiff of a correlation between infant and childhood vaccination and autism risk in favor of bad science by ideologically motivated antivaxxers claiming a link to falsely portray a link as at least plausible or, at worst, proclaim that the aforementioned bad science by ideologically motivated antivaxxers claiming a link demonstrates that there is a link. Here are key components the strategy designed to cast doubt on vaccines:

• Falsely argue that the science showing no link between vaccines and autism is uncertain and that therefore a link is still scientifically plausible.
• Bolster the deceptive claim that a link between vaccines and autism is plausible through wild speculation about biological mechanisms.
• Falsely argue that vaccines are inadequately tested clinically and epidemiologically; e.g., through the deceptive claim that vaccines aren’t tested against “saline placebo.”
• Manufacture evidence through bad science that vaccines are actually associated with autism.

I’ll start with the last CDC talking point (“HHS has launched a comprehensive assessment of the causes of autism”), because I’ve written about it before and it’s fairly quick. Then I’ll discuss the other two points, how antivaxxers are now gloating and proclaiming victory, and where this all fits in when it comes to RFK Jr.’s ongoing efforts to eliminate all vaccines. (And, yes, the elimination of vaccines in the US is his endgame, no matter how many times he lies and claims that he doesn’t want to take away people’s vaccines or that he’s all about “personal choice,” “informed consent,” and “health freedom,” and falsely reassures people that they will be able to be vaccinated (and to vaccinate their children) if they desire.

Again, let me emphasize to you: The CDC is lying to you about vaccines and autism, and this change in CDC messaging is part of a strategy to sow doubt and fear about vaccines in order to allow him to succeed in taking away your vaccines.

“HHS has launched a comprehensive assessment of the causes of autism”? More like the same ol’ same ol’ repackaged and made official policy

My first reaction to this statement was that it was typical of the way cranks and quacks misrepresent science. How? Basically, it frames its new “comprehensive assessment” as though it were something new, as though scientists hadn’t been diligently researching the causes and potential treatments for autism for, quite literally, decades and already know that autism is largely genetic. Moreover, antivaxxers like RFK Jr. are so focused on vaccines as The One True Cause of autism that they ignore the simple fact that arguably the single most-studied potential cause of autism has been—surprise!—vaccines. And guess what? Numerous large, well-designed studies from different countries and different designs have failed to find an association between childhood vaccination and an increased risk of autism. Let’s move on, though, to what, exactly, RFK Jr.’s “comprehensive assessment of the causes of autism” is likely to entail and who will be doing the “research.”

Regular readers (and anyone paying attention to RFK Jr.’s “stewardship” of HHS probably remember that in April he launched an effort to find the causes of autism and, remarkably, promised to have results by September. In the meantime, he hired a veritable rogues’ gallery of antivaxxers to work on this question, starting with (as far as we know) David Geier, the son half of the father-son quack duo who blamed the mercury in the thimerosal preservative that used to be used in several childhood vaccines until around 2001 for an autism epidemic and ran a quack clinic and mail order pharmacy that claimed to treat autism with chelation therapy and puberty blockers, with David Geier being prosecuted for practicing medicine without a license. Unsurprisingly, Dr. Mark Geier (recently deceased) was a frequent expert witness for complainants to the Vaccine Court back in the day. Evidence of Mr. Geier’s “skills” at epidemiological research came from his violating the protocol approved by the institutional review board overseeing his proposed use of Vaccine Safety Datalink data to look for links between vaccines and autism in 2003. Now he’s likely to do the same, just as an official employee of the NIH.

Joining Geier was Mark Blaxill, a longtime antivax activist with no medical training who was also hired at the CDC as a senior advisor. Author of The Age of Autism: Mercury, Medicine, and a Man-Made Epidemic with fellow antivaxxer and blogger Dan Olmsted, Blaxill served for a long time on the board of directors of the group of the antivax group SafeMinds and had a penchant for Holocaust analogies referring to vaccination and autism. One of its most famous publications was an article entitled Autism, A Novel Form of Mercury Poisoning, published in 2001—in Medical Hypotheses, naturally. Blaxill was also associated with another antivax group, Generation Rescue, and wrote prolifically for its blog, Age of Autism, a frequent source for my blogging “inspiration” back in the day. There, Blaxill wrote posts like There’s a Funny Thing About Evidence: More Support for Autism-Mercury Link whose misinformation, bad science, and pseudoscience I routinely used to lovingly deconstruct years ago.

That’s not all. Another antivax hire was Dr. Tracy Beth Høeg, who was hired as a top advisor to Dr. Marty Makary, who is currently FDA Commissioner, who had also become famous as a “COVID-19 contrarian” and slipped further and further into COVID-19 vaccine “skepticism” as the pandemic wore on. Working for Dr. Makary is also Dr. Vinay Prasad, an oncologist and COVID-19 “contrarian” who eventually turned to parroting antivax talking points and is now in charge of the FDA committee responsible for approving and regulating vaccines and biologics. In addition, don’t even get me started on what RFK Jr., did with the CDC Advisory Committee on Immunization Practices (ACIP). There, he fired all the experts on the committee, replaced them with antivaxxers and antivax-adjacent or -sympathetic new members, resulting in a clown car of a spectacle as ACIP incompetently tried to roll back current vaccine recommendations and made an incoherent mess of recommendations for COVID vaccines. Interestingly, this effort has failed to satisfy RFK Jr.’s most vehement supporters, and the most that RFK Jr.’s new effort to prove that vaccines cause autism came up with in September was a highly dubious claim that acetaminophen use during pregnancy is associated with autism. (It’s not.)

So what is HHS going to do under RFK Jr.? According to the newly rebranded antivax CDC webpage:

HHS will evaluate plausible biologic mechanisms between early childhood vaccinations and autism. Mechanisms for further investigation include the impacts of aluminum adjuvants, risks for certain children with mitochondrial disorders, harms of neuroinflammation, and more.

Regular readers will recall that all of these “plausible biological mechanisms” are actually not so plausible. Indeed, a lot of them are based on what I like to call “biobabble” or “immunobabble,” names that I came up with in homage to “technobabble,” a term used to describe a lot of the futuristic science-y sounding dialogue about physics, biology, and other sciences in Star Trek: The Next Generation and later series. (Public health scientist Jess Stier and colleagues amusingly coined a term for the same phenomenon, “antivaccine Mad Libs.”) Basically, antivaxxers love to do the same sort of speculative handwaving about biological mechanisms behind autism that they think they can relate to vaccines, using the sort of language that real scientists immediately recognize as fancy sounding scientific bullshit.

Indeed, this brings me back to the report that I mentioned in the introduction. Known as the McCullough Foundation Report, it was published in late October and widely debunked by many, including myself, for exactly this sort of speculative handwaving based on interpretations of basic science findings that have consistently failed to be demonstrated in clinical and epidemiological studies to be applicable in humans to the neurodevelopmental mechanisms that lead to autism. It’s a longtime antivax technique, and there are a number of “tells” in the paragraph above that let me know that this is what the CDC is doing now, in particular invocation of mitochondrial disorders (shades of Hannah Poling and Andrew Zimmerman in 2008!), adjuvants like aluminum (which do not cause autism), and use of the term “neuroinflammation.” These were “mechanisms” featured prominently in the McCullough Report.

In other words, this research effort being carried out by HHS agencies such as the National Institutes of Health and the CDC is nothing more than using antivax pseudoscientific ideas as the basis to design research programs to manufacture bogus scientific data to support the idea that vaccines cause autism.

“The claim ‘vaccines do not cause autism’ is not an evidence-based claim”? Wrong.

Let’s circle back to first new CDC talking point, namely that the claim “vaccines do not cause autism” is not an evidence-based claim “because studies have not ruled out the possibility that infant vaccines cause autism.” This is a complete misrepresentation or intentional misunderstanding of how evidence-based medicine—and science in general—works. It is not my intention here to relitigate the mountains of scientific evidence this century that have failed to find conclusive—or even convincingly plausible—scientific, epidemiological, or clinical evidence that infant vaccines detectably increase the risk of autism, much less cause autism. I’ve discussed that evidence and antivax attempts to attack it more times than I can remember. There are many good reasons why the statement that vaccines do not cause autism is considered very strong science by the scientific community, sufficiently strong that most scientists studying autism and vaccines consider the issue to have been scientifically settled, at least pending new and compelling evidence suggesting a link, evidence that antivaxxers can never seem to produce. Indeed, a large chunk of posts on this very blog are deconstructions of the sort of bad science that antivaxxers routinely produce to try to “prove” that vaccines cause autism; e.g., this study in 2017.

Instead, let’s address the bogus argument that the claim that “vaccines do not cause autism” is not evidence-based, specifically because “because studies have not ruled out the possibility that infant vaccines cause autism.” It’s an argument that is often weaponized in favor of alternative medicine quackery, such as the scientific conclusion that homeopathy is physically impossible. What I like to say in response to such arguments about homeopathy is that science can never absolutely prove a negative. That’s just not how science works. However, after a certain point, the weight of scientific studies reaches a point where the odds that the negative finding is incorrect becomes so small as to be, for all practical purposes, functionally and statistically indistinguishable from zero.

Such has long been the scientific status of, for example, homeopathy, with the added bonus that the mechanisms proposed by homeopaths for homeopathy to “work” would, if true, require that huge swaths of long-settled physics, chemistry, and biology be not just wrong, but spectacularly wrong. Similarly, the evidence from large studies looking for links between infant vaccination and autism have failed to detect an increased risk of autism attributable to vaccination or to specific ingredients in vaccines, such as thimerosal (which is no longer in childhood vaccines and hasn’t been in vaccines for close to a quarter of a century) or aluminum salts used as adjuvants. I will conceded that biological mechanisms proposed by antivaxxers for vaccines to cause autism are not quite as fantastical as the claimed mechanisms behind homeopathy, but they’re still incredibly implausible. (Does anyone remember “molecular mimicry” and “homologous recombinaltion tiniker“?)

This is where the twin strategies of casting doubt on existing evidence because studies haven’t examined every possible scenario. As Matthiew Facciani put it on Threads:

I mean, seriously: Do dogs cause autism?

This is all, of course, basically a rephrasing of what I’ve long written, but in simpler terms, which is why I quoted it. Again, the weight of evidence that fails to find even a hint of a whiff of an association between infant and child vaccination and increased autism risk is enormous, so enormous that, even though we can never prove that the chances that vaccines cause autism in anyone is truly zero, we can conclude from the evidence that this chance is so small that it is, for all intents and purposes, functionally indistinguishable from zero. That is what the science shows, and that is why scientists say that vaccines do not cause autism.

Think of the change in wording on the CDC webpage on vaccines and autism as being very similar in intent to the frequent claim by RFK Jr. that most childhood vaccines have never been subjected to randomized controlled clinical trials versus a saline placebo, a claim that RFK Jr.’s antivax propagandist bud Del Bigtree was touting this weekend on X, the hellsite formerly known as Twitter:

I’ve discussed in depth why this claim is deceptive. I’m not going to discuss why in detail here because I’ve already discussed it multiple times, most recently here (where I described why the “no saline placebo” claim is deceptive nonsense that doesn’t show that vaccines are unsafe) and here (where I discussed how RFK Jr.’s HHS has deceptively weaponized and misapplied the principles of evidence-based medicine, ignoring medical ethics, to cast doubt on vaccines and justify making influenza and COVID-19 boosters much more difficult to approve.

Again, what RFK Jr. is about is not science. It is not about medicine or public health. It’s about spreading doubt about the safety and efficacy of vaccines as a prelude to regulating them out of existence in the US. It’s no different than the “toxins” gambit antivaxxers used to love to employ back around 2008, blaming formaldehyde (present in trace amounts in some vaccines) and the like for autism. Every time a study exonerated one vaccine ingredients, antivaxxers would shift to others to blame for autism. I used to like to say that “aluminum is the new mercury” because, after studies increasingly exonerated mercury in vaccines as a cause of autism, antivaxxers just shifted to blaming aluminum adjuvants. Either that, or they shifted to “too many too soon,” the “hypothesis” that it is the overall vaccine schedule that “overloads” the infant immune system and somehow causes autism. Basically, every time science falsifies an antivax “hypothesis” or shows that a proposed scientific mechanism by which antivaxxers claim that vaccines cause autism, they easily and seamlessly shift to another, more elaborate hypothesis or mechanism that is more difficult to falsify. Indeed, citing unfalsifiable hypotheses is an antivax specialty, as noted by Kristen Panthagani:

After three decades of research into the topic, with shifting rumors and scientists doing more and more research trying to keep up, the rumor has still not been satisfied. Now the rumor’s demands have shifted again — “but have you studied every vaccine ever?” “What about the entire childhood vaccine series altogether?” If scientists spend the next ten years painstakingly performing these giant studies, the rumor would likely shift yet again — “ok but you added more vaccines to the childhood vaccine schedule, have you checked the updated childhood vaccine schedule?” “What about this vaccine and this specific subtype of autism?  “What about parents who got the COVID vaccine?” “What about moms who got multiple vaccines during pregnancy?” “What about these specific vaccine ingredients during pregnancy?” “You’ve only done observational studies looking into these 17 questions, where are the randomized controlled trials?” We could go on and on forever like this, creating unending list of questions and demands.

This is what antivaxxers do. It’s what they’ve been doing ever since I started really paying attention to them two decades ago.

As noted in an NPR article on the change in the CDC webpage:

“The Centers for Disease Control and Prevention website has been changed to promote false information suggesting vaccines cause autism,” said Dr. Susan J. Kressly, president of the American Academy of Pediatrics, in a statement. “Since 1998, independent researchers across seven countries have conducted more than 40 high-quality studies involving over 5.6 million people. The conclusion is clear and unambiguous: There’s no link between vaccines and autism.”

And:

“The new statement shows a lack of understanding of the term ‘evidence,’” the Autism Science Foundation said in a statement the organization provided to NPR, adding, “No environmental factor has been better studied as a potential cause of autism than vaccines.”

Quite so. The single most-studied environmental factor as a potential risk factor for or cause of autism is undeniably vaccines, and the studies have consistently come up negative for a detectable association dating back nearly three decades. The way antivaxxers have gotten around that simple fact about the science is by continually misrepresenting the evidence base and shifting the goalposts when science falsifies one of their fanciful hypotheses.

“Studies supporting a link have been ignored by health authorities”

I realize now that I should have dealt with this claim sooner, because, really, it’s fairly obviously bullshit. Scientists haven’t “ignored” studies supporting a link between vaccines and autism. They’ve read them, evaluated them, and recognized them as poorly designed and executed studies that do not demonstrate what antivaxxers claim that they demonstrate. Moreover, as I’ve frequently argued, scientists would not have persisted in doing study after study after study looking for links between vaccines and autism, persisting in doing more studies long after the vast preponderance of evidence had long ago shown that the likelihood of ever finding such a link was functionally no different than zero, were it not in service of a hopeless attempt to reassure hard core antivaxxers that vaccines do not cause autism. I can’t help but also mention that, every time such studies are published, antivaxxers are not reassured and instantly do their damnedest to cast doubt on each study, even if they have to attribute dubious methodological shortcomings to each study in order to convince themselves. Again, I’ve written about such attacks more times than I can remember over the last 20 years.

This HHS claim that the “studies are being ignored” is, at its heart, basically nothing more than the central conspiracy theory of the antivaccine movement, namely that the “evidence is out there” that vaccines cause autism by “They” (a cabal of scientists, physicians, Big Pharma, the CDC, the FDA, etc.) are “covering up” the real data and evidence. In essence, this statement is nothing different from what RFK Jr. wrote over two decades ago in Deadly Immunity, when he proposed a conspiracy theory that the CDC really did have the evidence that the mercury-containing preservative thimerosal that used to be in several childhood vaccines was the cause of the “autism epidemic” and convened a meeting at the Simpsonwood Conference Center in suburban Atlanta in 2000 to find a way to cover it up. It’s no different from the more recent “CDC whistleblower” conspiracy theory that claimed that the CDC had evidence that vaccines were associated with a higher risk of autism in African-American boys but had “covered it up.” As I like to say, all science denial, antivax vaccine denial included, is a conspiracy theory.

As Dr. Peter Hotez put it:

Attacking scientists as dishonest and corrupt comes straight out of the anti-vaccine playbook, said Peter Hotez, MD, codirector of the Texas Children’s Hospital Center for Vaccine Development, who also helped develop an affordable, unpatented COVID-19 vaccine.

“This is how the wellness influencer industry works,” Hotez said. “It’s not enough to push the snake oil. You have to discredit mainstream biomedical science and portray scientists as public enemies or cartoon villains, and that’s what Kennedy’s seeking to do.”

Now the antivax arch-conspiracy theorist RFK Jr. is in charge of HHS, and the CDC is well on its way to becoming, as we had feared after RFK Jr. bent the knee to Donald Trump in the lead-up to the 2024 election, an antivax propaganda outfit.

The CDC is lying to you and is no longer reliable

Unsurprisingly, antivaxxers are beside themselves with joy and celebration with the change in messaging on vaccines and autism from the CDC. For example:

CHD, as you recall, is an antivax organization founded by RFK Jr. Elswhere, here are some samplings of the rejoicing from around the antivax influencer crankosphere:

I could provide many more examples, but I think you get the idea. The gloating and rejoicing on the antivax side are truly epic. It also makes me wonder if the growing dissatisfaction with RFK Jr. expressed by antivaxxers over their perception by ardent antivaxxers that he hasn’t done much on vaccines also prodded him to make this change.

I never thought I’d be writing these words, much less repeating them several times in a single post, but the CDC is lying to you. It can no longer be considered a reliable source of information about vaccines. Nor, depressingly, am I alone in concluding that:

Instead of a global leader in science, the CDC has devolved into “a propaganda machine for RFK Jr.’s fixed, immutable, science-resistant theories,” said Paul Offit, MD, an infectious disease specialist at Children’s Hospital of Philadelphia and co-inventor of the rotavirus vaccine. “The CDC is being weaponized to promote RFK Jr.’s anti-vaccine point of view. So why should you trust it?”

Many public health experts who spoke to CIDRAP News sounded sorrowful.

“Today is a tragic day for public health, for the US government,” said Michael T. Osterholm, PhD, MPH, director of the University of Minnesota’s Center for Infectious Disease Research and Policy (publisher of CIDRAP News). “Ideology has replaced science as the means for addressing life-saving research and best practices that save lives.”

Many physicians worry that the CDC’s new message will dissuade parents from vaccinating their children.

That is, of course, exactly RFK Jr.’s intent. Meanwhile, those who remain behind at CDC are increasingly demoralized and traumatized as the describe the changes to the CDC webpage as “embarrassing” and “horrifying”:

While they declined to be identified for fear of retaliation, they all said that they and their colleagues were shocked and dismayed by the misinformation put forth on the new page. “It’s horrifying, it’s embarrassing, it’s scary, it’s heartbreaking—it’s all of those things,” said a staffer at the CDC’s Injury Center. “To see our agency being used to spread lies and misinformation is a gut punch,” a CDC communicator with the National Center for Immunization and Respiratory Disease wrote in a message. “People will be harmed by this—parents will decide not to vaccinate their kids because of false information, and kids will get sick and die as a result.”

Another longtime CDC employee who works in communications said, “The best way I can put it is it feels like we’re on a hijacked airplane.”

This is, of course, the intent, to make CDC scientists and staff who try to stand up for vaccine science feel so demoralized and hopeless that they leave, so that they can be replaced by antivax-compliant “scientists.”

As for my statement that we can no longer trust the CDC for reliable information on vaccines under RFK Jr.:

When asked if the CDC was still a reliable source of public-health information, the employees said that most of the public-facing information remained unchanged. A critical problem was that there didn’t appear to be a good way for the public to discern the difference between accurate and politicized messaging. “I don’t know how they would distinguish that,” the Chronic Center staffer said. “There’s not a disclaimer saying posts were approved by political appointees and not by career scientists, so I don’t know.”

“It’s really easy from inside the agency to know what is real information and what has just been added there for political reasons,” added the longtime communications staffer. “But I can see that it would be really hard if you’re outside the agency to know the difference.”

Again, that’s the intent. It’s all coming from the CDC, the remaining reliable information and the ideological antivax propaganda. I can tell the difference, but how on earth is the average person without scientific training going to be able to tell the difference? Even some doctors who don’t have the experience of two decades of refuting antivax lies that I have accumulated might have difficulty telling the difference in some cases.

As I have been warning, RFK Jr. is coming for your vaccines. Eliminating vaccines is his endgame. It’s always been his endgame. What he’s done with ACIP and the FDA are just steps along the way. This change to a major CDC webpage on vaccines and autism is yet another part of RFK Jr.’s ultimate plan to eliminate vaccines.

And Sen. Bill Cassidy bears huge responsibility putting RFK Jr. in a position where he can potentially achieve his aim.