Vaccines don't cause autism. Okay?

I’m not a doctor, but I play one in naughty fantasy sessions.

Still, that’s not quite enough for me to feel comfortable addressing the 10,000 e-mails I’ve received from readers in the past two days asking for a serious rebuttal to the anti-vaccination crowd, following news that a family of an autistic girl was compensated for damages caused by a vaccine. I do, however, want to state for the record that the anti-vaxxers are simply wrong. Vaccines have never, ever been shown to cause autism despite many large, carefully controlled studies.

When I have more time, I’d like to pull together a nice layperson’s guide to vaccination misconceptions. In the meantime, please go read what Orac has to say about the recent hullabaloo (is that a word? I think that’s a word). Amanda has posted another good link to Orac in her Quickies post today. Also, I’m sure that Steve will have plenty to say about it on next week’s edition of The Skeptics’ Guide. Have another good skeptical link addressing the issue? Please post it below.


Rebecca Watson

Rebecca leads a team of skeptical female activists at She travels around the world delivering entertaining talks on science, atheism, feminism, and skepticism. There is currently an asteroid orbiting the sun with her name on it. You can follow her every fascinating move on Twitter or on Google+.

Related Articles


  1. I know this is potentially a controversial thing to say, but I can't help thinking that even if there was a link between vaccines and autism, and even with the suffering that kids with autism and their families go through, that's better than the extraordinary child mortality rate we had before vaccines.

  2. Orac is a great resource for these sorts of things. He's very good at breaking these issues down for us non-doctorly types to digest.

    Oh, and yes, "hullabaloo" is a real word.

  3. There is zero actual evidence for vaccines causing autism, and especially for mercury in vaccines causing autism. There is considerable evidence that vaccines and mercury don't cause autism.

    Orac is an excellent resource, as is the autism hub.

    If you are interested in the nitric oxide connection to autism (what I think is the "real" cause), the only place you are going to find it is on my blog (so far).

    The discussion of how acute fevers resolve some of the symptoms of autism is a good place to start (but not for the faint-hearted, it is over 20 pages), but complex things can't be addressed in simple sound-bites. Be skeptical of those who try to do so (and also skeptical of those who don't).

  4. If you are interested in the nitric oxide connection to autism (what I think is the “real” cause), the only place you are going to find it is on my blog (so far).

    Oh joy, a crank in the making. If it walks like a duck…

  5. I’m a serious golf addict (who does not want to be cured) that admits to watching The Golf Channel. Last night I had to hear golf commentators blathering on about autism issues because of a golfer coming out about his son being diagnosed. It was the whole Thimerosal, it’s an epidemic, contact “Autism Speaks”, sorry load of misinformation. The non scientific fringe really does appear to have a huge amount of credibility with the press and especially celebrities who are unfortunate enough to have a child diagnosed with autism.

  6. So did you read every paper I linked to in my discussion of fevers? Did you understand them? Did you read any of them? If you want to understand them I would be happy to explain them to you.

    When you read enough to be able to discuss the topic intelligently get back to me. Since the recent press reports concern mitochondria, a place to start is on how nitric oxide is what triggers mitochondria biogenesis. Not enough nitric oxide, not enough mitochondria. Simple enough for you?

    Dismissal of ideas due to ignorance is not skepticism.

  7. Thank you,

    I just knew the skeptics guide would come to the rescue. I'm looking forward to next week, as always.



    You're "real" picture (Avatar?) is way cuter than your cartoon one. Not many people could say that!
    It's damn hard to compete with cartoons for "cute" but you DO pull if off. (Of course the cartoon is cute too…)

    As usual, I'm just sayin…

  8. daedalus2u:

    The primary problem with the paper you cite seems to be the issue quoted above: the only evidence suggesting a connection between fevers and ASD seems to be unreliable. Here's the relevant part:

    The data collectors were the children's parent or guardian, the people who know them best. They would be the most accurate assessors of the child's behavior, provided that confounding factors did not introduce bias. The anecdotal comments of people in blogs expressing skepticism would suggest that any bias would be to expect worse behavior during a fever.

    I don't think this justification about expected bias is enough to suggest a real connection. I want to see a study where both the fever and the symptoms of autism were being directly measured by scientists.

    Also, I' m really credulous of the claim that parents would be the most accurate assessors of a child's behavior. There are many reasons to suspect observational bias on their part.

  9. Er, didn't mean to say "credulous" above, in that last paragraph. Let me try that again;

    There's no particular reason to think that parents would be "the most accurate assessors of the child's behavior". Even without the "confounding factors" of prevalent ideas about vaccines, it doesn't seem reasonable to expect that parents will be objective observers of their own children.

  10. I love that we have a moving goalpost right here in the comments.
    “Of course thimerosal doesn’t cause autism! That’s just silly pseudoscience. What REALLY causes autism is nitric oxide deficiency!”
    Nitric oxide is also “connected” to diabetes, colitis, Crohn’s disease, and many other with different pathophysiologies.
    It’s highly unlikely that a single disorder would cause so many different problems with completely different mechanisms.
    Additionally, his premise is based on the conclusion that fevers reduce the symptoms of autism. The only study that points to this conclusion relied on a questionnaire filled out by the parents regarding any change in their child’s behavior, which is highly subjective to say the least.

  11. carbon, I gather you are not a parent. Parents absolutely are the most accurate assessors of their child’s behavior. You need someone who is very familiar with the child to be able to assess changes in the child’s behavior positive or negative. There is a lot of stress associated with social interactions with non-familiar individuals. That stress (if it is severe enough) causes an exacerbation of autism symptoms, what is called a “melt-down”.

    My wife and I are the parents of two autistic teenage boys. We have spent more than 15 years trying to correlate changes in their behavior with possible *causes*. They are less likely to tantrum, etc, when they are sick in general (colds, fever), but they are also less likely to display autism *symptoms* while in the toilet or asleep.

    Look, here's the clue- When your grand idea takes this form:

    <code>"If you are interested in the [noun]_______[/noun] connection to [name of disease]_______ [/name of disease](what I think is the “real” cause), the only place you are going to find it is on my blog (so far)."</code>

    You might be a crank.

  12. Of all the bits of my brain which are gradually making the conversion to skepticism, this one is probably the farthest along. I am the mother of an autistic 5-year-old, and I have heard just about every theory out there about potential causes and therapies.

    The key word here is THEORY. Nobody knows. Nobody knows what causes it, and while some therapies work wonders with some autistic children, other kids respond totally differently and need a different approach. Some of the reasons for that are known, some are not. There are even theories that the whole category of disability known as autism is actually two and possibly three separate disabilities that present similarly. Nobody knows.

    For my son, language therapy has worked wonders. Nightly qi-gong massage, while I believe absolutely ZERO of its claims to open up his chi, was a wonderful way to help him get over his hypersensitivity to touch. A regular routine, intentional conversational techniques to help him get out of his verbal loops, careful introduction of new foods into his diet, these are just a few of the things we've tried that worked. Practical is good. Bashing my head against the wall about hypotheticals that are out of my control — not so good.

    Yes, I think it would be great if reliable, large-scale research came up with some avoidable causes. Yes, I hope that more therapies are found that are proven to be as effective as the ones we've used. But until that time, I simply have to let a lot of the "news" roll off me.

    In particular, I refuse to feel guilty for vaccinating my son. Three reasons:

    1. He refused to be held when he was only days old, and I don't think he'd had ANY vaccinations yet by then.

    2. Autism is bad, but dying of preventable disease is worse.

    3. There's not a damn thing I can do about it now, and as a recovering Baptist, I've got enough guilt already, thank you very much. :|

  13. There are many published anecdotes of resolution of autism symptoms with fevers going back decades. This was the first prospective study of the effect. It was by senior researchers in a peer review journal of the highest caliber. This is not at all like the schlock crap the anti-vaccine people put out.

    There is gigantic evidence for resolution of behavioral symptoms produced by disorders characterized by neuroinflammation (which autism is) by fever therapy.

    Fever therapy (induction of periodic fevers for a month or more by giving patients malaria) WAS THE STANDARD OF CARE FOR NEUROSYPHYLIS FOR DECADES! If you were diagnosed with neurosyphilis 80 years ago it would have been malpractice to not treat it by giving you malaria.

    Neurosyphilis was a death sentence. Virtually 100% fatal in a couple of years. Fever therapy cured many thousands. Neurosyphilis is characterized by neuroinflammation and the symptoms are improved dramatically (but temporarily) via injection of bacterial lipopolysaccharide.

    carbon, I gather you are not a parent. Parents absolutely are the most accurate assessors of their child’s behavior. You need someone who is very familiar with the child to be able to assess changes in the child’s behavior positive or negative. There is a lot of stress associated with social interactions with non-familiar individuals. That stress (if it is severe enough) causes an exacerbation of autism symptoms, what is called a “melt-down”. Using clinicians unfamiliar to the child would induce greater bias and error than using the child’s parent. Many of the published anecdotes were by clinicians working with institutionalized children reporting on changes when epidemics would hit the ward and all the children would get sick nearly simultaneously. Those clinicians did know the children well, so their reports were reliable (though anecdotal). Stress incidentally causes NO levels to go down.

  14. Interestingly, in my experience, parents are the LEAST accurate assessors of their children’s behaviors. High personal stake colors perceptions more than anything. Regardless of what they’re supposed to be looking for, parents almost invariably see something substantially different from reality.

  15. For a skeptic, the most important person to be skeptical of is yourself. The essence of skepticism is to be skeptical of "arguments" that are not based in facts and logic such as the example you just used.

    "If you are interested in the [noun]_______[/noun] connection to [name of disease]_______ [/name of disease](what I think is the “real” cause), the only place you are going to find it is on my blog (so far).” You might be a crank.

    If your "argument" can fit into a formula with no facts or logic, it isn't a skeptical argument. It isn't an "argument" that any true skeptic would use. If someone uses such an argument, they are not being a true skeptic. I do appreciate that I was being provocative, and that those who took the bait were being sandbagged (a little bit). But how else to separate the true skeptics from those who are here to try and impress and pick up the skepchicks?

    NO levels do go up during sleep. Inhibiting nitric oxide synthase inhibits sleep. Poor sleep is a common characteristic of ASD individuals. The toileting anecdote is interesting. The anal sphincter is nitrergic, it is relaxed by neurogenic production of nitric oxide. Oral nitroglycerine does produce a prompt relaxation of the anal sphincter. Constipation is a common symptom of ASDs.

    If people want to discuss the details of my low NO hypothesis of ASDs, the appropriate place to do that is over on my blog. I don't want to hijack this thread. The recent fever paper is only a small part of the evidence the hypothesis is based on. You have to go back into my archives to see that. There is a lot of stuff I haven't put up there yet. As far as I have been able to determine, there is nothing in the scientific literature incompatible with the low NO hypothesis of ASDs. If there is any data in the literature that is incompatible I would be very interested in knowing what that is.

  16. daedalus2u, I've got to say that I am quite skeptical that a major medical discovery would first be announced on a blog. What is your expertise? Are you a doctor or a medical researcher? Why didn't you write a paper for a peer-review journal if you have such a substantial discovery to announce? Just curious….

  17. I know this is going to activate everyone's "crank detectors", but the editors and reviewers of peer review journals are only human, and they have extreme difficulty working outside the scientific paradigms they are accustomed to working in. Thomas Kuhn discusses this at length in his book "the structure of scientific revolutions".

    For example, there were some senior scientists who simply couldn't accept relativity, or even the photoelectric effect. Robert Millikan couldn't accept that the photoelectric effect was "real", even a decade after the data that he generated had convinced virtually everyone else it was correct.

    I have submitted things to journals and have been told it is "not interesting" (with no other feedback). I have presented posters at conferences, but to understand the low NO hypothesis of ASDs, you need to understand both ASDs and nitric oxide physiology. Without sufficient background in both it can't be evaluated. So far, people have not been willing to understand the background sufficiently to see where NO fits in the characteristic physiology of people on the autism spectrum. They just glaze over.

    It is very much a "chicken and egg" problem, a "catch -22". It is out of the "mainstream" so it is considered "extraordinary", extraordinary claims require extraordinary data which requires funding which requires data which requires funding. It doesn't matter that I don't consider it extraordinary. I think it is quite ordinary. It fits the data in the literature better than any other explanation does. To me, that makes it quite ordinary. But it isn't what other people are working on, it isn't genes, it isn't mercury, it isn't vaccines, it isn't toxins. It is something that no one working in the autism field has thought of before. Even though everyone working in the autism field knows that the details of what they are working on don't explain everything. There are identical twins that are discordant for autism. There are people with autism who have never been vaccinated, who have no exposure to mercury, no exposure to toxins.

    The "conventional wisdom" about ASDs is that they are "disorders", and that the characteristic ASD behaviors are all pathological. This may be true in some cases, in many cases it is not. In many cases an ability that is actually superior is called "pathological". A very useful video which demonstrates this is here

    Also look at the wiki page on it. How can such a common set of behaviors be due to some idiosyncratic pathology? Many of the behaviors are not detrimental, other than because NTs think they are detrimental. It is like many other human characteristics. The major (if not the only) adverse effect is the discrimination such characteristics elicit from the larger community. Essentially the only bad thing about being black, female, an atheist, Jewish, etc. is how the larger community treats you.

    I think that many of the characteristic behaviors are "features", that were adaptive during early human evolutionary history. These include disrupted communication, social isolation and repetitive behaviors. In many innovations, the most important factor is ignoring the "conventional wisdom" that it can't be done or that the idea is wrong. Robert Millikan couldn't accept the photoelectric effect because he "knew" that light was a wave. Einstein's photoelectric equations had to be "wrong" because they didn't describe wave-like behaviors. Even though they did describe all the observed behaviors of light as precisely as Millikan could measure them. Millikan could never have originated the photoelectric effect hypothesis.

    The use of manufactured stone tools originated about 2.7 million years ago. I have no doubt that 2.8 million years ago, the "conventional wisdom" was that stones were useless as tools. When the first individuals made and used stone tools, they did so while other individuals were telling them they were wrong. Making stone tools requires considerable manual dexterity and skill. Manual dexterity and skill that can only be achieved by repetitive practice. Repetitive practice that non-understanding individuals would think was useless and pathologic. Even now, what does it take to understand quantum physics? 8 years of grade school, 4 years of high school, 4 years of college, 5 years of graduate school. How many people don't understand the value of spending 20 years being educated? Every one of those people does not understand quantum physics, or anything else that requires 20+ years of education to understand. To them, a desire to spend 20 years in school is pathologic, it means one is a "nerd", or "geek", someone to be shunned or avoided, or picked on, or bullied.

    I am making some progress in advancing this in the autism research community. The focus on genetics is (I think) a wrong approach, but the big universities and consortia pushing it have a lot of influence. The path from genes to behaviors is so complex that we are a very long way from understanding it. I don't think the gene researchers actually understand enough about physiology to appreciate how complicated it is. Also, the non-genetic approaches have been so poisoned by the real quacks that it is hard for non-quackery to be looked at objectively and realistically. The placebo effect works quite strongly on autism (because the placebo effect works by increasing NO levels). There are a few genetic causes of autism that have been identified, I think those are the idiosyncratic exceptions. Any genetic mutation that causes metabolic "stress" is going to lower NO levels and (I think) will invoke the ASD phenotype (more or less).

  18. Daedalus2u: I don't know if your proposed mechanism is right or wrong.

    I do know that you SOUND like a medical crank. "My theory explains all these unrelated things!" is the classical crank belief. Comparing yourself to past heroes of science in your pathfinding is another.

  19. Well, I have to say that this whole topic is interesting and elicits more than a few questions. First and foremost is: why NOT loot at Nitric Oxide? Being a skeptic doesn't mean that everything is wrong. I have heard of a patent clerk that was skeptical about some mathematical theories that were "correct" at the time, until he came up with some new stuff that really threw a wrench in the works. Second, why not continue to study the vaccine/autism link? Just because we haven't found the source doesn't mean that it ISN'T vaccinations. These are some incredibly c0mplex processes here, from the manufacture to the way your body uses them. So, as a skeptic, isn't it reasonable to admit that we don't know EVERYTHING about the connection? Continuing to explore every option is the way to go, not dismiss ideas because they don't appear, initially, to fit. The earth was flat, everyone knew that. There was no question. Then someone said it was round. Wow, that guy must have been nuts. Eventually we were able to learn the mechanisms for proving and exploring it, not just discovering it, so now we all know the earth is a sphere (roughly, for any nitpickers). Isn't it possible that the right correlation just hasn't been made yet? The way I see it is this – no one currently knows what causes autism. So, until a causation can be established, keep looking. Leave no stone unturned. You think NO has a link to autism? Great, run with it. If you can prove it correct you will probably win a Nobel prize for it. Until then, keep looking! Being skeptical is defined by Merriam-Webster online as "an attitude of doubt or a disposition to incredulity either in general or toward a particular object." That leaves room for finding the truth. Maybe daedelus is a medical crank, who knows? Does that mean he didn't find something? Certainly not, nor does it mean that he DID find something. It does no one any good to dismiss things out of hand "just because." Be skeptical, not close minded.

  20. Nipticking, all the things it does explain are not unrelated. They are all related though nitric oxide physiology. It is not my idea that they all involve nitric oxide physiology, I got that from the literature, from the work of others. All I have done is find what sets the basal level and appreciate that because NO diffuses everywhere that all NO pathways are coupled to each other, and also to the basal NO level.

    Once your realize that, and that the basal NO level is a global control parameter, and appreciate how physiology is changed by an increase or a decrease in basal NO, everything sort of falls out (with the details left to the reader, but there are a lot of details).

    I do know that I sound like a crank. Some of that is pulling everyone's chain a little, or rather the chains of everyone who is ready to label non-standard ideas as "wrong" without understanding what those ideas are and how they are backed up (or not) by facts and logic.

    I wasn't meaning to compare myself to Einstein, rather I meant to compare the pseudo-skeptics to Millikan. When an idea is not understood, it is not because the idea is "counter-intuitive", it is because the intuition of those unable to understand the idea is faulty. If we are unable to understand reality as it is, it is we who must change.

  21. Did anyone happen to be watching CNN this morning? The print variety of the reports makes note that thimerosal was removed from vaccines in 1999, something that the tv coverage failed to do. Now, given that a great many people don't bother reading and just take the news that read to them on air at face value, any guesses on how many people are going to keep squawking about mercury poisoning (not to mention, it's probably going to start a new fad, got autism=mitochondrial genetic disorder) despite the recently released studies that show no link between thimerosal and autism?

  22. If most cases of autism (or even a large fraction) actually were a mitochondrial disorder, that would be completely obvious from the genetic work that has already been done. It could not have been missed.

  23. There has been a little bit more out on this specific case. It turns out the affected girl has a specific mitochondrial DNA polymorphism, a substitution which while not common, doesn't seem to be pathological. Her mother has it too.

    The mitochondrial dysfunction diagnosis was based on the presence of the polymorphism (perhaps before it was realized it doesn't seem to be pathological) but also symptoms of not enough mitochondria including elevated lactate, reduced mitochondrial complex activity in muscle biopsy, characteristic muscle pathology.

    These symptoms are all consistent with simple mitochondria depletion, a mitochondrial defect is not necessary at all. In other words, this girl may not even have a "real" mitochondrial defect, just a normal variation.

  24. Do you or anyone you know have any personal experience with this topic? Experience such as working with children who have not been vaccinated, or personally having the fear yourself?
    PLEASE let me know!! I am doing my thesis paper on this issue, and how vaccines do not cause autism. I need some anecdotal considerations.
    Thanks for any help!!

    email me:
    [email protected]

Leave a Reply