Do Vaccines Cause Autism? Science Says No

child after getting a vaccine
Photo by CDC on Pexels

Chances are, you’ve heard the idea that vaccines can cause autism. Various organizations and individuals champion this notion; one of the most prominent is actress Jenny McCarthy, whose son was diagnosed with autism at age 2. She has an autism-related organization called Generation Rescue, and on its website is a guide to vaccine safety. Note: Since the time of writing, the Generation Rescue website has been taken down.

I was a bit surprised by how relatively toned down it was; however, I got more of what I expected on a site it linked to, the National Vaccine Information Center. It includes a “cry for vaccine freedom wall” and a “vaccine victim memorial”. It has a database of reported adverse reactions to vaccines, and a search for autism spectrum disorder yields 391 case reports. One thing that struck me was the seemingly random grab bag of other symptoms/conditions that were being attributed to the vaccine at the same time.

The origins of anti-vax

So where did this idea come from that autism can result from vaccination? In 1998, the prominent medical journal The Lancet published an article by Dr. Andrew Wakefield and 12 other scientists that looked at 12 children who had bowel disorders and autism. It stated:

“Onset of behavioural symptoms was associated, by the parents, with measles, mumps, and rubella vaccination in eight of the 12 children.”

However, in 2004, 10 of the original 12 authors published a retraction in The Lancet of their interpretation of the results of the 1998 study, including the link between MMR vaccine and pervasive developmental disorder. In 2010, The Lancet retracted the published article entirely, stating that parts of it were incorrect or blatantly falsified.

In 2010, the UK General Medical Council concluded that Andrew Wakefield had committed scientific dishonesty and breach of duty, and was “guilty of serious professional misconduct.” For several reasons, including his “wide-ranging transgressions” and “disregard for the clinical interests of vulnerable patients”, his name was erased from the Medical Registry, an extreme action that they justified in part by his lack of insight. Clearly, this is not an individual whose ideas should be considered credible.

A 2007 paper in Current Opinion on Infectious Diseases dismissed papers linking autism and MMR vaccine as methodologically flawed and “not scientifically stringent.” A 2007 article in The New England Journal of Medicine addressed concerns about thimerosal, a vaccine preservative containing small amounts of mercury well within the World Health Organization’s acceptable limits. The article concluded that the baseless association between thimerosal and autism “has given rise to a cottage industry of charlatans offering false hope, partly in the form of mercury-chelating agents.”

A 2014 paper in the journal Vaccine found no relationship between autism and vaccination in general, or specifically MMR vaccine, thimerosal, or mercury. A 2010 article in Clinical Infectious Disease stated that:

Twenty epidemiologic studies have shown that neither thimerosal nor MMR vaccine causes autism. These studies have been performed in several countries by many different investigators who have employed a multitude of epidemiologic and statistical methods. The large size of the studied populations has afforded a level of statistical power sufficient to detect even rare associations. These studies, in concert with the biological implausibility that vaccines overwhelm a child’s immune system, have effectively dismissed the notion that vaccines cause autism.

Facts aren’t enough?

Yet the overwhelming evidence hasn’t been enough to convince the anti-vaxxers.

Part of the problem is that children can start showing signs of autism around the time they’re getting some of their childhood vaccinations. People may mistakenly assume that this temporal correlation means that there’s a cause-and-effect relationship.  That logic is fundamentally flawed, though; anyone with some degree of research literacy knows that correlation and causation aren’t the same thing.

Herd immunity

This matters because, in an unreasonable attempt to avoid autism, parents aren’t vaccinating their kids. That puts other people at risk. Certain individuals can’t get vaccines for medical reasons, including a compromised immune system, which is where the concept of herd immunity becomes important. Herd immunity refers to the idea that if a high enough percentage of the population is vaccinated, an infectious organism has a hard time moving through the population, which serves to protect those who aren’t vaccinated.

The percentage of the population that must be vaccinated depends on how contagious the infectious agent is; for a highly infectious illness like measles, 90-95% of people must be vaccinated to achieve herd immunity. If the anti-vaxxer movement gains enough steam, this means some of the most vulnerable members of the population may suffer.

Imagine how much good could be done if all the energy and money that goes into anti-vaxxing could be diverted into better understanding autism spectrum disorders and how parents of neurodiverse kids can help them thrive.

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21 thoughts on “Do Vaccines Cause Autism? Science Says No”

  1. I never bought the autism vaccine connection from the start. Glad it was finally debunked. However there are still a lot of parents who are denying their children vital vaccines. Hope they learned sooner than later that they are potentially harming the health of their children.

  2. wanderingrecklessly

    I agree. I have a daughter with a heart defect and vaccines are pretty much mandatory for her. I wish parents would see that children with life threatening issues who can or can’t have these vaccines rely on the others to be part of the solution in prevention. Great post🙂

      1. hipandhumblepaperworks

        Every year students from Principia (sp?) Collage die because they refuse to get the recommended vaccinations? It blows my mind how parents ignore medical professionals. Even when seeing the death toll every year at that collage. Scientists have advanced degrees usually multiple degrees in their field but some parents think they know more than educated medical professionals. It just doesn’t make sense to me. As a hypothetical example if your child had cancer would you refuse treatment because the treatment could have potential side effects? Thank God my mother wasn’t one of those parents because i would not have lived to see my 17th birthday. As a result of metastatic cancer at 16 I was given very aggressive radiation treatments after 2 surgeries. I had one recurrence at 35 with an additional radiation treatment. I am currently 55 and cancer free. Did I experience negative effects of the radiation? Yes I did, however it is an extremely small price to pay to still be alive 39 years after my original cancer diagnosis. Sometimes you have to have faith. My immune systems is compromised as a result of treatment for Rheumatoid Arthritis. Do I want to be around children or people that have not received their vaccinations. Unequivocally NO. I thought think I have strayed off topic. But I do have one more question for the people who do not vaccinate. If you have pets at home, do you take them to the vet for their recommended vaccinations, rabies and all other shots? Do they get heart worm preventative medicine? Do you want your child around a dog or cat who hasn’t had all their recommended shots? Something tells me you would not.
        I apologize for my long rant. It just makes me crazy how parents can think not giving their children vaccines can have a good outcome. In my opinion it isn’t good for them as well as the public!

  3. Yes! Educate! I’m ALMOST to the point where I think parents should get child neglect charges for not vaccinating their children unless there’s a real medical reason. A bit extreme, I know. It just frustrates me how uneducated people are about vaccinates.

  4. I enjoyed this post! I 100% agree with you. I can’t believe people believed in that! Being someone who has worked with autistic children, I understand how frustrating parents MUST feel raising a child with autism. But I feel it’s WRONG to place ALL blame on vaccines. In fact MOST of us have used them and we’re all okay.
    Unfortunately nobody knows WHY and HOW autism occurs, but why not instead of parents blaming vaccines and ironically prevented them from getting the treatments from getting diseases like the mumps and measles, they learn to truly LOVE and ACCEPT their children for who they are???

  5. The thing I hear a lot from people who are against vaccinating their children is that doctors and nurses get very little education about how vaccines work, so how could they know? And this is a problem. Doctors and nurses who have comparatively little background will struggle to answer follow-up questions about the dangers of vaccinations to patients and parents alike. But there’s also a different between taking courses in medical school about vaccinations and knowing how to read scientific literature with a fairly complex understanding of statistics. It’s the researchers and statisticians, not the doctors, that I trust most when it comes to weighing the pros and cons of vaccinations. And I say this as someone who works with family practice doctors everyday–though some of them can also just talk and talk about how vaccines work, regardless of how much they actually learned about it in school.

  6. Most scientific and medical experts are satisfied that no connection exists between vaccines and autism and other neurodevelopmental disorders. Still, critics continue to question the issue. Not only do they question the relationship between MMR and thimerosal and autism, they bring up further culprits they believe might play a role in development of autism.

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