If you've been on social media for a long time, odds are that you've interacted with a particular form of anti-vaxxer who believes that increased autism diagnoses are caused by vaccines. This claim isn't substantiated, which we will discuss, and is used in such a manner that is actually harmful for people who are autistic. There have been many studies that have looked at this question, but the one I want to discuss today is a 2009 Clinical Infectious Diseases article that looked at 2 different theories, the MMR vaccines and the use of thimerosal.
To provide some background, we need to understand where the idea of vaccines and autism came from. Andrew Wakefield published a paper in 1998 regarding 8 children who showed symptoms of autism shortly after getting an MMR vaccine. He then proposed the idea that "the MMR vaccine caused intestinal inflammation that led to translocation of usually nonpermeable peptides to the bloodstream and, subsequently, to the brain, where they affected development." (1).
Of course, there are a lot of issues with this study. The big one being that there were no control subjects. This alone, in my opinion, should nullify your causal research, as it will inherently mean nothing. Other issues include the fact that MMR vaccines don't cause chronic intestinal inflammation, and that these gastrointestinal symptoms don't typically predate autism. This is practically Freudian levels of making assumptions based in nothing.
This research we're looking at is a meta-data analysis, meaning that it looked at a lot of other published research to determine a consensus. Some of the studies looked at included: A Finish study including 535,544 children over 6 years and found no diagnostic clustering around MMR vaccination, a Danish study over 7 years with 537,303 children and found no difference in risk of autism diagnosis with vaccinated children and non-vaccinated ones, and an Atlanta study with 2,466 children to determine whether early age MMR vaccination posed a risk, which it did not.
Having showed that the MMR vaccine doesn't increase risk, we move on to thimerosal. Thimerosal is a compound which contains ethylmercury and is used in vaccine preparations. In 1999, an official recommendation was released, calling for the removal of mercury from any vaccine given to infants. Outcry then occurred, with theories of mercury causing autism on the rise. As our research points out, the symptoms of mercury poisoning are not the same as autism, meaning that there wasn't much practical sense in the idea that thimerosal was the cause.
Three ecological studies and four cohort studies in particular were looked at regarding autism diagnosis rates when thimerosal was used, and when it wasn't. Unsurprisingly, rates of diagnosis continued to rise even after thimerosal was removed from common vaccines.
While continuously denying science and pushing the idea that vaccines are dangerous is problematic in general, this claim has specific harm for autistic people. This claim isn't often used as just a fun little tidbit, but as a reason to not get kids vaccinated, implying (or straight up saying) that it's better for their child to have increased risk of a deadly disease than to potentially have autism. It should be pretty obvious that this is a horrible insinuation, and people shouldn't be continuing to use pseudoscience to push the idea that kids are better off sick and dead than neurodivergent.
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