Do Vaccines Cause Autism?
There’s nothing more scary for parents than the thought that they might hurt their children. The controversy about vaccines and autism is frightening, but seems to have little scientific backing.
It started in 1998. The Lancet reported on 12 children with gastrointestional problems that they believed were caused – at least partly – by vaccinations. They claimed those problems contributed to autism and other conditions in the children.
Initial research seemed to support their argument: Unusual levels of measles virus RNA (a type of DNA) was found in certain parts of the kid’s bodies. But on two levels their analysis was refuted: by massive analysis of hundreds of thousands of children and autism, and by carefully examining their scientific method.
Massive amounts of evidence shows that the large increase in autism over the past few decades is not associated with vaccination.
One study in Denmark compared 500,000 children vaccinated against 100,000 who weren’t. They had pretty much the same chance of autism.
The measels, mumps and rubella (MMR) vaccine was started in 1988 in London and no correlation was found between that and an increase of autism. Additionally, the vaccination efforts initially were distributed in clusters: not everyone got it at once. No such cluster effect was found in autism rates.
Similar data show that introduction of MMR in Japan in 1993 was not correlated with increase in autism rates. One thing is consistent: analysis of tens of thousands of kids shows again and again no risk for autism associated with vaccine use.
Refuting the science
How might vaccines cause autism? The most prominent theory was that they somehow trigged an “aberrant immune reaction” that caused damage to the brain. The gastrointestional upset, for instance, might allow toxic proteins to reach the brain that otherwise wouldn’t.
The evidence for this theory was that a few kids with autism had been shown to have measles virus RNA in parts of the body where they shouldn’t be, like inside certain blood cells.
Suspicion of this theory was raised when multiple other studies were unable to replicate the findings.
D’souza et al carefully analyzed the reports and showed that their results were most likely because of mistakes. Either because of false positives or because of mistakes in the lab with how the materials were dealt with.
Another theorized problem was the presence of thimerosal in vaccines. Superficially, it seems insane to include it; it is, after all, mercury, and we all know how dangerous that is.
Thimerosal, however, is a specific type of mercury called ethyl mercury, which is biodegradable and does not cause toxic build up in the body. Similarly large epidemiological studies have shown that it is not associated with autism.
Finally, all vaccines are now available without thimerosal.
There is no denying that diagnoses of autism have really, really increased over the last few decades. But it’s hard to say why. Increased recognition must play a large part, as well as diagnosing milder cases that would have previously been ignored.
It is also possible that other environmental issues play a role.
Vaccines are extremely important to protect children from diseases.
Next Article: Treatments of Autism
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Vaccines and Autism: Evidence Does Not Support a Causal Association
No Evidence of Persisting Measles Virus in Peripheral Blood Mononuclear Cells From Children With Autism Spectrum Disorder
Has the Measles-Mumps-Rubella Vaccine Been Fully Exonerated?