MYTH: Vaccination as a Cause of Autism
In 1998, Andrew Wakefield and his colleagues published a paper in the journal Lancet. This paper claimed that the MMR vaccine was the cause of autism in 8 children. The mechanism proposed by the authors was the following: vaccine causes intestinal inflammation that leads to the appearance of harmful proteins into the brain through the bloodstream, and as a result, symptoms of autism appear.
The authors interviewed parents of these children and as it was said in the text, all parents confirmed that all of these children had gastrointestinal problems and symptoms of autism appeared a month after receiving the MMR vaccine.
However, later the study was retracted from the journal due to scientific misconduct and misinterpretation of the results:
First, the study was funded by lawyers who had been engaged by parents in lawsuits against vaccine-producing companies, and this was not disclosed in the conflict of interest disclosure. Second, there were ethical violations. The authors had conducted invasive investigations on the children without obtaining the necessary ethical clearances. Third, scientific misrepresentation took place, where they reported that their sampling was consecutive when, in fact, it was selective.
When retracting the article, Lancet wrote a statement that "several elements in the paper were incorrect, contrary to the findings of the earlier investigation".
MMR is a vaccine administered at the age when many children are diagnosed or manifest the first symptoms of autism (15-18 months), so it's merely concincidence if symptoms and the administering of the vaccine overlap. Furthermore, there are studies that show that the symtpoms of autism in children can appear as early as the first month of a child's life, which is contradictory to the timeline of Wakefield's "findings".
Another issue regarding timelines is the introduction of the MMR vaccine. Reports of children with autism date back to 1983 (Hans Asperger) and 1943 (Leo Kanner) respectively, where the MMR vaccine was introduced in 1971.
In order to determine whether or not MMR causes autism, studying the incidence of autism in both vaccinated and unvaccinated children would've be crucial, and the authors failed to conduct this study. Other studies that did conduct this research showed that the incidence of autism is the same or higher in unvaccinated children.
The authors also claim that autism is caused by intestinal inflammation, caused by the MMR vaccine. Intestinal symptoms were observed after, not before, the symptoms of autism in all of the eight cases. This means that the claim that the MMR vaccine causes autism via intestinal inflammation is inapplicable.
After all of this, dozens of studies still continue to refute the connection between vaccines and autism.
Intestinal inflammation that was the main argument in the Wakefield's study, and is often observed in children with autism, but it is not the cause, but rather it one of the consequences of chronic congenital infections.
Read more about gastrointestinal tract problems in children with autism here.