The widely disseminated comments of many organizations and authorities would lead one to believe that any possible linkage between vaccination and autism has been entirely disproven. That is not so. The theory that there might be a connection is biologically plausible. One of the most consistent biological abnormalities among children with autism is their limited ability to detoxify heavy metals. It would be a real possibility then that repeated doses of a heavy metal like the mercury preservative, which had been used in nearly all vaccines, would lead to autism in some individuals. However, a theoretical possibility means just a hair more than nothing. A newly published study supports the view that there may well be a connection between vaccinations and autism.
The authors of this study analyzed nationwide data to investigate the connection between total vaccination exposure, autism and speech or language impairment (SLI). Other studies have typically looked for associations between autism and some specific immunization. When the intent of an investigation is to test the theory that some component, present in many vaccines, might be an autism-causing factor, the design of this study, utilizing the sum of vaccination exposure, makes much more sense.
These researchers took into account the potential confusion created by the timing of vaccine and diagnosis of autism or SLI. Autism begins before age 2 but is typically diagnosed years later. If vaccinations were causative, those first two years are when the child would have received them. So, these researchers used total vaccination exposures up to two years of age. Accounting for the delay in diagnosis, they used the rates of autism and SLI at age 8 for their analysis. Because the effect would become evident in individuals 6 years after their exposure, researchers compared rates of vaccinations in 1999 with autism/SLI rates 6 years later (2005). They then analyzed these data, controlling for known and suspected autism risk factors. They also performed statistical tests for potentially confounding health conditions and access to medical care (which might lead to higher rates of diagnosis), finding that these factors did not influence the rates of autism and SLI.
These researchers identified what we call a linear dose-response. For every 1% increase in vaccination rates there was a 1.7% increase in the number of children having either autism or speech/language impairment. This study does not prove that childhood vaccinations cause autism. It does prove that the issue is unresolved and that caution about all vaccinations is warranted.
Thimerosol, the standard mercury preservative formerly used in childhood immunizations, is the preservative in flu shots. As the institutional authorities of conventional medicine push childhood vaccination for flu, despite little research support of effectiveness, these findings suggest that we might be perpetuating a problem. Dropping thimerosol from vaccines was an excellent idea. Why would it be okay to give it to our children in a different shot?