As the hypotheses shift…
It’s now been about ten years since vaccines were first blamed to be the cause of autism. First, it was the MMR vaccine. The mechanism by which this vaccine was supposed to cause autism was ill conceived. Measles vaccine virus was proposed to replicate in the intestine causing chronic inflammation and loss of intestinal barrier function allowing for entrance into the bloodstream of encephalopathic proteins causing autism. However, there was no evidence that attenuated measles virus damaged the intestine and no evidence that specific encephalopathic proteins caused autism. Despite the absurdity of the hypothesis, tens of millions of dollars were spent performing many epidemiological studies showing that it was wrong. More recently, in a study by Mady Hornig, the premise on which the hypothesis was based–namely that measles vaccine virus replicated in the intestines in children who later developed autism–was also shown to be wrong.
Then we moved seamlessly to hypothesis number two–that the ethylmercury containing preservative thimerosal caused autism. This, too, was based on a nonsensical notion. Given that the signs and symptoms of mercury poisoning were quite distinct from those of autism, and given that the quantity of mercury contained and likely to accumulate from vaccines was less than a child would encounter in the environment, the hypothesis was ill founded. Still, in response to growing parental concerns, six epidemiological studies were performed showing that thimerosal-containing vaccines did not cause autism. Again, tens of millions of dollars were spent to address a hypothesis that had no rational basis.
But the anti-vaccine forces press on. Now we’ve moved to something that anti-vaccine advocacy groups have been saying for years–it’s just too many vaccines given too early. Let’s compare children who have received vaccines with those who haven’t, they argue. Again, the premise is not grounded in rational pathogenesis. To assume that too many vaccines are the problem, one would have to assume that there is evidence that autism is immune mediated. No such credible evidence exists. Also, as has been pointed out by several of you who have commented on this blog, such a study would be unethical. That vaccine-preventable diseases occur and that vaccines prevent them is not a matter of debate–one cannot follow unvaccinated children prospectively in good conscience. So, the study could only be done retrospectively and would be fraught with bias, primarily differences in healthcare-seeking behavior. And even if performed and performed well, it would not end the debate. Because those who believe that vaccines are causing chronic diseases will never be swayed by data.
It seems to me that if autism advocacy groups gave a damn about children with autism they would demand that we give up the vaccines-cause-autism hypothesis and focus on the wealth of studies pointing to neuronal and developmental proteins expressed in utero or early in development. These studies provide the only reasonable road out of the darkness and into the light.