Debate Over Vaccines and Autism Is Effectively Over

This unpublished letter was sent to the Wall Street Journal in reaction to a piece of theirs on vaccines and autism:

To the Editor:
Re: "Controversial Study Reignites Debate Over Autism and Childhood Vaccines"

Tara Parker-Pope's September 7th Wall Street Journal article regarding the unproven link between the vaccine preservative thimerosal and autism included factual errors and left out important points. The result was a mixed message as to whether or not there is just cause for parental concern.

In May, the Institute of Medicine's Immunization Safety Review Committee concluded that the body of available epidemiological evidence favored a rejection of a causal link between thimerosal-containing vaccines and autism. But in June, private researchers announced they had induced "autism-like" symptoms in a particular strain of mice by exposing them to thimerosal. First, while a heritable sensitivity to mercury is worthy of further study, a single study in genetically modified rodents is shaky grounds upon which to reignite this "debate." Second, it was not mentioned that animal studies have been known, in many cases, to lead us astray, particularly without an understanding of species-specific biochemical mechanisms. Just look at the 1977 saccharin scare.

Given the above, Parker-Pope's warning to parents that pediatricians' shelves may still be stocked with unexpired thimerosal-containing vaccines is not only moot but implausible. In 1999, the FDA recommended the removal of thimerosal from pediatric vaccine production. According to the CDC, the last remaining stock of thimerosal-containing vaccines, excluding some new influenza vaccines, expired in early 2003. But this raises another unmentioned curiosity; if thimerosal is responsible for the so-called "autism epidemic," we should expect a drop in diagnoses since the substance's widespread removal. This remains to be seen. Given that thimerosal has been used in vaccines since the 1930s, it is more likely that the "epidemic" is the result of better diagnostic criteria and autism awareness.

The perpetuation of half-truths and hype on the highly scrutinized issue of pediatric vaccine safety is detrimental to public health due to the following fact: the risk of unimmunized children contracting vaccine-preventable diseases far outweighs the likelihood of their developing autism if vaccinated. Even if a genetic susceptibility to mercury is found in humans, not vaccinating children in an effort to protect them from autism would be akin to keeping them indoors to protect them from lightning strikes.

Aubrey Stimola
Research Intern
American Council on Science and Health