Wednesday, September 26, 2007

Another nail in the coffin for vaccine-autism link

The CDC reported today that a study found little evidence to indicate the vaccine preservative, thimerosal (which contains mercury), caused significant neurological problems in children.

The findings suggest "the higher thimerosal content that vaccines had back in the 1990s did not lead to harmful effects in children in performance on standardized testing at age seven to 10," according to Dr. Anne Schuchat, director of CDC's National Center for Immunization and Respiratory Diseases.

The study did not look specifically at autism (a separate CDC study is focused on that specific condition), but
it used several tests to examine the effects of thimerosal exposure on intelligence, speech, language and motor skills in children between the ages of seven and 10.

Dr. Schuchat again:
"Some of the results suggested that exposure to higher thimerosal quantities led to better performance. And some of the tests showed that exposure to higher thimerosal content led to worse performance. So the totality of the results are quite reassuring and suggest continued to reaffirm the safety of vaccines."

In other words, if thimerosal levels obtained through childhood vaccinations had a significant impact on mental functioning and/or autism, the study should have found a general trend towards worse performance among kids who had exposure to higher levels of the preservative. The study didn't find that, so we can conclude from that thimerosal, at least at the levels kids would receive through vaccination, poses little, if any, risk. Of course, this is no longer a concern because thimerosal has been eliminated from most childhood vaccines.

But those who remained convinced vaccines play a role in causing autism (in spite of any credible scientific evidence supporting this dubious connection) were unswayed and I'm sure their reports attacking the study on various, probably misguided and misinterpreted, grounds will soon be forthcoming.

But as the vaccine-autism believers clamor about unsubstantiated government cover-ups or researchers' ties to pharmaceutical companies, they usually fail to acknowledge the overwhelming, life-saving benefit of vaccines or the many studies refuting any connection between autism and vaccines, which always makes me wonder about their real motivations.

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