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Did CDC Conspire to Hide Vaccine Risk?

'Simpsonwood Conspiracy' Claims Debunked; Concerns Remain

Early Concerns About Mercury continued...

"I was the focal point for this issue in WHO," Clements tells WebMD. "I was as distressed as the CDC to discover that there was such a small body of scientific literature published on the chemical's safety, despite its having been used in vaccines for many years."

To be safe, the CDC, FDA, the American Academy of Pediatrics, and vaccine manufacturers in 1999 agreed to remove thimerosal from all vaccines as soon as possible. This was accomplished in 2001 (except for flu vaccine, now available in thimerosal-free formulations).

But what about children already exposed -- and what about ongoing exposure while thimerosal was being removed?

Thomas Verstraeten, MD, a Dutch researcher working at the CDC, designed and led a study that looked at data from two large California HMOs. He looked for a link between neurological and developmental disorders and thimerosal exposure in 124,170 infants.

And he did indeed see a red flag. Thimerosal appeared to increase children's risk of tics, neurodevelopmental delay, attention deficit hyperactivity disorder, and language delay -- not autism, but close enough for serious concern.

The data would be presented at the July 2000 meeting of the ACIP, a panel of experts that advises the CDC and FDA on vaccine policy. To prepare the vaccination community for the news -- and to figure out how to communicate Verstraeten's preliminary findings to the public -- the CDC held a June meeting to seek the advice of outside experts: 11 "consultants" and 49 "resource specialists."

Because of other meetings being held in Atlanta at the time, the CDC had to look outside the city for a venue. A suburban conference center was open: Simpsonwood.

The Simpsonwood Conference

Kennedy's version of what happened is that the experts conspired to hide the Verstraeten data. From the meeting transcript, he selected phrases that seemed to prove his point. Then Kennedy said that the CDC bribed the Institute of Medicine to whitewash the issue (the IOM's 2001 report found no convincing evidence linking thimerosal to autism; its 2004 report reached the same conclusion).

A close reading of the publicly available transcript leaves a far different impression than Kennedy's selective excerpts suggest. You can read it here.

In the end, the Simpsonwood consultants voted that the Verstraeten study could neither confirm nor rule out a link between thimerosal and autism, and strongly called for more study.

By the time of the ACIP meeting 13 days later, Verstraeten and colleagues had largely completed a planned second phase of their study. Essentially, the same study was repeated in a different HMO.

This time, there was no warning signal. Taken together, the two studies confirmed the consensus of the Simpsonwood meeting: Because they could not establish a definite cause and effect between thimerosal and autism, further research urgently was needed to confirm or reject the link between the two.

The ACIP then unanimously voted to continue the ongoing transition to thimerosal-free vaccines, but not to explicitly recommend against the use of vaccines containing thimerosal or to postpone vaccinations until thimerosal-free versions became available.

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