The 2000 Simpsonwood CDC conference (officially entitled Scientific Review of Vaccine Safety Datalink Information) was a meeting convened in June, 2000, by the Centers for Disease Control, held at the Simpsonwood  Methodist retreat and conference center in Norcross, Atlanta, Georgia.
A key event at the conference was the presentation by Dr. Thomas Verstraeten of a study, based on data obtained from the Vaccine Safety Datalink, examining the possibility of a link between mercury in vaccines and neurological problems in children who had received those vaccines. After Rolling Stone published a story about the conference and study by Robert F. Kennedy, Jr. containing numerous major errors, the conference became notorious among those who believed that proof of danger from vaccines had been revealed at the conference and then hushed up by government and private industry.
The attendees included 50 experts in fields including autism, pediatrics, toxicology, epidemiology and vaccines. In addition to specialists involved in vaccine research, approximately half a dozen public health organisations and pharmaceutical interests were represented, as well as eleven consultants to the CDC, a rapporteur (Dr. Paul Stehr-Green), and a statistician, Dr. Phil Rhodes, who was to provide a half hour summary review of the proceedings at the end of the second day.
In 1997, the Congress of the United States passed a resolution requiring the Food and Drug Administration (FDA) to review mercury in drugs and biologics. The Simpsonwood conference served the purpose of reviewing findings that resulted from that mandate. 52 representatives from the pharmaceutical industry, the CDC and the FDA gathered at the retreat for two days of discussions, with the main topic of discussion revolving around a presentation regarding statistical research, on reported adverse side effects of vaccines derived from the Vaccine Safety Datalink, that had been conducted by Dr. Thomas Verstraeten.
Three vaccines of primary interest were to be discussed, because they are given early in life. These included the hepatitis B vaccine, the DPT vaccine, and the Haemophilus influenza type B vaccine.
The meeting also served as a prelude to high level government vaccine policy-making meetings, held by the Advisory Committee on Immunization Practices (ACIP), which sets vaccine policy within the US for the CDC. The session was also to serve as the initial meeting of the ACIP work group on thimerosal and immunization. Dr. John Modlin, a faculty member at Dartmouth Medical School, was the chair of the ACIP at the time of the CDC's Simpsonwood conference.
On January 12, 2001, members of ACIP's vaccine policymaking committee met to discuss claims that children given mercury in vaccines had a much higher rate of autism, attention deficit hyperactivity disorder and other neurodevelopmental disorders.
Presentations and supporting documents were to be treated as embargoed until June 21, prior to planned publication at ACIP. After the conference, Verstraeten carried out a planned second phase to further analyze and clarify the study's preliminary findings. A revised publication was released in 2003.
In the June 20, 2005 issue of Rolling Stone magazine, in a story titled "Deadly Immunity", Robert F. Kennedy, Jr. gave an account of the conference and of Verstraeten's study in which he alleged that government and private industry had colluded to "thwart the Freedom of Information Act" and "withhold" Verstraeten's findings from the public. However, Kennedy's article contained numerous significant errors of fact. Most notably, Kennedy claimed that Verstraeten's study showed that "[the mercury-compound vaccine preservative] thimerosal appeared to be responsible for the dramatic increase in autism," and that Verstraeten later "reworked his data to bury the link between thimerosal and autism." Though the preliminary findings that Verstraeten presented at the Simpsonwood conference had seemed to indicate a correlation between mercury-containing vaccines and certain neurological problems, autism was not one of those problems; Verstraeten's Simpsonwood presentation began by discussing autism and concluding the connection between mercury-containing vaccines and autism was "not statistically significant."
By the time Verstraeten published the amended study results in 2003, he had gone to work for GlaxoSmithKline. Kennedy contended that the delay in publication gave Verstraeten sufficient time to fix the data around the CDC's alleged objective of obscuring a link between thimerosal and autism. Dr. Verstraeten denied the allegations, and published an account of the matter in the journal Pediatrics. In September 2007, a summary report of the US Senate's committee on health, education, labor and pensions rejected allegations of impropriety.