In a post that has garnered significant attention on X (formerly Twitter), user @MJTruthUltra alleged a major conspiracy involving the Centers for Disease Control and Prevention (CDC) and vaccine manufacturers. The thread, posted on January 14, 2026, claims that a secret 2000 meeting known as the Simpsonwood conference was held to cover up evidence linking thimerosal—a mercury-based preservative formerly used in some vaccines—to autism and other neurological disorders. The post specifically points to the hepatitis B vaccine as a culprit, asserting that CDC data showed an 11.35 times higher risk of autism in vaccinated children compared to unvaccinated ones, drawing a comparison to the lung cancer risk from smoking.
The post includes a 4-minute video clip featuring Robert F. Kennedy Jr., now U.S. Secretary of Health and Human Services, recounting the events during an interview. In the video, Kennedy describes a preliminary CDC study from 1999 analyzing over 100,000 children's records, which he says revealed alarming associations between thimerosal exposure in the first month of life and conditions like autism, speech delays, attention-deficit disorder, and hyperactivity. He alleges that instead of alerting the public, officials convened at the isolated Simpsonwood Methodist retreat in Norcross, Georgia, to discuss burying the data due to concerns over the vaccine industry's profits. Kennedy obtained transcripts of the meeting in 2005 via the Freedom of Information Act and calls the contents "horrific," quoting participants as admitting, "We are causing autism."
As of 10:26 AM CST on January 14, 2026, the post has amassed over 21,000 likes, 10,000 reposts, 453 quotes, 482 replies, and more than 1 million views, indicating strong resonance within certain online communities.
The Simpsonwood meeting was a real event: a two-day scientific review in June 2000 convened by the CDC to discuss preliminary findings from the Vaccine Safety Datalink, a database tracking health outcomes in vaccinated populations. The focus was on epidemiologist Thomas Verstraeten's initial analysis, which suggested potential associations between cumulative thimerosal exposure and certain neurological outcomes, including a relative risk for autism in the highest exposure group.
However, Verstraeten himself emphasized at the meeting that these were early, unadjusted results, and the overall trend for autism was "not significant."
Follow-up studies, including Verstraeten's peer-reviewed 2003 paper in Pediatrics, refined the data with larger cohorts and adjustments for confounders, finding no causal link between thimerosal and autism.
Kennedy's narrative gained traction through his 2005 article "Deadly Immunity," published in Rolling Stone and Salon, which portrayed Simpsonwood as a secretive cabal prioritizing industry profits over public health.
A 2007 U.S. Senate investigation reviewed these allegations and concluded they were "unsubstantiated," finding no evidence of a cover-up or misconduct at Simpsonwood.
Extensive research since then, including reviews by the World Health Organization (WHO), Institute of Medicine, and multiple large-scale studies, has consistently shown no link between thimerosal, vaccines, or the hepatitis B vaccine and autism.
Autism rates have continued to rise even after thimerosal was phased out of most U.S. childhood vaccines by 2001 as a precautionary measure, attributed instead to improved diagnostics and broader criteria.
Conflicts of interest were noted in some investigations, such as those involving committee members with ties to vaccine makers, but these did not alter the scientific consensus.
As of 2026, thimerosal has been absent from U.S. pediatric vaccines recommended for children under 6 since 2001, including the hepatitis B vaccine, except for some multi-dose flu vaccine formulations.
Single-dose presentations are widely available without it. Recent policy shifts under the Trump administration, including Kennedy's influence, have led to changes in vaccine recommendations: the Advisory Committee on Immunization Practices (ACIP) voted in December 2025 to drop universal hepatitis B vaccination at birth, opting instead for shared clinical decision-making with parents.
Kennedy has also pushed globally for thimerosal removal, raising concerns among experts that it could erode vaccine confidence abroad, where the preservative is still used to prevent contamination in multi-dose vials.
This post's resurgence aligns with ongoing debates over vaccine policy in the U.S., amplified by Kennedy's role at HHS. While it taps into distrust of institutions and Big Pharma, critics warn it spreads misinformation that could further decline vaccination rates, already strained by recent outbreaks of preventable diseases. Public health advocates emphasize that vaccines remain one of the safest and most effective tools for protecting children, with rigorous safety monitoring in place.
