US CDC vaccine panel cites nonexistent study in Thimerosal review, sparks controversy

A review on the use of the preservative thimerosal in vaccines slated to be presented on Thursday to the US Centers for Disease Control and Prevention's outside vaccine committee cites a study that does not exist, the scientist listed as the study's author said.

The report, called "Thimerosal as a Vaccine Preservative" published on the CDC website on Tuesday, is to be presented by Lyn Redwood, a former leader of the anti-vaccine group Children's Health Defense.

It makes reference to a study called "Low-level neonatal thimerosal exposure: Long-term consequences in the brain," published in the journal Neurotoxicology in 2008, and co-authored by UC Davis Professor Emeritus Robert Berman.

But according to Berman, "it's not making reference to a study I published or carried out."

Berman said he co-authored a similarly named study in a different journal - Toxicological Sciences - that came to different conclusions than those suggested by Redwood.

"We did not examine the effects of thimerosal in microglia... I do not endorse this misrepresentation of the research," he said.

Reuters is the first to report on the inaccurate citation from Redwood's planned presentation.

Later on Tuesday, the CDC uploaded a new version of Redwood's presentation, removing the slide that cited the Berman study.

The meeting has become increasingly controversial after Health Secretary Robert F. Kennedy Jr. just weeks ago abruptly fired all previous 17 members of the expert panel and named eight new members, half of whom have advocated against vaccines.

The CDC ACIP Slides have been removed from the CDC website. Will they reappear for public review before the meeting?
Or is HHS "radical transparency" = hiding data and presentations from the public and presenting false data to ACIP? https://t.co/Qxkyl6wDjt pic.twitter.com/8Nh7hT4NHH

— Dr. David B (@boulware_dr) June 25, 2025

Kennedy, a long-time anti-vaccine activist, founded the Children's Health Defense.

Both Republican US Senator Bill Cassidy of Louisiana and Democratic US Senator Patty Murray of Washington said the June 25 and 26 meeting should be postponed.

The summary of the presentation suggested that there are enough thimerosal-free flu vaccines and that all pregnant women, infants and children should receive only those shots.

Those aren't CDC slides. They are the slides for the presentation by Lyn Redwood, former president of Children's Health Defense.https://t.co/vRur0G9ERx pic.twitter.com/VEGsfgWm2e

— Helen Branswell 🇨🇦 (@HelenBranswell) June 25, 2025

It was not clear if the new advisory panel would be asked to vote on such a move.

Redwood's presentation was in contrast to a separate report posted by CDC staff on the CDC website on Tuesday that says evidence does not support a link between thimerosal-containing vaccines and autism or other neurodevelopmental disorders.

Kennedy has long pushed a link between vaccines and autism contrary to scientific evidence.

Redwood could not be immediately reached for comment.

An HHS spokesman said the study being referenced was the Toxicological Sciences study Berman said was being misrepresented.

The CDC's briefing material reviewed some studies on neurodevelopmental outcomes and vaccines that contain thimerosal, which has long been used in the US in multi-dose vials of medicines and vaccines to prevent germs from growing in them.

According to the CDC report, 96% of all influenza vaccines in the US were thimerosal free during the 2024-25 flu season.

It also added that the number of pregnant women receiving a thimerosal-containing flu vaccine has decreased over time, with only 0.3% of doses given in 2024 containing thimerosal.

Kennedy wrote a book in 2014 claiming that thimerosal, a mercury-based preservative, causes brain damage.

On Monday, Cassidy, who heads the US Senate Committee on Health, Education, Labor and Pensions, called for the meeting to be delayed, saying it should not take place with a relatively small panel and without a CDC director in place.

Murray, a senior member and former chair of the HELP Committee, has also called for the fired panel members to be reinstated or the meeting be delayed until new members are appropriately vetted.

Earlier, a newly appointed panel of vaccine advisers by US Health Secretary Robert Kennedy Jr. is now down to seven after a member withdrew ahead of the committee's first meeting, a spokesperson for the Department of Health and Human Services (HHS) said on Tuesday.

Earlier in June, Kennedy had named eight members to serve on the US Centers for Disease Control and Prevention's (CDC)Advisory Committee for Immunization Practices (ACIP), including several who have advocated against vaccines, after abruptly firing all 17 members of the independent committee of experts.

"Dr. Michael Ross decided to withdraw from ACIP during the financial holdings review required of members before they can start work on the committee," HHS spokesperson Andrew Nixon said in a statement, adding the committee would have benefited from his service and expertise.

The New York Times first reported the news on Ross' departure.

A list of voting members for the panel on the CDC's website didn't feature Ross' name as of Tuesday night.

The panel, which advises the US CDC on who should get the shots after they are approved by the US Food and Drug Administration (FDA), is due to meet on June 25 and 26.

It will vote on the safety of flu shots and discuss proposed recommendations for use of the combined MMRV vaccine for children under 5 years of age, according to a draft agenda on the Centers for Disease Control and Prevention's website last week.

A review on the use of the preservative thimerosal in vaccines will also be presented by Lyn Redwood on Thursday during the meeting, a former leader of the anti-vaccine group Children's Health Defense.