[An image of one holding a vaccine. Photo credit: Unsplash]

On June 26, 2025, the US Centers for Disease Control and Prevention (CDC)’s outside vaccine committee held a review on the use of the preservative thimerosal in vaccines.

Thimerosal is a mercury-based preservative that has been the subject of scientific scrutiny for years.

The review was prompted by a report presented by Lyn Redwood, a former leader for the anti-vaccine organization Children’s Health Defense.

During her presentation at the meeting, Redwood argued that thimerosal vaccines should be banned due to their varied impacts on individuals.

She emphasized that numerous vaccines are available that do not contain any thimerosal, advocating that people, especially young children and pregnant women, should receive these thimerosal-free vaccines exclusively. 

Redwood claimed that thimerosal may cause various neurological diseases and neurodevelopmental disorders, including autism. 

Her report cited a study allegedly showing potential long-term brain-related consequences from thimerosal exposure. 

The study published in 2008 was attributed to UC Davis professor Robert Berman.

However, the citation led to immediate pushback when Berman himself denied authoring the conclusions referenced in Redwood’s presentation.

Berman acknowledged that he had conducted a study on a similar topic, but stated that it did not reach the same conclusions that Lyn Redwood proposed in her report.

Berman accused Redwood of misinterpreting his research and stated that the inaccurate citation would not be tolerated, as it failed to reflect the actual conclusions of his work.

This incident has brought up controversial arguments surrounding Robert F. Kennedy Jr., the current US health secretary, who recently replaced 17 members of the expert panel and appointed eight new members in their place. 

The decision has faced criticism because approximately half of the newly appointed members have previously expressed anti-vaccine beliefs and have engaged in various forms of vaccine advocacy. 

Kennedy Jr. himself is a strong believer and supporter in the anti-vaccine idea, which brings up more controversy over the sudden replacement of panel members without clear justification. 

Similarly, the Children’s Health Defense organization that Redwood previously led was founded by Kennedy himself, further raising questions about potential conflicts of interest.

In contrast to Redwood’s claims, a separate report prepared by CDC staff found no credible evidence linking vaccines containing thimerosal to neurological diseases or neurodevelopmental disorders.

This position aligns with the scientific consensus maintained by major health organizations.

Kennedy’s advocacy against thimerosal is not new.

In 2014, he wrote a book making similar claims about thimerosal causing brain damage. 

The controversy has generated calls for action from within the medical community.

Murray, a senior former panel member and former chair, has asked for the reinstatement of the fire panel members to ensure more appropriate representation on the committee. 

The dispute has also affected the committee’s operations.

The head of the US Senate committee on health has announced that scheduled meetings for June 25 and 26 would be delayed.

The postponement resulted from concerns that the meeting should not be conducted without a director in place or with such a reduced number of panel members present.