In a significant shift in U.S. vaccine policy, Health Secretary Robert F. Kennedy Jr. has approved the discontinuation of influenza vaccines containing thimerosal — a mercury-based preservative — from nationwide distribution.
The decision follows a recommendation by a vaccine advisory panel composed of members selected by Kennedy. The panel endorsed the exclusive use of thimerosal-free flu shots, despite longstanding scientific consensus affirming the preservative’s safety.
According to data from the previous flu season, approximately 5% of administered influenza vaccines in the United States were multi-dose vials containing thimerosal. These formulations have been gradually phased out over the past two decades, primarily as a precautionary move to limit mercury exposure in young children.
Thimerosal has long been at the center of public controversy, with anti-vaccine groups linking it to autism and other neurological conditions — claims widely debunked by the scientific community. Kennedy, a longtime critic of mercury in medical products, previously authored a 2014 book advocating for the substance’s elimination from all vaccines.
The U.S. Food and Drug Administration (FDA) maintains on its website that “there was no evidence that thimerosal in vaccines was dangerous,” citing the original phase-out as a safety precaution rather than a response to proven harm.
Despite these assurances, the Advisory Committee for Immunization Practices moved forward with its recommendation. One panel member who opposed the vote emphasized that discouraging flu vaccinations due to the presence of thimerosal posed greater health risks than the preservative itself.
The Department of Health and Human Services (HHS) confirmed that Secretary Kennedy formally adopted the panel’s guidance. Notably, the decision was made in the absence of the Centers for Disease Control and Prevention (CDC) Director, whose approval typically finalizes such policy shifts. President Donald Trump’s nominee for CDC Director, Susan Monarez, is currently awaiting Senate confirmation.
Major vaccine producers, including Sanofi and CSL, are expected to adapt without disrupting supply. Sanofi has acknowledged the policy change and confirmed it will provide sufficient thimerosal-free flu vaccines for the upcoming season. CSL has not yet issued a public response.
The HHS noted that other recommendations from the June meeting of the vaccine advisory panel remain under review.
