The Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) concluded its two-day meeting on June 26, 2025, with a landmark decision to recommend against the use of thimerosal-containing influenza vaccines. The move, passed by a 5-1 vote with one abstention, marks a significant shift in U.S. vaccine policy and has sparked widespread debate among public health experts.
A Controversial Vote
Thimerosal, a mercury-based preservative, has been used in multi-dose vials of vaccines to prevent bacterial contamination. Although it was largely phased out from pediatric vaccines in 2001, it remains in approximately 4% of flu vaccines administered in the United States, primarily in cost-effective multi-dose formulations used in clinics and rural areas.
The ACIP’s decision to recommend only thimerosal-free flu vaccines was influenced by presentations from individuals with longstanding concerns about the preservative’s safety. Notably, Lyn Redwood, a former leader of the anti-vaccine group Children’s Health Defense, addressed the committee, alleging potential health risks associated with thimerosal. However, extensive scientific research has consistently found no credible evidence linking thimerosal to adverse health effects.
Dr. Cody Meissner, the sole dissenting vote, cautioned that the recommendation could limit vaccine availability and increase costs, particularly in underserved regions that rely on multi-dose vials. “The negligible risks associated with thimerosal do not justify the potential barriers to vaccine access this decision may create,” Meissner stated.
Leadership Changes and Policy Shifts
The vote comes in the wake of significant changes to the ACIP’s composition. Earlier this month, Health and Human Services Secretary Robert F. Kennedy Jr., a known vaccine skeptic, dismissed all 17 previous committee members and appointed eight new individuals, several of whom have expressed anti-vaccine sentiments. Among the new appointees are Dr. Martin Kulldorff, co-author of the controversial Great Barrington Declaration, and Dr. Robert Malone, a vocal critic of mRNA COVID-19 vaccines.
These appointments have raised concerns among public health experts about the committee’s commitment to evidence-based decision-making. Critics argue that the new panel’s actions, including the thimerosal vote, reflect a departure from established scientific norms and could undermine public confidence in vaccination programs.
Broader Implications
The ACIP’s recommendations influence national vaccine policy, insurance coverage, and CDC vaccine procurement. The decision to restrict thimerosal-containing flu vaccines may have global repercussions, particularly in low-resource settings where multi-dose vials are essential for mass immunization efforts.
Furthermore, the committee is reportedly considering a review of the nation’s childhood and adolescent immunization schedule. Such a review could lead to significant changes in vaccine timing and combinations, potentially affecting herd immunity and the control of preventable diseases.
The American Academy of Pediatrics has expressed deep concern over these developments, stating that any alterations to the immunization schedule must be grounded in rigorous scientific evidence. The organization has pledged to issue its own evidence-based vaccine recommendations if necessary.
Public Health Community Responds
The ACIP’s recent actions have prompted a strong response from the broader medical and scientific communities. Many experts warn that the committee’s direction could fuel vaccine hesitancy and lead to the resurgence of diseases that have been largely controlled through immunization.
Dr. Anthony Fauci, former director of the National Institute of Allergy and Infectious Diseases, emphasized the importance of maintaining public trust in vaccines. “Decisions about vaccine policy must be based on sound science and transparent processes. Any deviation from this standard risks eroding the progress we’ve made in public health,” Fauci remarked.
As the CDC awaits Senate confirmation of its new director, the agency’s leadership remains in flux. In the interim, Secretary Kennedy’s influence over vaccine policy continues to shape the nation’s approach to immunization, with potentially far-reaching consequences.
