The Centers for Disease Control and Prevention's newly reconstituted Advisory Committee on Immunization Practices (ACIP) voted to recommend eliminating thimerosal from all seasonal influenza vaccines, marking a significant departure from established scientific consensus on the mercury-containing preservative's safety.
In a series of 5-1 votes during the committee's first meeting since Health Secretary Robert F. Kennedy Jr. replaced all 17 previous members, ACIP recommended that children 18 years and younger, pregnant women, and all adults receive only single-dose influenza vaccines free of thimerosal. The lone dissenting vote came from Cody Meissner, a professor of pediatrics at Dartmouth's Geisel School of Medicine, while committee member Vicky Pebsworth abstained from all votes.
Thimerosal Debate Takes Center Stage
The committee's focus on thimerosal surprised many observers, given that 94% of influenza vaccines in the United States already do not contain the preservative. Thimerosal was removed from most childhood vaccines 25 years ago following safety concerns that have since been scientifically debunked.
Lyn Redwood, former president of the anti-vaccine group Children's Health Defense, presented arguments for thimerosal removal, claiming the preservative was "never tested and grandfathered into approval by the FDA." However, her presentation conflated ethylmercury—the form found in thimerosal that is quickly processed and excreted by the body—with methylmercury, which is widely recognized as toxic.
Meissner challenged the presentation, calling thimerosal "an old issue" and emphasizing that ethylmercury "is not associated with neurotoxicity." He expressed frustration that ACIP was dedicating time to the topic, stating, "Of all the issues that ACIP needs to focus on, this is not a big issue."
Access Concerns Raised
The committee's most vocal opponent of the thimerosal restrictions warned about potential consequences for vaccine access. "My concern is that by insisting that vaccine doses not contain thimerosal, that might lower vaccine access," Meissner said. "The risk from the flu is so much higher than [from] thimerosal, I would hate for someone not to receive the vaccine because it does contain thimerosal."
Meissner noted that thimerosal is included in most vaccines administered globally, as many countries cannot afford single-dose vials. "Removing thimerosal from all vaccines used in other countries is going to reduce access to these vaccines, it will increase costs, and I think it's important to note that no study has ever indicated any harm from thimerosal," he said.
Joseph Hibbeln supported considering alternative preservatives for multi-dose vials, stating there is "good data that other preservatives can be used" and hoping the committee would "put on the agenda the consideration of multi-use vials rather than single-use vials that have other better preservatives."
RSV Prevention Recommendations
The committee also addressed respiratory syncytial virus prevention, voting 5-2 to recommend that infants under 8 months born during or entering their first RSV season receive clesrovimab if not protected by maternal vaccination. The FDA approved this monoclonal antibody just 16 days before the ACIP meeting.
Adam MacNeil, a CDC epidemiologist, presented compelling effectiveness data for RSV prevention strategies. He reported that 57% of infants born in the past year were protected either through maternal RSV vaccination or Beyfortus treatment. Real-world trial data showed Beyfortus was approximately 80% effective at preventing hospitalization among infants in their first RSV season.
Meissner praised the RSV prevention results as "spectacular" and "an astonishing accomplishment." He emphasized the importance of including RSV prevention in the Vaccines for Children program to ensure equity: "It would not be right, because these are expensive products, that only well-insured children or in families that are well-insured, have access to this product."
Scientific Community Pushback
The meeting drew significant criticism from public health professionals. During public comment sessions, a pediatric nurse practitioner with over 30 years of experience said the scientific and medical communities are "losing faith in the ACIP because of the bogus reasons that were used to dismiss the 17 members."
Caroline Brown, a general pediatrician from North Carolina, expressed particular concern about the thimerosal focus: "The fact that thimerosal is on the agenda for tomorrow's meeting is particularly concerning, given that it was removed from virtually all routine pediatric vaccines in this country over 20 years ago."
Brown connected the committee's actions to broader public health challenges, noting that North Carolina had just registered its first confirmed measles case of the year. "We must acknowledge that measles spread throughout our country is our reality today only because of the fear-mongering and pseudoscience that has overtaken our country," she said.
Committee Composition and Future Plans
The new ACIP is chaired by Martin Kulldorff, who disclosed he was fired from Harvard for refusing COVID-19 vaccination, claiming he had "superior immunity" from previous infection. Other members include Robert Malone, known for spreading COVID-19 vaccine misinformation, and Retsef Levi from MIT.
Kulldorff announced that upcoming ACIP work groups would examine cumulative childhood vaccine schedules and reconsider the hepatitis B vaccine recommendation for newborns. "An argument could be made for delay of vaccine for this infection, which is primarily spread by sexual activity and intravenous drug use," he said, despite evidence that horizontal transmission within families is a major factor in hepatitis B infections.
The American Academy of Pediatrics boycotted the meeting and announced it will publish its own vaccine recommendations parallel to ACIP's, citing concerns about the committee's scientific credibility following the mass dismissal of previous members.
