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Following an overhaul at ACIP, the HHS secretary took the advice of the committee’s new members, saying he was acting on guidance that dated back to 1999.
Mercury. Element 80 of the periodic table of chemical elements. | Image Credit: © N. Elkha - stock.adobe.com
United States Health and Human Services Secretary Robert F. Kennedy Jr.’s authorization of the Advisory Committee on Immunization Practices (ACIP) recommendation to remove thimerosal, a mercury-based preservative, from all influenza vaccines distributed in the US is drawing mixed reactions, including from those who say the anti-vaccine community’s long-held, oft-repeated contention that there is a link between thimerosal and occurrences of autism and other neurodevelopmental disorders in children is false (1,2).
Kennedy’s inking of the recommendations on July 23, 2025, came approximately a month and a half after he dismissed all 17 previously sitting members of ACIP, replacing them with new members Kennedy’s staff had taken under consideration (3).
A release from HHS made clear that it was the new ACIP members who “broke with long-standing inaction” by following through, the department said, on a joint strategy proposed by the US Health Service, the American Academy of Pediatrics (AAP), and vaccine manufacturers as far back as 1999 to remove mercury from childhood vaccines (1).
“After more than two decades of delay, this action fulfills a long-overdue promise to protect our most vulnerable populations from unnecessary mercury exposure,” Kennedy said in the release (1). “Injecting any amount of mercury into children when safe, mercury-free alternatives exist defies common sense and public health responsibility.”
Yet AAP says on its website that despite the continued presence of thimerosal in some influenza vaccines, the preservative has been removed from all routine childhood vaccinations since 2001 (4). The websites of the Centers for Disease Control and Prevention—ACIP’s parent agency—and FDA both affirm that multiple peer-reviewed studies have shown no evidence of harm done by the low doses of thimerosal in vaccines (5,6).
It should be noted that the information on both pages has not been updated since December 2024 and January 2025, respectively, in the closing days of President Joe Biden’s administration. AAP said that the CDC document was removed from that agency’s website prior to ACIP’s June 2025 meeting, but it appears to have since been restored (2,5).
“Misinformation about vaccine ingredients unfortunately sows doubt among parents,” Sean O’Leary, MD, AAP chair of the Committee on Infectious Diseases, says in the AAP fact-check (4). “They’re being constantly bombarded by these false claims. The truth is that vaccines and their ingredients have been tested over and over by scientists who have found them to be safe.”
Children’s Health Defense, the nonprofit organization founded by Kennedy with a mission of eliminating toxic exposure in children, applauded the secretary’s action on X, calling it a “major win” (7).
But Truveta, a collective of 30 health systems that says it has a “shared mission of saving lives with data,” published research in June 2025—just as the ACIP meeting at which the thimerosal removal recommendation was made took place—challenging just how big of a victory it would realistically be to take such an action.
In the 2024–2025 respiratory virus season, 96% of the influenza vaccines administered in the US did not contain thimerosal, Truveta found (8). In addition, according to the data collected, the highest rates of thimerosal-free vaccines were observed in patient populations younger than 18 and older than 65.
In that context, some who attended the June ACIP meeting questioned why any action at all needed to be taken.
“The ACIP makes recommendations based on scientific evidence as much as possible,” H. Cody Meissner, MD, professor of pediatrics at the Dartmouth Geisel School of Medicine and the only committee member who voted against recommending thimerosal-free flu vaccines, said at that time (2). “And there is no scientific evidence that thimerosal has caused a problem.”
Citing CDC statistics, AAP reported that 261 children in the US died of influenza-associated illness during the 2024–2025 season (2). That represents the highest number of reported pediatric deaths in a non-pandemic flu season since the metric began to be tracked in 2004.
1. HHS. HHS Adopts ACIP Recommendation to Remove Thimerosal from All U.S. Influenza Vaccines. Press Release. July 23, 2025.
2. Schering, S. HHS Approves Flu Vaccines Without Thimerosal, Manufacturers Expect No Disruptions. AAP.org, July 23, 2025.
3. Cole, C. Implications of RFK Jr.’s CDC Vaccine Committee Overhaul for the Pharmaceutical Industry. PharmTech.com, June 10, 2025.
4. AAP. Fact Checked: Vaccines Do Not Contain Fetal Cells, Thimerosal. AAP.org, last updated May 14, 2025 (accessed July 24, 2025).
5. CDC Vaccine Safety. Thimerosal and Vaccines. CDC.gov, last updated Dec. 19, 2024 (accessed July 24, 2025).
6. FDA. Thimerosal and Vaccines. FDA.gov, last updated Jan. 15, 2025 (accessed July 24, 2025).
7. Children’s Health Defense (@ChildrensHD) on X. X.com, July 23, 2025.
8. Truveta Research. Understanding the Potential Impact of the Upcoming ACIP Vote on Thimerosal-Containing Influenza Vaccines. Truveta.com, June 26, 2025.
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