The newly appointed members of the CDC’s influential vaccine committee meet Wednesday and Thursday under an unusually rapid timeline, with unexpected topics on the agenda.
The seven new members of the CDC’s Advisory Committee on Immunization Practices—one of Health Secretary Robert F. Kennedy Jr.’s recently appointed eight members has already resigned—convene Wednesday for their first meeting, just two weeks after being named to the committee.
The circumstances of this meeting have been unusual from the start. Normally, ACIP meetings take months of preparation and involve a variety of subcommittee meetings with CDC scientists, outside experts and the committee members, with agendas posted weeks ahead of time. A draft agenda for this meeting was posted just last week, with another draft agenda shared Monday and then a final agenda shared Tuesday.
On the docket are a few expected topics along with some unexpected discussion points. The committee is set to hear updates on the safety and effectiveness of COVID-19, respiratory syncytial virus (RSV), anthrax, chikungunya, influenza and measles-mumps-rubella (MMR) vaccines. Most of the presentations will be given by career CDC scientists, including Sarah Meyer, director of the agency’s Immunization Safety Office, and Adam MacNeil, a supervising epidemiologist at the CDC.
More unusual is two presentations on the preservative thimerosal, one on its use in vaccines in general and one specifically on the influenza vaccine. Monday’s draft agenda did not list presenters for these discussions, but Tuesday’s updated agenda confirmed reporting that Lyn Redwood, a registered nurse and former leader of the Children’s Health Defense, a well-known anti-vaccine group founded by Kennedy, will be presenting about thimerosal in vaccines. The committee’s new chair, Martin Kulldorff, will present on its use in influenza instead of just listening, in another break from ACIP norms.
Thimerosal is an anti-fungal and anti-microbial compound that had been used safely in vaccines since the 1930s. Importantly, the use of thimerosal allowed vaccine manufacturers to produce multi-dose vials of vaccines, where a single vial could be used to vaccinate multiple people with fresh needles. Because thimerosal contains a mercury atom, it became a target of anti-vaccine advocates who claimed it had connections to autism and developmental disorders. Redwood’s presentation states that thimerosal is a “known neurotoxin” and advocates for its removal from influenza vaccines for children and pregnant women.
In the late 1990s, the CDC investigated the compound and found no connection to autism and or developmental disorders. Nevertheless, in 1999 the agency asked manufacturers to remove it from most vaccines anyway. According to the CDC, this “was taken as a precautionary step, not due to evidence of harm.”
“We took care of this 20 years ago,” pediatrician and vaccine expert Kathryn Edwards told The Atlantic on Wednesday.
A briefing document shared by the CDC notes that 94% of influenza vaccines used in the U.S. in the 2024–2025 season did not contain thimerosal.
Redwood’s presentation has already attracted attention for a different reason: it appears to cite a non-existent study on “thimerosal exposure.” The use of non-existent sources plagued HHS’ Make America Healthy Again report in late May.
The ACIP meeting today will only have seven members thanks to the withdrawal of Michael Ross, an obstetrician and gynecologist at George Washington University and Virginia Commonwealth University who was selected by Kennedy days after “retiring” all previous 17 remaining members.
“Dr. Michael Ross decided to withdraw from ACIP during the financial holdings review required of members before they can start work on the committee,” an HHS spokesperson said in a statement, according to Reuters.
Kennedy had named financial conflicts of interest (COIs) as a primary reason for the outser of the previous committee members, though experts told BioSpace this was largely ‘a red herring,’ given CDC had long handled COIs cautiously. As for the new ACIP members, industry watchers have raised concerns about the fact that two, Martin Kulldorff and Robert Malone, have both appeared as paid expert witnesses in suits against Merck over alleged harms caused by its HPV and mumps vaccines. Experts also raised concerns about “intellectual conflicts of interest” relating to their expressed anti-vaccine views.
The new committee will complete four votes across the meeting’s two days. One is for RSV vaccines in pediatric settings, while another is for RSV vaccines provided through the CDC’s Vaccines for Children program, which are administered according to ACIP recommendations. Another vote is on influenza vaccines for the upcoming season, while the final vote is a recommendation on the use of thimerosal in influenza vaccines.
Stay tuned to BioSpace for live updates throughout the meeting.
