Citing debunked studies, federal vaccine advisers on Thursday called for only flu vaccines without thimerosal to be used next season, despite pushback from health organizations that said the preservative is safe.
The Centers for Disease Control and Prevention’s (CDC’s) Advisory Committee on Immunization Practices (ACIP) also voted in favor of a new monoclonal antibody to protect infants against respiratory syncytial virus (RSV) during their first RSV season. However, the second day of the committee’s meeting continued to be marked by attempts to lend credibility to misinformation, silence CDC experts and circumvent the usual thorough review of evidence.
“What we've seen these last couple of days, and some of the actions over the last several weeks, is a deliberate effort to distract from the facts and instill fear about vaccines,” said Sean T. O’Leary, M.D., M.P.H., FAAP, chair of the AAP Committee on Infectious Diseases (COID). “The strategy relies on cherry-picked data and junk science to confuse the public and to erode trust in immunizations.”
ACIP members, who were appointed two weeks ago by Health and Human Services Secretary Robert F. Kennedy Jr. after he fired the previous group, at times showed lack of knowledge of clinical trial design, the Vaccines for Children program and the diseases and vaccines being discussed.
AAP liaisons chose not to participate in the two-day meeting that started with Wednesday’s announcement that ACIP would be reviewing the cumulative impact of the child and adolescent immunization schedule.
“This meeting showcased an ACIP that has drifted far from its longstanding focus on science, evidence and public health,” COID member Adam J. Ratner, M.D., M.P.H., FAAP, said. “When that focus returns, so will the AAP.”
Thimerosal in flu vaccines
Thimerosal is a preservative used in multidose flu vaccines but has not been used in other routine childhood vaccines since 2001. It has long been a target of vaccine skeptics who falsely claim it is linked to neurodevelopmental disorders including autism, despite credible studies proving it is safe.
In a highly unusual move, Thursday’s discussion was spearheaded by Lyn Redwood, R.N., M.S.N., who made false claims about the safety and effectiveness of thimerosal and said its removal “is a good place to start with making America healthy again.” She previously led the Children’s Health Defense, an anti-vaccine group founded by Kennedy. The CDC did not make a presentation, which also is highly unusual for ACIP meetings. A document prepared by CDC staff reviewing studies on thimerosal was posted on the CDC website, but it was removed before the two-day meeting started. That document concluded “the evidence does not support an association between thimerosal-containing vaccines and autism spectrum disorder or other neurodevelopmental disorders.” An ACIP member said it was removed at the direction of Kennedy’s office.
“The removal of this document, which contextualized decades of evidence showing no link between thimerosal and neurotoxicity or autism, raises serious concerns about transparency and the integrity of the decision-making process,” Dr. O’Leary said after the meeting. He also criticized Redwood for “the selective use of data and omission of established science.”
Numerous liaisons from health care groups who attended the meeting affirmed the safety of thimerosal and questioned why the CDC’s research had been removed.
Matthew Zahn, M.D., representing the National Association of County and City Health Officials, noted the safety of thimerosal “is based on a 25-year robust history of studies that examined the real-life outcomes for children that have received thimerosal-containing vaccines either in the prenatal or pediatric period.”
“This committee has always prided itself on openness, transparency and review of data and evidence, so I am wondering if we will have an actual scientific presentation with peer-reviewed literature and strong evidence to actually discuss this issue,” said Jason M. Goldman, M.D., MACP, FPCP (Hon.), president of the American College of Physicians.
ACIP member H. Cody Meissner, M.D., professor of pediatrics at the Dartmouth Geisel School of Medicine, was the only committee member who voted against recommending only using flu vaccines without thimerosal.
“The ACIP makes recommendations based on scientific evidence as much as possible,” Dr. Meissner said. “And there is no scientific evidence that thimerosal has caused a problem.”
ACIP members Joseph R. Hibbeln, M.D., Martin Kulldorff, Ph.D., Retsef Levi, Ph.D., Robert W. Malone, M.D., and James Pagano, M.D., voted in favor of recommending only flu vaccines without thimerosal. Vicky Pebsworth, O.P., Ph.D., R.N., abstained.
Recommendations made by ACIP must be approved by the CDC director. In the absence of a director, Kennedy recently approved an ACIP recommendation.
If the thimerosal recommendation is approved, experts said it is not immediately clear how it would impact insurance coverage, availability and the Vaccines for Children program.
Additional flu vaccine recommendations
The committee also voted 6-0 with one abstention in favor of continuing to recommend flu vaccination for everyone 6 months and older without contraindications. Vaccines for the 2025-’26 season will contain a new influenza A(H3N2) component and an option to use FluMist nasal spray at home. In addition, the FDA now allows the recombinant flu vaccine Flublok to be used in children as young as 9 years.
The recommendations come on the heels of a high severity flu season with an estimated 56 million illnesses and 770,000 hospitalizations across all ages, according to the CDC. There were 250 pediatric deaths, the highest on record for a non-pandemic season. About 42% of the children who died did not have an underlying medical condition.
RSV
ACIP members also voted 5-2 in favor of Merck’s clesrovimab (Enflonsia) for use in infants under 8 months born during or entering their first RSV season.
RSV is the leading cause of hospitalization among U.S. infants. Clesrovimab will give providers an option for protecting infants from RSV in addition to nirsevimab (Beyfortus) from Sanofi and AstraZeneca and maternal vaccination with RSVpreF (Abrysvo) from Pfizer. Most infants only need protection from one product.
In April, an ACIP work group said there would be benefits to having multiple products for infants in case RSV develops resistance to one. There also may be more competitive pricing.
Of the two members voting no, Dr. Pebsworth, volunteer director of research at the National Vaccine Information Center, an anti-vaccine group, said she was concerned about use with routine vaccines, although study data presented at the meeting showed it to be safe. Dr. Levi, a professor of operations management at MIT Sloan School of Management, questioned deaths of children in clinical trials, even though they were deemed unrelated to clesrovimab and not out of line with the comparator group. He also questioned the need for the immunization for healthy children.
After the meeting, Dr. O’Leary noted 80% of children hospitalized with RSV have no underlying conditions.
“While the vote to approve clesrovimab may appear to lend this group credibility, today's RSV discussion confirmed that this is an orchestrated effort to sow distrust in immunizations and the vaccine approval process,” Dr. O’Leary said.
“Both clesrovimab and nirsevimab are extremely safe products and also very effective at preventing hospitalization from RSV, which is the leading cause of hospitalization in young children.”
Additional votes delayed
Because the group was behind schedule, it did not discuss measles, mumps, rubella and varicella vaccines as planned following a brief presentation. The agenda also did not include proposals to reduce the number of recommended HPV vaccine doses and reword recommendations on the ages to get vaccinated. In addition, ACIP did not take up Sanofi’s meningococcal conjugate vaccine MenQuadfi, which recently received FDA approval for use in children ages 6 weeks and older.
