ACIP's June Meeting: Glaring Omissions and Shocking Addition

Medscape

11-07-2025

This transcript has been edited for clarity.
This edition of Medicine Matters addresses glaring omissions and a shocking addition at the CDC's June 2025 Advisory Committee on Immunization Practices (ACIP) meeting.
Department of Health and Human Services (HHS) Secretary Kennedy's newly formed ACIP panel met in June 2025. The meeting was originally scheduled to occur over 3 days but was cut down to a day and a half. A highly anticipated discussion and vote on HPV vaccine did not occur. No vote was taken for COVID vaccines. The shocking addition was the inclusion of an inaccurate and outdated presentation about thimerosal that unscientifically affected the subsequent flu vaccine vote.
ACIP Vote for Clesrovimab
For respiratory syncytial virus (RSV), ACIP did vote 5 to 2 in favor of clesrovimab, a long-acting monoclonal antibody for infants. This product was recently approved by the FDA and received a thumbs-up for inclusion in the Vaccines for Children Program (VFC). We already had nirsevimab, but now with clesrovimab, we have an additional way to protect these little ones.
New COVID Vaccine Formula and Newly Licensed Vaccines
COVID: It's still here, it's not going away, and a lot has been happening in the COVID vaccine space. The FDA announced the new 2025-2026 COVID vaccine formula— a monovalent JN.1 lineage, preferably using the LP 8.1 strain.
Two new COVID vaccine products have been fully licensed by the FDA: a protein-based vaccine, Nuvaxovid by Novavax, and Moderna's new lower-dose mRNA COVID vaccine, mNEXSPIKE. Both vaccines are approved for all adults 65 or older. However, among younger people aged 12-64 years, these vaccines are approved only for those who have at least one health condition that puts them at increased risk for COVID.
Mixed Messages About COVID Vaccination
Leading up to the meeting, there were a lot of mixed messages about COVID vaccination.
May 20, 2025
The FDA Commissioner, Martin Makary, MD, MPH, and the Center for Biologics Evaluation and Research (CBER) Director, Vinayak Prasad, MD, MPH, announced their new evidence-based approach to COVID vaccination during a CBER Town Hall and in a sounding board article published in The New England Journal of Medicine . They discussed requiring additional placebo-controlled trials using saline and said the FDA anticipates it will make favorable risk-benefit findings for vaccination among adults 65 or older and for those 6 months or older with one or more risk factors that put them at high risk for severe COVID outcomes. Both pregnancy and recent pregnancy were on their list of underlying medical conditions that increase a person's risk for severe COVID.
May 27, 2025
One week later, HHS Secretary Kennedy issued his own directive and unilaterally removed COVID vaccines from the immunization schedule for healthy children and for pregnant women. He made this announcement on social media. No new evidence was cited to support this decision. Absent from this announcement was any representative from the CDC or ACIP. This HHS directive triggered color-code changes to the child and adult schedule color tables. COVID vaccines for pregnancy were changed to gray to indicate no guidance/not applicable. COVID vaccines for children aged 6 months through 18 years were changed to blue to indicate shared clinical decision-making.
June 25, 2025
At the June ACIP meeting, the CDC staff gave updates on COVID epidemiology and vaccine safety and effectiveness. Here are some highlights:
Most pediatric hospitalizations (57%) occur in children less than 2 years of age. Most hospitalized children in this age group have no underlying medical conditions.
Rates of COVID-associated hospitalizations are highest among infants less than 6 months of age, followed by those aged 6-23 months. Rates of COVID-associated hospitalizations among infants less than 6 months of age are comparable to rates among adults aged 65-74 years. None of the COVID vaccine products are approved for infants under 6 months of age, so protection can only come from maternal antibodies.
The majority (89%) of children and adolescents hospitalized for COVID had not received a dose of the most recently recommended vaccine.
The vaccine effectiveness update demonstrated that COVID vaccines protect against emergency department and urgent care visits, hospitalization, and critical illness.
ACIP recommendations are supposed to be evidence-based. Another ACIP meeting is planned for August/September. Let's hope for a truly evidence-based vote on the new COVID vaccine formula.
Misleading Presentation About Thimerosal
Now, more about the shocking, inaccurate, and outdated presentation on thimerosal by Lyn Redwood— who was not part of the CDC. Her presentation slides that were originally posted on the ACIP website initially cited a study that didn't exist and did not accurately represent conclusions of other articles that do exist.
A CDC review of the evidence debunked thimerosal myths and refuted Redwood's claims. It clarified that all childhood vaccines licensed and recommended in the US have been thimerosal free since 2001, with the exception of some multidose formulations of flu vaccines. For flu vaccines, 96% are already thimerosal-free. Only 4% of flu vaccines — those that come in multidose vials — contain this preservative. Thimerosal is included to prevent growth of harmful bacteria and fungi introduced by multiple needle sticks into the vial.
The CDC review of evidence also clarified that thimerosal has been extensively studied over decades, with no evidence that it causes autism spectrum disorder or other neurodevelopmental disorders. This is consistent with the FDA's review of thimerosal in vaccines.
The review of the evidence was initially put up on the CDC's ACIP webpage but was then taken down.
Methylmercury vs Ethylmercury
Concerns about mercury are causing confusion. Thimerosal is 50% mercury by weight, but not all mercury is the same. There is methylmercury and there is ethylmercury. Methylmercury — the kind found in long-lived fish — can accumulate in the body and can be toxic and cause harm if consumed in high doses. But that is not what is in thimerosal. Thimerosal is quickly metabolized to ethylmercury, not methylmercury. Ethylmercury does not carry the same risk and is quickly metabolized and excreted by the body.
The panel heard Redwood's inaccurate presentation but there was no opportunity given for a presentation about CDC's updated review and no mention of the FDA's evidence-based assessment.
ACIP Vote on Thimerosal in Influenza Vaccinations
The new panel reaffirmed routine annual flu vaccination for everyone 6 months or older. But when it came to thimerosal, only one ACIP member followed the scientific evidence. The new panel voted to remove thimerosal from flu shots for children, pregnant women, and adults.
This vote could have unintended consequences. Manufacturers may now be forced to turn to other, less-studied preservatives to prevent contamination in multidose vials. This decision will also likely reduce the availability of multidose flu vaccine, which in turn may reduce flu vaccine access in some communities. This vote also increases vaccine hesitancy and concern.
Future ACIP Initiatives From This New Panel?
Comments from the new ACIP chair about future initiatives are very concerning. For starters, he plans to reevaluate the childhood immunization schedule, the birth dose of Hep B, and the use of MMR and varicella vaccines for young children.
If ACIP actually follows this course, it will likely upend the child and adult vaccine schedules and sow further mistrust in vaccines. One thing is clear: Mistrust causes vaccine hesitancy, and hesitancy brings more illness and death from vaccine-preventable diseases.