HHS Adopts ACIP Recommendation to Eliminate Thimerosal From Flu Shots

Secretary of US Health and Human Services Robert F. Kennedy Jr signed to adopt the CDC's Advisory Committee on Immunization Practices (ACIP) recommendations to remove mercury-based thimerosal from all influenza vaccines distributed in the United States. Kennedy has also approved all recommendations issued from the April ACIP meeting, but recommendations from June are still under review.¹

“After more than 2 decades of delay, this action fulfills a long-overdue promise to protect our most vulnerable populations from unnecessary mercury exposure,” Kennedy said in a news release.¹ “Injecting any amount of mercury into children when safe, mercury-free alternatives exist defies common sense and public health responsibility. Today, we put safety first.”

In a vote of 5 to 1 in June 2025, ACIP voted to recommend against influenza vaccines containing the preservative thimerosal. Thimerosal has been widely used as a preservative in some biological and drug products, such as for the safe use of multidose vials. The vote recommended that children 18 years and younger, pregnant women, and adults receive only single-dose influenza vaccines that do not contain the preservative.^1,2

“Mercury is the third most toxic element on earth, only behind polonium and plutonium and has no physiological role in the human body,” Lyn Redwood, RN, MSN, FP, said in an ACIP meeting.² “There is also evidence that thimerosal is not an effective preservative at vaccine levels.”

Vaccine manufacturers have confirmed that they have the capacity to replace the multidose vials, which will ensure that the Vaccines for Children (VFC) program and adult vaccine supplies will not be interrupted.¹

Prior to the meeting, a CDC report found that there was no connection between thimerosal in vaccines and autism or other neurodevelopmental conditions, which were of previous concern. In the report, investigators noted that 94% of all influenza vaccines in the US and 98% of the VFC vaccines were thimerosal free in the 2024-2025 season. Only 0.3% of doses administered to pregnant women contained the preservative.

Data from the majority of studies showed that the vaccine did not increase the likelihood of an autism diagnosis. This was also true for other vaccines, such as the tetanus-pertussis, diphtheria-tetanus, hepatitis, and measles, mumps, and rubella vaccinations.³

However, the report did add that there were findings from non-CDC studies that indicated an association between the preservative and neurodevelopmental disorder, although those studies lacked methodological limitations. One concern was the criteria to diagnose autism changes, and another included reliance on aggregated data for the analysis.³

ACIP recommendations are often considered guidelines by providers and insurance companies to determine the vaccine schedule and what is covered under insurance and the VFC program.

“As a provider, we utilize the ACIP guidelines [regarding] what we recommend for patients for preventive care to prevent diseases and things like that, [and] what's the best thing,” Kevin Cleveland, PharmD, professor at Idaho State University L.S. Skaggs College of Pharmacy, said.⁴ “We refer to those as kind of the standard of care, and going and applying those, and so we're not the only ones, but also insurance companies use that as a guidance for whether a vaccine is going to be covered by insurance.”

READ MORE: Immunization Resource Center

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REFERENCES

1. HHS adopts ACIP recommendation to remove thimerosal from all U.S. influenza vaccines. US Department of Health and Human Services. July 23, 2025. Accessed July 24, 2025. https://www.hhs.gov/press-room/thimerosal-mercury-removed-from-us-flu-vaccines-acip.html

2. Gallagher A. ACIP votes against thimerosal vaccines for prevention of influenza. Drug Topics. June 27, 2025. Accessed July 24, 2025. https://www.drugtopics.com/view/acip-votes-against-thimerosal-vaccines-for-prevention-of-influenza

3. Gallagher A. CDC report finds no connection between thimerosal and autism. Drug Topics. June 25, 2025. Accessed July 24, 2025. https://www.drugtopics.com/view/cdc-report-finds-no-connection-between-thimerosal-and-autism

4. Gallagher A, Cleveland K. Q&A: How ACIP changes could reshape patient care. Drug Topics. July 5, 2025. Accessed July 24, 2025. https://www.drugtopics.com/view/q-a-how-acip-changes-could-reshape-patient-care