Federal Recommendations for Vaccines Containing Thimerosal Rescinded

HHS Secretary Robert F. Kennedy Jr has formally rescinded the federal recommendation for any flu vaccines containing thimerosal, building on previous moves that appear to question the safety of vaccines.¹ Thimerosal has previously been linked to autism by the antivaccine movement, though there has been no confirmed link between the mercury-based preservative and the neurodevelopmental condition.

The decision by Kennedy comes after the Advisory Committee on Immunization Practice (ACIP) voted to dismiss federal recommendations for all flu vaccines containing thimerosal. Kennedy made national news when he fired all 17 previous members of ACIP in 1 day, replacing them with members including vaccine skeptics, which Kennedy claimed was in an effort to restore public trust in vaccines.² The appointees included Martin Kulldorff, PhD, and Robert Malone, MD, who had previously expressed distrust in vaccines and doubt about the severity of COVID-19 during the health pandemic.

The number of flu vaccines containing thimerosal is low, accounting for only 5% of all flu shots distributed in the US in the last flu season.³ According to the CDC,⁴ thimerosal has previously been used to prevent the growth of germs in vials of vaccines that contain more than 1 dose. A move in 2001 removed thimerosal from all childhood vaccines in the US. The measles, mumps, and rubella; chickenpox; inactivated polio; and pneumococcal conjugate vaccines have never contained thimerosal.

Previous studies, including one conducted in 2010 by the CDC, have shown that there is no link between thimerosal and autism. Thimerosal was also not linked to neuropsychological delays in children, backed by studies conducted by the CDC and in Italy.

Individuals and care settings who will be affected by Kennedy’s decision include those in places where it is difficult to store many vaccines for long periods of time, necessitating multiple doses.¹ This would include mobile clinics in rural and remote areas and nursing homes. This move makes it so that insurance is no longer required to cover these vaccines, even if they remain available on the market.

HHS claims that manufacturers will be able to replace the supply of vaccines for this upcoming flu season so vaccinations can continue uninterrupted. The vaccines currently on the market will not be withdrawn but may not be available to receive due to the rescinding of the recommendation for the vaccine.

“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 statement.⁵ “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.”

It is unclear what the next steps are for ACIP and Kennedy when it comes to vaccines. The committee met on June 25 in the first of the traditional 3 annual meetings of the ACIP. The meeting included going over the efficacy of the COVID-19 vaccines, with panel members suggesting that the data could have led to an overrepresentation of the efficacy of the vaccine.⁶ It is possible that the COVID-19 vaccine could come under more scrutiny following Kennedy’s walking back of the CDC recommendation for healthy children and pregnant women to receive the COVID-19 vaccination. The American Academy of Pediatrics has chosen to publish its own vaccine schedule in response to the ACIP appointments.

References

1. Mandavilli A. Kennedy rescinds endorsements for some flu vaccines. New York Times. July 23, 2025. Accessed July 24, 2025. https://www.nytimes.com/2025/07/23/health/rfk-jr-flu-vaccines-thimerosal.html

2. Bonavitacola J. Vaccine skeptics among CDC vaccine panel replacements named by RFK Jr. AJMC^®. June 12, 2025. Accessed July 24, 2025. https://www.ajmc.com/view/vaccine-skeptics-among-cdc-vaccine-panel-replacements-named-by-rfk-jr

3. US ends use of flu shots with thimerosal in latest move by health secretary Kennedy. Reuters. July 23, 2025. Accessed July 24, 2025. https://www.reuters.com/legal/litigation/us-ends-use-flu-shots-with-thimerosal-latest-move-by-health-secretary-kennedy-2025-07-23/

4. Thimerosal and vaccines. CDC. December 19, 2024. Accessed July 24, 2025. https://www.cdc.gov/vaccine-safety/about/thimerosal.html

5. HHS adopts ACIP recommendation to remove thimerosal from all U.S. influenza vaccines. News release. HHS. July 23, 2025. Accessed July 24, 2025. https://www.hhs.gov/press-room/thimerosal-mercury-removed-from-us-flu-vaccines-acip.html

6. Steinzor P. CDC vaccine panel meets for first time after RFK Jr expelled former members. AJMC. June 25, 2025. Accessed July 24, 2025. https://www.ajmc.com/view/cdc-vaccine-panel-meets-for-first-time-after-rfk-jr-expelled-former-members