The Claim in Context 

In June 2025, the Advisory Committee on Immunization Practices (ACIP) voted to recommend banning thimerosal, a preservative, from all vaccines because of its mercury content. Extensive research proves that thimerosal is a safe ingredient in vaccines, and it does not cause neurological problems or autism. Banning vaccine ingredients without solid scientific reasons sets a dangerous precedent and ultimately makes children less safe. 

Key Facts 

  • Thimerosal is an extensively studied preservative used in a small percentage of multi-dose vials of the influenza vaccine administered in the U.S. It has not been in any routine childhood vaccines since the early 2000s.   
  • Thimerosal is an ethyl mercury. Toxicity concerns relate to methyl mercury, a different form of the element that has never been used in vaccines.
  • In 2001, thimerosal was removed from all routine childhood vaccines because misleading claims about different types of mercury were eroding public trust in vaccine safety. Pediatric and medical organizations — including AAP — recommended removing thimerosal because the risks of children going without vaccines had become greater than the benefits of thimerosal as a vaccine ingredient.  
  • AAP's assessment of the best available evidence has always been, and continues to be, that thimerosal is a safe additive in appropriate amounts. 
  • Extensive research has demonstrated that thimerosal is safe. There is no evidence that thimerosal causes autism or other neurodevelopmental disorders. Autism rates actually rose after thimerosal was removed from childhood vaccines.
  • Decisions about which vaccine ingredients are safe should not be based on disproven presumptions, but rather on medical evidence.  

Evidence Snapshot

Numerous studies conducted over many years in multiple countries have confirmed that thimerosal is safe. Banning vaccine ingredients without cause increases the perceived risk of vaccines and fuels vaccine hesitancy.  


Experts Say:

“There is no evidence that thimerosal has adverse neurological or neurodevelopmental adverse outcomes when used as a preservative in vaccines. This fact was definitively determined years ago, and the FDA, the CDC, and many academic institutions have excellent reviews of the safety of thimerosal-containing vaccines in children. Raising this topic now has only one purpose- to sow distrust in vaccines in general and in the process to determine vaccine safety.” 


— James Campbell, MD, MS, FAAP, Member, AAP Committee on Infectious Diseases 

Why It Matters

Pediatricians should be able to trust the ACIP to make evidence-based recommendations to protect children’s health. It is reckless and dangerous for government agencies to undermine public trust in vaccines. 

Resources for Further Information 

Last Updated

07/15/2025

Source

American Academy of Pediatrics