HHS Secretary Robert F. Kennedy Jr. signed off on a recommendation from the CDC’s vaccine advisory panel July 23 to remove thimerosal from all influenza vaccines in the U.S.
Thimerosal is a mercury-based preservative introduced to flu doses in the 1930s to address bacterial contamination. Research has not demonstrated evidence that flu vaccines containing the preservative are harmful, but in 1999, the FDA directed vaccine makers to remove the preservative out of an abundance of caution, according to the CDC.
“After more than two decades of delay, this action fulfills a long-overdue promise to protect our most vulnerable populations from unnecessary mercury exposure,” Mr. Kennedy said in a statement. “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 2024, only 4% of flu shots administered in the U.S. contained the preservative, which is still used in multi-dose vials, according to data from Truveta.
The CDC’s Advisory Committee on Immunization Practices voted 5-1 in June to recommend only single-dose flu vaccines — which are all free of the preservative — be administered in the U.S. The vote marked one of the committee’s first actions since its membership was overhauled last month, when Mr. Kennedy dismissed all 17 members and appointed eight new ones. The HHS secretary has said the restructuring will reduce conflicts of interest with pharmaceutical companies. However, several healthcare industry groups have criticized the move, warning it could erode public confidence in vaccines.
