U.S. to remove mercury preservative from flu shots following RFK Jr. vaccine panel vote

U.S. Health Secretary Robert F. Kennedy Jr. will officially mandate that vaccine manufacturers eliminate thimerosal from all vaccines, following a long-standing push from anti-vaccine activists.

Thimerosal—a mercury-based preservative—has been a focal point of vaccine misinformation campaigns for decades. The debate reached a tipping point in June when a restructured federal vaccine advisory panel, now filled with Kennedy's ideological allies, voted to recommend its removal.

The recommendation will take effect once Kennedy signs it.

Despite widespread use over many decades, there is no scientific evidence that thimerosal has caused harm. In the U.S., it was present in only about 5% of adult flu vaccines, where it helped prevent contamination in multi-dose vials.

“After more than two 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.

“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.”

Thimerosal is based on ethylmercury, which differs significantly from methylmercury, the form found in seafood. Ethylmercury is cleared from the body more quickly. A typical flu shot contains 25 micrograms of ethylmercury—less than the 40 micrograms of methylmercury found in a 3-ounce serving of canned tuna.

Thimerosal has been used in vaccines since before World War II. It was controversially removed from most childhood vaccines in 1999 as a precaution, though it remained in limited adult vaccines.

That move was criticized at the time by health experts who argued that scientific evidence did not support removal. Some warned it could send the wrong message and give ammunition to anti-vaccine campaigners—a concern that proved prescient as thimerosal remained a target for years.

The recent decision comes after Kennedy dismissed all 17 members of the CDC’s Advisory Committee on Immunization Practices (ACIP), which plays a central role in U.S. vaccine policy. He replaced them with eight new members, some of whom have ties to the anti-vaccine movement. One nominee later withdrew due to a conflict of interest.

The newly formed panel voted 5–1 (with one abstention) to recommend removing thimerosal after a contentious presentation from Lyn Redwood, a former leader of the World Mercury Project—an earlier incarnation of Kennedy’s Children’s Health Defense, an organization known for its anti-vaccine stance.