U.S. Health Secretary Robert F. Kennedy Jr. is moving forward with a controversial order to eliminate thimerosal — a mercury-based preservative — from all vaccines distributed in the United States.
Thimerosal, which contains ethylmercury (a compound with a short half-life), has been used safely in vaccines since before World War II to prevent contamination in multi-dose vials. It’s currently found in only about 5% of adult flu shots. Scientific studies over decades have shown no evidence of harm from its use. Still, it has long been a lightning rod for anti-vaccine activists, who claim — without scientific backing — that thimerosal poses health risks.
Kennedy’s announcement follows a June recommendation from a restructured CDC vaccine advisory panel, which he overhauled by removing 17 existing members and appointing several individuals with ideologically aligned views, including a former anti-vaccine leader. The panel voted 5-1 in favor of removing thimerosal, following a disputed presentation that was revised after citing a nonexistent study.
“Injecting any amount of mercury into children when safe, mercury-free alternatives exist defies common sense,” Kennedy said. “Today, we put safety first.”
Though thimerosal is chemically different from the toxic methylmercury found in seafood — and is present in vaccines at levels lower than a small can of tuna — critics say Kennedy’s move could legitimize misinformation and create new challenges for global vaccine production and distribution.
The CDC director’s signature is typically required for such changes, but with no Senate-confirmed director in place, Kennedy holds that authority.
Now, Kennedy is urging global health organizations to follow the U.S. lead. “We urge health authorities worldwide to remove mercury from all vaccines to protect children globally,” he said.
While some praise the move as precautionary, many public health experts worry it sends mixed messages on vaccine safety.