U.S. Health Secretary Robert F. Kennedy Jr. has formally directed vaccine manufacturers to eliminate thimerosal, a mercury-based preservative, from all vaccines distributed in the United States.
The directive follows a recommendation issued in June by a reconstituted federal vaccine advisory panel. That panel, now composed largely of Kennedy’s ideological allies, voted 5-1 in favor of removing thimerosal, with one member abstaining. The ruling becomes effective immediately upon Kennedy’s signature.
“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 safer alternatives exist, defies both common sense and public health responsibility.”
Thimerosal, an ethylmercury-based compound, has been used in vaccines since before World War II to prevent contamination in multi-dose vials. It differs chemically from methylmercury, the compound found in seafood, by breaking down more rapidly in the human body. A single dose of a flu vaccine containing thimerosal includes about 25 micrograms of ethylmercury—roughly half the amount found in a typical 3-ounce serving of canned tuna.
Although numerous studies over decades have found no evidence that thimerosal causes harm, it has long been targeted by anti-vaccine groups and misinformation campaigns. The preservative had already been phased out of most childhood vaccines by 1999 as a precautionary measure, and until now, remained in only about 5% of adult flu vaccines in the U.S.
The move to eliminate thimerosal reignites debate among health experts. Many scientists and physicians have criticized the decision, warning that it could reinforce vaccine hesitancy. Public health professionals have long maintained that the removal of thimerosal was not grounded in scientific necessity, but rather in public perception.
The decision comes on the heels of sweeping changes at the Centers for Disease Control and Prevention (CDC), where Kennedy dismissed all 17 members of its Advisory Committee on Immunization Practices. In their place, he appointed eight new members, including individuals affiliated with anti-vaccine advocacy groups. One appointee later withdrew following a conflict of interest review.
The panel’s recommendation relied in part on a presentation from Lyn Redwood, a former leader of the World Mercury Project, which preceded Kennedy’s own organization, Children’s Health Defense—a group widely known for spreading vaccine misinformation. Her presentation was later revised after it was found to reference a non-existent study.
Notably, a scheduled presentation from CDC scientists that reviewed thimerosal’s safety record was reportedly pulled at the direction of Kennedy’s office. With no Senate-confirmed CDC director in place, Kennedy currently serves in both capacities—as health secretary and de facto head of the CDC—and thus has the authority to implement the panel’s recommendations.
Critics argue that Kennedy’s decision politicizes vaccine oversight and undermines trust in public health institutions. Former New York Mayor Michael Bloomberg recently accused Kennedy of being a “peddler of junk science,” urging Republicans to reject his policies.
The implications of the U.S. ban are likely to extend beyond national borders. Many global vaccine programs still rely on multi-dose vials containing thimerosal due to cost and logistical constraints.
“With the U.S. now removing mercury from all vaccines, we urge global health authorities to follow this prudent example for the protection of children worldwide,” Kennedy added.
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