U.S. To Eliminate Mercury-Based Preservative From All Flu Vaccines

The Department of Health and Human Services announced Wednesday that it will fully eliminate thimerosal, a mercury-based preservative, from flu vaccines, following a formal recommendation by a federal advisory panel.

The move marks a significant shift in vaccine policy after years of mounting concern over mercury exposure, particularly in children. 

Last month, the ACIP voted to limit flu vaccines to only those free of thimerosal. The mercury-containing preservative, largely phased out of childhood vaccines by 2001, still lingers in some multi-dose flu shots. HHS Secretary Robert F. Kennedy, Jr., on Tuesday signed the advisory board’s recommendations, the department said Wednesday. -Just the News

“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.”

Kennedy added: “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.”

Thimerosal, first introduced in the 1930s to prevent microbial contamination in multi-dose vaccine vials, was largely removed from childhood immunizations by 2001. However, it remained in some adult flu shots and doses provided through multi-use vials, which have been favored for their efficiency in mass vaccination settings.

The renewed push to remove thimerosal gained traction in the late 1990s, after the FDA Modernization Act of 1997 mandated a review of mercury in medical products. In recent decades, growing public and scientific scrutiny of cumulative mercury exposure – particularly among infants and pregnant women – has led to calls for reform.

According to HHS, 96 percent of flu vaccines for the 2024–2025 season are already thimerosal-free, meaning the transition to single-dose, preservative-free vials is unlikely to disrupt supply. Vaccine manufacturers have assured the agency that they can meet demand for both adult vaccinations and the Vaccines for Children program.

Wednesday’s announcement positions the United States as a leader in vaccine safety standards, and signals a broader shift in public health priorities after years of debate over thimerosal’s role. While major health organizations have long maintained that the preservative is safe at the levels used in vaccines, the move reflects a precautionary stance toward reducing avoidable mercury exposure – especially when alternatives are readily available.