The Department of Health and Human Services (HHS), led by Secretary Robert F. Kennedy Jr., plans to mandate placebo-controlled clinical trials for all newly developed vaccines prior to their approval for public use, according to a statement provided to The Washington Post.

“Under Secretary Kennedy’s leadership, all new vaccines will undergo safety testing in placebo-controlled trials prior to licensure — a radical departure from past practices,” an HHS spokesperson said.

Placebo-controlled trials involve administering an inactive substance, such as saline, to a portion of participants while the rest receive the experimental vaccine. This method allows researchers to evaluate the vaccine’s effectiveness and safety relative to no treatment.

The department has not yet clarified which categories of vaccines will fall under the new requirement or how the policy will be implemented. However, an HHS spokesperson indicated the change would not affect the seasonal influenza vaccine, which the agency noted has been “tried and tested for more than 80 years.”

The policy shift comes amid ongoing internal reviews, including recent discussions about potentially removing the COVID-19 vaccine from the Centers for Disease Control and Prevention’s (CDC) recommended childhood immunization schedule. While the removal would not prohibit access to the vaccine, it would reverse a CDC recommendation in place since 2022, according to reporting by Politico.

Secretary Kennedy, who assumed leadership of HHS earlier this year, has expressed concerns over existing vaccine approval standards. While frequently critical of past safety protocols, the department emphasized that his focus is on reform, not rejection.

“Secretary Kennedy is not anti-vaccine — he is pro-safety, pro-transparency, and pro-accountability,” the agency told The Washington Post.