The US Food and Drug Administration will require all new vaccines go through placebo-controlled studies before they are approved, a policy change that could alter how novel immunizations are developed.

“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,” the Department of Health and Human Services (HHS) said in a statement to CNN.

The Department of Health and Human Services says it will require new vaccines to be tested against a placebo, which could complicate and delay Food and Drug Administration approval of many vaccines.