A Department of Health and Human Services spokesperson called the move "a radical departure from past practices."

The top US health department plans to require placebo testing for all vaccines in an effort to offer "straightforward" public health information, but experts say such testing could limit availability and raise ethical concerns.

A major change in the way HHS plans to evaluate vaccine safety is raising fears that approvals will become unnecessarily onerous and make shots for COVID-19 and other viruses scarcer. Why it matters: The change under Secretary Robert F.