U.S. Health and Human Services Secretary Robert F. Kennedy Jr. said on Tuesday that Moderna has agreed to a true placebo-controlled trial of its new COVID-19 vaccine. While noting that he was aware of concerns about the Food and Drug Administration's limited approval of the new mRNA vaccine for high-risk populations,

The FDA's approval was based on a study of 11,400 people age 12 and older that compared the new low-dose vaccine with Moderna's existing vaccine. It found the new vaccine was safe and was at least as effective - and more by some measures - than the original shot, the company said.

Moderna's mNexspike COVID vaccine approved by FDA for older adults and at-risk groups after Phase 3 trial shows improved efficacy and safety profile.