But the framework has perhaps created as much confusion as clarity. Broadly, the FDA said it will limit approval of Covid-19 vaccines to people 65 and older and to those at risk for severe Covid outcomes, and will require vaccine makers to conduct clinical trials investigating whether the shots benefit healthy adults and children.

The change marks a shift in the Food and Drug Administration’s policy on approving COVID-19 vaccines, which the new commissioner described as a “one-size-fits-all regulatory framework.”

The U.S. Food and Drug Administration on Tuesday said it plans to require new clinical trials for approval of annual COVID-19 boosters for healthy Americans under age 65, effectively limiting them to older adults and those at risk of developing severe illness.