The U.S. Food and Drug Administration has approved a new lower-dose vaccine for active immunization against COVID-19 caused by severe acute respiratory syndrome coronavirus 2.

Moderna, over the weekend, announced that the U.S. Food and Drug Administration had approved its second-generation COVID vaccine, but only for specific populations: all adults 65 and over and those between 12 and 64 with at least one underlying risk factor as defined by the Centers for Disease Control and Prevention.

The biotech’s mRNA vaccines were lauded by the first Trump administration but now are caught up in government changes to vaccine rules.