The Centers for Disease Control and Prevention on Friday continued its endorsement of Moderna's COVID-19 vaccine for adults, now that U.S. regulators have given the shots their full approval.

The decision has little practical effect. Tens of millions of Americans have already gotten Moderna shots, following its emergency authorization by the Food and Drug Administration more than a year ago.

Earlier this week, the FDA gave the product full licensure, following the kind of rigorous, time-consuming review given to other vaccines.

While the FDA licenses vaccines, the CDC makes recommendations about how they should be used. So the CDC's Advisory Committee on Immunization Practices took up the matter on Friday.

The panel heard summaries of medical studies that showed the vaccine is working against the coronavirus and there is no evidence of new safety concerns. It voted unanimously to continue to endorse the shots, and the agency's director later signed off on the recommendation.

The Moderna vaccine, now being marketed under the name Spikevax, is licensed as a two-dose series for people 18 and older. Under earlier emergency use authorizations, additional doses can be given as additional doses for people with weakened immune systems or as half-dose boosters.