On Oct. 21, the Centers for Disease Control and Prevention (CDC) joined the U.S. Food and Drug Administration (FDA) in approval of a single booster dose of the Moderna and Johnson & Johnson vaccines in certain populations who completed a full vaccine series of either vaccine.On Oct. 21, the Centers for Disease Control and Prevention (CDC) joined the U.S. Food and Drug Administration (FDA) in approval of a single booster dose of the Moderna and Johnson & Johnson vaccines in certain populations who completed a full vaccine series of either vaccine.