NEW YORK — Advisers to the Centers for Disease Control and Prevention recommended on Thursday that millions of Americans, including those as young as 12, should get an omicron-targeting coronavirus booster shot to bolster defenses against serious illness and death during a potential fall or winter rise in COVID-19 cases.

The overall vote was 13-1 in favor of updated boosters from Moderna and Pfizer-BioNTech.

CDC Director Rochelle Walensky is expected to endorse the recommendation on the reformulated vaccine, allowing some clinicians, pharmacies and other providers to begin administering shots as early as this weekend.

Thursday’s action, along with authorization of the shots a day earlier by the Food and Drug Administration, marked another turning point in the pandemic and reflected the persistent struggle to tamp down illness and death 2½ years since the pandemic dawned.