Pfizer’s Covid-19 vaccine passed a critical milestone on Thursday when a panel of experts formally recommended that the Food and Drug Administration authorize the vaccine. The agency is likely to do so within days, giving health care workers and nursing home residents first priority to begin receiving the first shots early next week.

The F.D.A.’s vaccine advisory panel, composed of independent scientific experts, infectious disease doctors and statisticians, voted in favor of emergency authorization for people 16 and older. Although the F.D.A. does not have to follow the advice of its advisory panel, it usually does.

With this formal blessing, the nation may finally begin to slow the spread of the virus just as infections and deaths surge, reaching a record of more than 3,000 daily deaths on Wednesday. The F.D.A. is expected to grant an emergency use authorization on Saturday, according to people familiar with the agency’s planning, though they cautioned that last-minute legal or bureaucratic requirements could push the announcement to Sunday or later.