Key dates in coronavirus vaccine approval and distribution

Vaccine priorities

A panel of experts voted to prioritize the distribution of the coronavirus vaccine to health care workers and residents of nursing homes.

The next few weeks will likely see a lot of action as U.S. regulators assess COVID-19 vaccines and state officials get ready to start giving the shots to people. Shots for at most 20 million people are expected by year's end.

— Dec. 1: Centers for Disease Control and Prevention advisory committee votes on who should be first in line to receive vaccinations; the panel voted 13-1 to recommend that health care workers and nursing home residents get priority in the first days of any coming vaccination program, when doses are expected to be very limited; the two groups encompass about 24 million people out of a U.S. population of about 330 million.

— Dec. 4: Deadline for states to submit requests for doses of the Pfizer/BioNTech vaccine and where they should be shipped.

— Dec. 10: Food and Drug Administration advisers meet to debate if there's enough evidence for emergency use of the Pfizer vaccine. Sometime after the meeting, the FDA will weigh those recommendations in deciding whether to authorize emergency use.

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— Dec. 11: Deadline for states to submit requests for doses of the Moderna vaccine and where they should be shipped.

— Dec. 17: FDA advisers meet to debate evidence behind the Moderna vaccine. The FDA will weigh those recommendations in deciding whether to authorize emergency use sometime after the meeting.

Current estimates project that no more than 20 million doses of each vaccine will be available by the end of 2020. And each product requires two doses. As a result, the shots will be rationed in the early stages. (Story continues)

A COVID-19 test is handed through the vehicle window at a mobile testing site in Long Beach, Calif., Tuesday, Dec. 1, 2020. (AP Photo/Ashley Landis)

— Within 24 hours: "Phase 1a" of rollout begins. Private shippers would send shots to each state's predetermined locations, such as hospitals. Health workers would give first shots to people per states' plans, with people working in health care likely at the front of the line.

— Second doses: For Pfizer's vaccine, the second dose is given three weeks after the first. For Moderna's, the second shot comes four weeks after the first.