In this Dec. 29, 2020, file photo, Pat Moore, with the Chester County, Pa., Health Department, fills a syringe with Moderna COVID-19 vaccine before administering it to emergency medical workers and health care personnel at the Chester County Government Services Center in West Chester, Pa. (AP Photo/Matt Slocum, File)

Moderna said Tuesday its COVID-19 vaccine strongly protects kids as young as 12, a step that could put the shot on track to become the second option for that age group in the U.S.

Boxes containing the Moderna COVID-19 vaccine are prepared to be shipped at the McKesson distribution center in Olive Branch, Miss., Sunday, Dec. 20, 2020. (AP Photo / Paul Sancya, Pool)

Workers on Sunday began packaging shipments of the second COVID-19 vaccine authorized in the U.S., a desperately needed boost to efforts to bring the coronavirus pandemic under control.

In this July 27, 2020, file photo, a nurse prepares a shot as a study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway in Binghamton, N.Y. (AP Photo / Hans Pennink, File)

Much-needed doses are set to arrive Monday after the Food and Drug Administration authorized an emergency rollout of the vaccine developed by Moderna Inc. and the National Institutes of Health.

A man stands outside an entrance to a Moderna, Inc., building, Monday, May 18, 2020, in Cambridge, Mass. (AP Photo / Bill Sikes, file)

The FDA’s green light for emergency use is expected quickly. Moderna would then begin shipping millions of doses, earmarked for health workers and nursing home residents, to boost the largest vaccination effort in U.S. history.

In this July 27, 2020, file photo, nurse Kathe Olmstead prepares a shot that is part of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., in Binghamton, N.Y. (AP Photo / Hans Pennink, File)

If the FDA allows emergency use, Moderna expects to have 20 million doses ready for the U.S. by year’s end. Recipients will need two doses, so that’s enough for 10 million people. 

In this July 27, 2020, file photo, nurse Kathe Olmstead prepares a shot that is part of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., in Binghamton, N.Y. (AP Photo / Hans Pennink, File)

A second experimental COVID-19 vaccine — this one from Moderna Inc. — yielded extraordinarily strong early results Monday, another badly needed dose of hope as the pandemic enters a terrible new phase.