Pharmaceutical giant Johnson & Johnson submitted its single-shot coronavirus vaccine to U.S. regulators Thursday afternoon for emergency use authorization after the vaccine was shown to be robustly effective against illness in a global trial — and especially at preventing severe disease and death.

The submission is “a pivotal step toward reducing the burden of disease for people globally and putting an end to the pandemic,” Paul Stoffels, chief scientific officer of Johnson & Johnson, said in a statement. If the vaccine receives regulatory clearance by the Food and Drug Administration, it would be the third authorized shot in the United States — a much-needed addition to the tools public health officials have to build immunity as virus variants spread.

FDA officials announced that outside experts would discuss the vaccine at a public meeting three weeks from now, on Feb. 26.

In a news release last week, the company announced its vaccine was 66 percent effective overall at preventing moderate to severe illness in a global clinical trial. It offered the best protection against severe cases of disease, proving 85 percent effective. There were no hospitalizations or deaths among people who received the vaccine. That result held up even in the South Africa portion of its trial, where a concerning virus variant that has shown the ability to evade some immunity has become dominant.

The data has not been peer-reviewed or published but will be carefully reviewed by career FDA scientists and an external panel of experts who will determine if the vaccine meets the safety and efficacy requirements for emergency use.

Stoffels said the company would be ready to ship doses immediately upon authorization but did not specify the number — which government officials have told The Washington Post could be in the single-digit millions.

If the vaccine follows the same trajectory as the Pfizer-BioNTech and Moderna vaccines that were authorized late last year, an expert panel of advisers to the FDA would consider the data at a full-day meeting near the end of this month. The FDA is guided by that panel’s deliberations. For the other vaccines, it acted within a day of the advisory committee meeting.

The easier logistics of the Johnson & Johnson vaccine, which can be stored at refrigerator temperatures for several months and requires only a single shot, would make it a welcome addition amid the drive to accelerate vaccinations as variants loom.

Some non-priority District residents are receiving coronavirus vaccines just before they are set to expire. (Allie Caren/The Washington Post)

In the meantime, the FDA said Thursday it will propose draft guidelines on how manufacturers of coronavirus vaccines, therapeutics and diagnostic tests should deal with new variants of the virus.

Janet Woodcock, the FDA’s acting commissioner, pledged to pursue streamlined processes to get updated products to health-care personnel, saying the FDA would not “create obstacles” to authorizing tools that could be useful.

She said in a statement that the FDA has anticipated the emergence of variants and does not believe there will be “the need to start at square one with any of these products.”

In a call with reporters, Woodcock stressed that the currently authorized vaccines are highly effective but that the agency needs to prepare for “all eventualities” and is doing scenario planning that includes the possibility of variants becoming dominant. She said the FDA plans to respond “as quickly as possible.”