WASHINGTON — Newly released data confirmed on Tuesday that Moderna’s coronavirus vaccine is highly protective, setting the stage for its emergency authorization this week by federal regulators and the start of its distribution across the country.

The Food and Drug Administration intends to authorize use of the vaccine on Friday, people familiar with the agency’s plans said. The decision would give millions of Americans access to a second coronavirus vaccine beginning as early as Monday.

The review by the FDA confirms Moderna’s earlier assessment that its vaccine had an efficacy rate of 94.1 percent in a trial of 30,000 people. Side effects, including fever, headache and fatigue, were unpleasant but not dangerous, the agency found.

The success of Moderna’s vaccine has become all the more crucial to fighting the pandemic as other vaccine efforts have faltered. The hopeful news arrives at a time of record-breaking numbers of coronavirus cases that are overwhelming hospitals and of an ever-increasing death toll, which reached a bleak milestone of 300,000 on Monday.

The data release is the first step of a public review process that will include a daylong meeting Thursday by an independent advisory panel of experts. They will hear from Moderna, FDA scientists and the public before voting on whether to recommend authorization. The panel is expected to vote yes, and the FDA generally follows the experts’ recommendations.

Distribution of about 6 million doses could then begin next week, significantly adding to the millions of doses already being shipped by Pfizer and BioNTech, the companies that developed the first coronavirus vaccine given emergency clearance Friday. Health care workers received the first shots Monday of the Pfizer-BioNTech vaccine, which has an efficacy rate of 95 percent.

The federal government signed deals last summer with Moderna and Pfizer to deliver a total of 200 million doses in the first quarter of 2021. Because both vaccines require two doses, those contracts guaranteed enough doses for 100 million people.

Last week the government announced that it had purchased another 100 million doses from Moderna for the second quarter, increasing the number of Americans who can be vaccinated to 150 million.

Both vaccines will be provided to the public free of charge.

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