Moderna's vaccine is safe and 94 percent effective, regulators say, clearing the way for US emergency authorisation.
Photo: AFP
The analysis by the Food and Drug Administration's (FDA) means it could become the second coronavirus vaccine to be allowed in the US.
Americans across the country began receiving jabs of the Pfizer-BioNTech vaccine a day ago.
The US coronavirus death toll has passed 300,000, according to Johns Hopkins University.
Endorsement of the Moderna vaccine by FDA scientists was announced two days before the vaccine panel meets to discuss emergency approval.
What were their findings?
The 54-page document said there were "no specific safety concerns" and that serious adverse reactions were rare.
If approved by the team of experts later this week, and by the FDA's vaccine chief, shipments could begin within 24 hours.
The FDA found a 94.1 percent efficacy rate out of a trial of 30,000 people, according to the document they released.
The most common side effects included fever, headaches, and muscle and joint pain.
Last week, the FDA released similar data from Pfizer before voting to issue approval.
Moderna was founded in 2010 and so far has never had a product approved by the FDA.
The company's stocks have seen a nearly 700 percent increase so far this year.
How does it differ from the Pfizer jab?
The Moderna vaccine requires temperatures of around -20C for shipping - similar to a regular freezer.
The Pfizer jab requires temperatures closer to -75C, making transport logistics much more difficult.
Like the Pfizer jab, the Moderna vaccine also requires a second booster shot. Moderna's second jab comes 28 days after the first.
The company is based in Cambridge, Massachusetts, and has said that if approved, the "vast majority" of its vaccine would be manufactured there.
Pfizer's drug is being manufactured in several countries, including Germany and Belgium.
- BBC