The EU's drug regulator approved the Moderna coronavirus jab on Wednesday, the bloc's second and a shot in the arm for Europe's slow-moving vaccine roll-out.
In a long-awaited decision, the Amsterdam-based European Medicines Agency (EMA) gave the green light for the US firm's vaccine for use on people over 18.
Criticism has mounted of the EU's sluggish start to its vaccination campaign since the first vaccine, by Pfizer-BioNTech, was authorised in late December.
Europe is lagging far behind the United States, Britain and Israel in terms of numbers of people vaccinated, with Covid-19 cases soaring across the continent.
"This vaccine provides us with another tool to overcome the current emergency,” EMA Executive Director Emer Cooke said in a statement.
European Commission chief Ursula von der Leyen said the EU was now "working at full speed" to make it available across the 27 countries of the bloc.
"Good news for our efforts to bring more Covid-19 vaccines to Europeans!" she said on Twitter.
The Commission must formally rubber stamp approval for the vaccine but that could come within hours.
The EMA's one-year conditional marketing authorisation is for two injections of the Moderna vaccine into the arm, 28 days apart.
The EMA said that its human medicines committee, with experts drawn from all 27 countries, had "thoroughly assessed the data on the quality, safety and efficacy of the vaccine" and recommended authorisation "by consensus".
"This will assure EU citizens that the vaccine meets EU standards" to underpin confidence in vaccination campaigns, it added.
- 'Gigantic challenge' -
National capitals have been piling pressure on the Amsterdam-based EMA to authorise the Moderna vaccine.
The regulator failed to decide on approval at a meeting on Monday, which had been brought forward from January 12, and experts had to meet again on Wednesday.
The EMA said it had in the intervening time been "working hard to clarify all outstanding issues with the company".
The EU began vaccinations on December 27 but the pace has been slow, with the Netherlands on Wednesday becoming the final country in the bloc to start.
European Council chief Charles Michel said late on Tuesday that leaders would hold a virtual summit on the health crisis later this month.
Michel said that delivering vaccines to the EU's almost 450 million people was a "gigantic challenge".
But he insisted that "alongside member states, the European Commission is working night and day to make sure we can increase the number of vaccines available" -- while "respecting the independence of the medicines agency".
Moderna's jab was found to be 94.1 percent effective in preventing Covid-19 compared to a placebo in a clinical trial of 30,400 people, performing slightly better in younger adults compared to the elderly.
The United States uses it alongside the Pfizer-BioNTech vaccine, while Britain is using Pfizer's and one developed by UK pharmaceuticals giant AstraZeneca and Oxford University.
The EMA said last week that the Oxford-AstraZeneca vaccine is unlikely to get a green light in the EU this month.
The fact that the watchdog moved from London to Amsterdam after Brexit has itself fuelled commentary about how Britain had been able to move faster after leaving the EU.