The EU's leading states are to restart their roll-out of the Oxford-AstraZeneca Covid-19 vaccine after Europe's medicines regulator concluded it was "safe and effective".
The European Medicines Agency (EMA) conducted a review after 13 EU states suspended use of the vaccine over fears of a link to blood clots and concluded that its benefits outweigh the risks.
The EMA found the vaccine was "not associated" with higher risk of clots but it said it would continue to study the possibility of such links.
The EMA investigation focused on a small number of cases of unusual blood disorders. In particular, it was looking at cases of cerebral venous thrombosis - blood clots in the head.
Germany, France, Italy and Spain said they would resume using the vaccine.
It is up to individual EU states to decide whether and when to re-start vaccinations using the AstraZeneca vaccine. Sweden said it needed a "few days" to decide.
French Prime Minister Jean Castex announced new measures for his country, saying the pandemic was clearly accelerating and a "third wave" of infections looked increasingly likely.
Castex, 55, said he would receive the jab himself today.
Decisions to suspend use of the vaccine sparked concerns over the pace of the region's vaccination drive, which had already been affected by supply shortages.
The World Health Organisation (WHO) on Thursday called on countries to continue using the vaccine, and is due to release the results of its own review into the vaccine's safety today.
More awareness to be raised around risks
The agency's executive director, Emer Cooke, told a news conference: "This is a safe and effective vaccine."
"Its benefits in protecting people from Covid-19 with the associated risks of death and hospitalisation outweigh the possible risks."
The EMA's expert committee on medicine safety, Cooke said, found that "the vaccine is not associated with an increase in the overall risk of thrombotic events or blood clots".
But the EMA, she added, could not rule out definitively a link between the vaccine and a "small number of cases of rare and unusual but very serious clotting disorders".
Therefore the committee has recommended raising awareness of these possible risks, making sure they are included in the product information. Additional investigations are being launched, Cooke added.
'Bad decision-making' in Europe - UK doctor
Thirteen EU countries suspended use of the vaccine, after reports of a small number of cases of blood clots among vaccine recipients in the region.
On Monday, the three largest EU members - Germany, France and Italy - said they were awaiting the results of the EMA investigation before deciding whether to resume their rollout of the jab.
They said they had opted to pause their use of the drug as a "precautionary measure".
"There were a few very unusual and troubling cases which justify this pause and the analysis," French immunologist Alain Fischer, who heads a government advisory board, told France Inter radio. "It's not lost time."
In Germany, the health ministry also pointed to a small number of rare blood clots in vaccinated people when justifying its decision. It postponed a summit on extending the vaccine rollout ahead of the EMA's announcement.
Other countries, such as Austria, halted the use of certain batches of the drug, while Belgium, Poland and the Czech Republic were among those to say they would continue to administer the AstraZeneca vaccine.
Decisions to halt rollouts of the AstraZeneca vaccine were criticised by some politicians and scientists.
A spokeswoman for Germany's opposition Free Democrats said the decision had set back the country's entire vaccination rollout. German Greens health expert Janosch Dahmen, meanwhile, argued that authorities could have continued using the drug.
Dr Anthony Cox, who researches drug safety at the UK's University of Birmingham, told the BBC it was a "cascade of bad decision-making that's spread across Europe".
The company said that there is no evidence of an increased risk of clotting due to the vaccine.
It said it had received 37 reports of blood clots out of more than 17 million people vaccinated in the EU and UK as of 8 March.
These figures were "much lower than would be expected to occur naturally in a general population of this size and is similar across other licensed Covid-19 vaccines", it said.
The director of the Oxford vaccine group which developed the Oxford-AstraZeneca jab, Professor Andrew Pollard, told the BBC on Monday that there was "very reassuring evidence that there is no increase in a blood clot phenomenon here in the UK, where most of the doses in Europe [have] been given so far".
British Health Secretary Matt Hancock this week urged people to "listen to the regulators" and to "get the jab".