Berlin (dpa) - A number of European Union countries were rolling out the Oxford/AstraZeneca Covid-19 vaccine once again on Friday, lifting their suspensions after receiving new safety assurances from the EU's medicines regulator.

The vaccinations resumed in several states in Germany, while in neighbouring France Prime Minister Jean Castex announced that he himself would receive the injection on Friday.

Governments are trying to bolster damaged public confidence in the AstraZeneca vaccine after its use was halted starting late last week in several Nordic countries over cases of blood clots in a handful of recipients.

Then other nations such as Germany, France, Italy and Spain ordered their own pauses to the AstraZeneca jab pending a new assessment by the European Medicines Agency (EMA).

The regulator said on Thursday evening that the vaccine was "safe and effective" after an extensive review of possible blood clot risks.

The EMA concluded that the vaccine was not associated with an increase in the overall risk of thromboembolic events or blood clots, although it could not definitively rule out a link between cases of rare, very serious clotting disorders, mostly in younger women.

With that asterisk still hanging over the jab, France and Germany were among the governments to issue advice on who should get it.

France's top health authority on Friday recommended the AstraZeneca vaccine only for people over the age of 55 due to the possible increased risk of certain type of brain clot in younger people.

In Germany, authorities have issued a warning for women under the age of 55 that it may be associated with a risk of cerebral blood clots.

Italy, Latvia and Bulgaria were also to start administering the vaccine again on Friday, although other EU countries such as Spain and Sweden said they would need a few more days.

But amid the flurry of negative headlines Prime Minister Boris Johnson said on Thursday he had no doubt about the safety of the AstraZeneca shot and, to prove it, he would have it administered to him on Friday.

The World Health Organization (WHO) has endorsed the vaccine, which has a an efficacy of 63 per cent against symptomatic infections.

The two-dose shot is one of four Covid-19 vaccines to receive approval by the European Union, which is struggling to ramp up its inoculation drive after a slow start since it kicked off in late December.