Germany, France and Italy have stopped the rollouts of the Oxford-AstraZeneca vaccine, after a series of incidents in Europe involving blood clots.
The countries have joined several smaller European nations who have halted vaccinations as a precaution while checks are made.
The World Health Organization, WHO, has said there is no evidence that the incidents are caused by the vaccine.
It said it was reviewing reports relating to the jab, but it was important vaccinations continued.
It added that it was good practice to investigate potential adverse events.