The European Union medicines regulator has reiterated there is "no indication" that the Oxford-AstraZeneca Covid jab causes blood clots, after several countries paused their rollouts.
European Medicines Agency (EMA) head Emer Cooke said she remained "firmly convinced" that the benefits of the vaccine outweighed any risks, reports the BBC.
An investigation into cases of clots in a handful of recipients is ongoing.
The World Health Organization has urged countries not to halt vaccinations.
Vaccine safety experts from the WHO are also meeting on Tuesday to review the Oxford-AstraZeneca jab.AstraZeneca says a review of 17 million people who received doses in Europe found there were 37 cases of people who had developed blood clots.
The EMA says the number of blood clots reported in vaccinated people is no higher than that seen in the general population.
"We know that many thousands of people develop blood clots in the EU so what we want is to establish whether these events are caused by the vaccine or by other causes," Emer said.
"While the investigation is ongoing, currently, we are still firmly convinced that the benefits of the AstraZeneca vaccine in preventing Covid-19, with its associated risks of hospitalisation and death, outweigh the risks," she added.
Results from the EMA's investigation are due to be released on Thursday.