The EU's medicines regulator has said it remains "firmly convinced" that the benefits of the Oxford-AstraZeneca Covid-19 jab outweigh the risks.
It reiterated that there was "no indication" the vaccine causes blood clots, after several leading EU states paused their rollouts, reports the BBC.
European Medicines Agency (EMA) head Emer Cooke said the body stood by its decision to approve the vaccine.
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.
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," Cooke 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.