France, Germany, Spain and Italy have said they are awaiting an investigation by the EU's regulator into reports of clots in a small number of recipients.
But other EU members, including Poland and Belgium, are continuing its use.
The European Medicines Agency (EMA) will release its findings on Thursday.
On Tuesday, the EMA said it was still "firmly convinced" of the benefits of the AstraZeneca drug. Its head, Emer Cooke, pointed out that blood clots highlighted by some countries were relatively common in the general population.
"I want to stress at present there is no indication that vaccination has caused these conditions," she said.
In a joint statement later on Tuesday, French President Emmanuel Macron and Italian Prime Minister Mario Draghi said the EMA's comments were "encouraging".
Meanwhile, experts from the World Health Organization (WHO) were also meeting on Tuesday but a spokesman stressed there was "no evidence" that the reported blood clots were linked to the vaccine.
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