However, while repeating that the vaccine’s benefits outweigh risks, it cautioned that people should be aware of the “remote possibility” of rare blood clots occurring, and must seek immediate medical attention in case of symptoms.
“A causal link with the vaccine is not proven, but is possible and further analysis is continuing,” the European Medicines Agency (EMA) said in a statement.
EMA issued the statement after a hearing with a panel of independent external experts on Monday.
It spoke after several countries including Canada, Germany, France and Spain limited use of the drugmaker’s shot, after reports of a rare clotting condition following vaccination.
Investigations by EMA and several national authorities in the EU continue, after initial probes deemed the vaccine safe for use following reports of a brain clotting ailment known as cerebral venous sinus thrombosis (CVST).
A high proportion among the reported cases affected young and middle-aged women but that did not lead EMA to conclude this cohort was particularly at risk from AstraZeneca’s shot.
Women were generally more prone to CVST than men and twice as many women as men had received AstraZeneca’s shot in the EU so far, said EMA’s head of safety monitoring, Peter Arlett.
“This is why at this stage it is difficult to disentangle why there has been a preponderance of reports of this very rare potential side effect in younger women in particular,” he added.
EMA had analysed 62 such cases globally, consulting also with regulators in India, Brazil and Britain, and 44 of the cases had occurred in the European Economic Area (EEA).
It had looked into 14 deaths, though not all were associated with CVST, said Arlett. About 9.2 million people in the EEA had received the shot by the assessment’s cut-off date of March 22.
Arlett did acknowledge the blood-clotting incidence rate was higher than what was normally expected in the young and middle-aged. Though he did not quantify the difference, he said it did not justify a change in recommendation.
“If we look into individuals under 60, we do see more cases of (CVST) than we would expect to see from the background rate,” said Arlett.
Germany vaccine oversight body PEI said on Tuesday it had registered 31 cases of CVST, which resulted in nine deaths, out of some 2.7 million people who have received the AstraZeneca vaccine.
EMA said a few of the German cases happened after its cut-off date and had not yet been included in its analysis.