A senior official at Europe’s medicines regulator has said there is a clear “association” between AstraZeneca’s Covid-19 vaccine and very rare blood clots in the brain, though the direct cause of the clots is still unknown. The European Medical Agency (EMA) said in a statement after the comments by Marco Cavaleri, chair of its vaccine evaluation team, that it was still conducting a review of the vaccine and expected to announce its findings on Wednesday or Thursday. An AstraZeneca spokesman declined to comment on Cavaleri’s remarks, which he made in an interview with Italian newspaper Il Messagero that was published on Tuesday. “In my opinion, we can now say it, it is clear that there is an association (of the brain blood clots) with the vaccine. However, we still do not know what causes this reaction,” Cavaleri said, without giving evidence to support his comments.