The European Union's drugs regulator is investigating whether any of the three Covid-19 vaccines approved in the bloc might be linked to a blood clotting deficiency that can cause internal bleeding.
The European Medicines Agency (EMA) said on Friday that several cases of immune thrombocytopenia, a lack of platelets in the blood that can lead to bleeding and bruising, had been reported under its vaccine safety monitoring process.
"It is not yet clear whether there is a causal association between vaccination and the reports of immune thrombocytopenia," the EMA said.
The agency said it would assess reports of the condition in people who had received the Pfizer/BioNTech, AstraZeneca or Moderna vaccines.
European vaccination programmes have been upset in the last two weeks by reports that recipients of the AstraZeneca inoculation have suffered blood clots.
The EMA has said there is no indication that the events were caused by the vaccination, a view that was echoed by the World Health Organisation on Friday. AstraZeneca also said it had found no evidence of increased risk of deep-vein thrombosis.
