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," 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.