Europe's drug regulator said on Friday it had started reviewing reports of a bleeding condition in people who had received AstraZeneca's COVID-19 vaccine and was also looking into Johnson & Johnson's shot over blood clots.

Four serious cases of rare blood clots with low platelets, one of which was fatal, have been reported after inoculation with J&J's vaccine from its Janssen unit, the European Medicines Agency said, adding five cases of capillary leak syndrome linked to AstraZeneca's vaccine were reported.