Europe’s drugs regulator is reviewing possible links between blood clots and Johnson & Johnson’s coronavirus vaccine.

It comes after four serious cases of rare clots with low platelets were reported after inoculation, one of which was fatal, according to the European Medicines Agency (EMA).

The Johnson & Johnson (also known as Janssen) vaccine has been rolled out in the European Union and the US in recent months, having proved 67% effective in preventing COVID-19 and completely effective at preventing hospital admissions and death from the virus during trials.

It stands out from the other jabs being used because only one shot is needed, rather than two.

The UK has ordered 30 million doses, but it has not yet been approved by the regulator.

Both the EMA and the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) have investigated links between rare clots and the Oxford-AstraZeneca vaccine, but this is the first formal disclosure that the Janssen jab is also being looked into.