The European Medicines Agency (EMA) on Thursday approved Johnson & Johnson's single-shot COVID-19 vaccine, making it the fourth licensed vaccine for use in the bloc.

Others that have already been approved for use are those from Pfizer, AstraZeneca and Moderna.

The medicines regulator said it was recommending the vaccine to be used on persons above 18 years old "after a thorough evaluation" of Johnson & Johnson's data found the vaccine met the criteria for efficacy, safety and quality.

"With this latest positive opinion, authorities across the European Union will have another option to combat the pandemic and protect the lives and health of their citizens," said Emer Cooke, EMA's Executive Director, adding, "this is the first vaccine which can be used as a single dose."

EMA said trials had proved that the vaccine had a 67% efficacy.

"The safety and effectiveness of the vaccine will continue to be monitored as it is used across the EU, through the EU pharmacovigilance system and additional studies by the company and European authorities," the regulator said.