In a press release, the European agency reports that "the discussion by the EMA's Committee for Medicinal Products for Human Use on the [Moderna] vaccine has not been concluded and will continue on Wednesday", noting that its "experts are working hard to clarify outstanding issues with the company".

The discussions will continue on Wednesday, 6 January to give experts more time to analyse the clinical and laboratory data made available to them by the US pharmacist.

If a positive conclusion is reached, the Moderna vaccine will be the second to receive the "green light" from European Union (EU) researchers after the approval on 21 December of the drug developed by pharmacists Pfizer and BioNTech, which has been in use in Europe since last week.

The committee has also opened since 1 December last year two real-time review processes of the vaccines developed by Janssen, a subsidiary of Johnson & Johnson and Oxford University, and Astrazeneca, although neither has requested a conditional authorisation for use of the drug in the EU.