Europe's medicines regulator gave the go ahead on Friday for an extra sixth dose to be extracted from the Pfizer-BioNTech COVID-19 vaccine vials, lifting the number of available shots at a time when supplies are short.

EU countries started inoculating people with the Pfizer-BioNTech vaccine two weeks ago, after the European Medicines Agency (EMA) recommended the shot's conditional approval under an authorisation which allows five doses to be extracted from each vial.