"The way in which the MHRA has worked is equivalent to all international standards," June Raine said.
Asked about whether Britain's departure from the European Union earlier this year had affected the speed of the authorisation, Raine said that the regulator had used provisions of European law, which apply until the end of the year when a Brexit transition period ends.
"We have been able to authorise the supply of this vaccine using provisions under European law, which exist until (Jan. 1). Our progress has been totally dependent on the availability of data in our rolling review and the rigorous assessment and independent advice we have received," Raine said.
(Reporting by Guy Faulconbridge and Kate Holton, writing by Alistair Smout, editing by Estelle Shirbon)