"The headline result is the vaccine works and that's very exciting," Vallance said during a news conference with Prime Minister Boris Johnson.
Chief Medical Adviser Chris Whitty, answering the same question, said there was always scientific debate about virtually everything.
"The key thing from our point of view is to leave this in the hands of the regulator ... They will make an assessment with lots of data that is not currently in the public domain on efficacy and on safety," Whitty said.
(Reporting by William James and Estelle Shirbon; editing by Stephen Addison)
