Health secretary Matt Hancock has said he can't promise to 'play Santa' by delivering a vaccine by Christmas.Giving evidence to the Commons Science and Technology Committee this afternoon, he told MPs that his job was 'not to second guess' whether there will or won't be a vaccine by the end of the year.Mr Hancock was asked by Conservative MP Katherine Fletcher whether there would be a vaccine for coronavirus by Christmas, following positive results from the first stage of research into a vaccine