The trial results come from a Phase 3 study of 43,538 participants in six countries, with most having now received two doses. The case split between vaccinated individuals and those who received the placebo indicates a vaccine efficacy rate above 90 per cent, at seven days after the second dose, researchers said.
Scientists said this means protection is achieved 28 days after the initiation of the first vaccination. However, they warned that, as the study continues, the final vaccine efficacy percentage may vary.
Mr Johnson said he was “buoyantly optimistic about the prospects of this country next year” but warned: “I just don’t want to let people run away with the idea that this development is a home run, a slam dunk, a shot to the back of the net yet. There is a long way before we have got this thing beat.”
Asked about suggestions that the vaccine could lead to a swift return to normality, Prof Van Tam likened Britain’s situation to a train journey in precarious conditions, saying: “It’s wet, it’s windy, it’s horrible. And two miles down the tracks two lights appear, and it’s the train and it’s a long way off – and we’re at that point at the moment.”
Dr Tedros Adhanom Ghebreyesus, the director general of the World Health Organisation, said: “We welcome the encouraging vaccine news from Pfizer and BioNTech and salute all scientists and partners around the world who are developing new safe, efficacious tools to beat Covid-19.”