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 the vaccine could lead to a return to normal next spring, 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.”
On Monday, NHS leaders announced that the health service will start testing all frontline staff twice a week to prevent the the spread of Covid by those who are asymptomatic. The daily figures showed 194 more deaths from the virus, bringing the UK total to 49,238.
Prof Van Tam said the vaccine breakthrough would not be soon enough to affect the currrent wave but stressed that a “much better horizon” could come by the end of spring, saying: “We have to keep pressing hard for now. We’ve seen a swallow, but this is very much not summer. It would be a colossal mistake on the part of any one of us to relax at this point.”
Peter Horby, professor of emerging infectious diseases and Global Health in the Nuffield Department of Medicine, University of Oxford was among the scientists celebrating on Monday.
He said: “This news made me smile from ear to ear. It is a relief to see such positive results on this vaccine and bodes well for Covid-19 vaccines in general. Of course we need to see more detail and await the final results, and there is a long long way to go before vaccines will start to make a real difference – but this feels to me like a watershed moment.”