Brits may be forced to follow social distancing rules all year unless a vaccine is 85 per cent effective at stopping infections, ministers have been told.
Modellers have reportedly predicted another huge spike in coronavirus deaths if jabs fail to significantly cut infection rates.
Most experts believe vaccines will reduce transmissions by around 60 per cent under the best case scenario, the Sunday Telegraph reports.
Even if vaccines stopped 85 per cent of transmissions, the current lockdown would still have to remain in place until the end of May to prevent another surge in deaths, according to a University of Warwick paper.
The research was commissioned by the Scientific Pandemic Influenza Group on Modelling, which is a part of SAGE, and has been handed to Downing Street.
According to the Telegraph, modellers at the university warned: "Our predictions highlight the population-level risks of early relaxation leading to a pronounced wave of infection, hospital admissions and deaths.
"Only vaccines that offer high infection-blocking efficacy with high uptake in the general population allow relaxation of social distancing without a huge surge in deaths."
Dr Sam Moore, an epidemiological modeller at Warwick, told the Telegraph: "The vaccines are not going be 100 per cent effective at stopping serious disease.
"So if you manage to get, say, 85 per cent of people to take it and it turns out to be 90 per cent effective, that's still 25 per cent of people who could die from it, which is a lot of people."
Lifting restrictions in the middle of February - when the government is due to have vaccinated the country's top priority groups - would result in a spike in fatalities similar to last spring, the modelling suggests.
Even if vaccines have an 85 per cent efficacy by mid-February, deaths would reach just under 1,000 a day, compared with almost 1,500 a day if they had 60 per cent efficacy, it is claimed.
