Life in the UK could return to normal by summer if vaccines prove effective, according to a government scientific adviser.
Dr Mike Tildesley, a member of Sage subgroup the Scientific Pandemic Influenza Group on Modelling (Spi-M), said scientists believed vaccines would block transmission of coronavirus, but it was not yet known by how much.
But he said if vaccines prove effective, lockdown restrictions could start to be eased in March.
Speaking to BBC Radio 4's Today programme he said: "If we think optimistically, if we follow the trajectory of the rollout of the vaccine... then hopefully we can be easing out of these controls that we've got in place sometime in March.
"But I think even with that optimistic situation, it needs to be done relatively gradually.
"The danger is of course as we do start to unwind controls then we offset the gains that we get from vaccination, so we need to be very careful.
"But if the vaccine rollout continues at high levels, and we do find that actually these vaccines are very good at blocking transmission as well as preventing severe infection, then we're in a good position.
"Hopefully by the summer we can get back to something pretty close to what we have seen before the pandemic was normal."
Dr Tildesley said the UK did "need to have these vaccines being pretty good at blocking transmission".
He added: "We will start to gain much more information about that in the next month as we follow people who have been vaccinated and see what their ability is to pass on the virus should they get infected.
"It's fairly early days yet."
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Asked if vaccines needed to 100% block transmission, he said: "I think probably not quite close to 100%, but I think if we have somewhere in the region of say 70 to 80%, then probably we're in a good place."
He said vaccines are not 100% protective and some people would not have the vaccine.
He said: "As we ease the controls you get more mixing, and even if a lot of the vulnerable population are protected then they have more risk, those that are not protected have more risk.
"So that's why a gradual easing of restrictions, combined with uptake of vaccine, is really what's needed."
