Boris Johnson has said England’s emergence from national lockdown will be “gradual” rather than in one “big bang”.
MPs are expected to approve legislation on Wednesday that will allow the government to keep the restrictions in place until March 31.
Speaking in the Commons, the prime minister said he had “no choice” but to bring in the new rules given the surge in infections triggered by the new variant of coronavirus.
Johnson said the eventual lifting of the lockdown would be “steady” and “controlled”.
“We are in a sprint. A race to vaccinate the vulnerable faster than the virus can reach them,” he said.
Johnson has set a target to vaccinate 13m people by February 15, including the over-70s and most vulnerable. This would require two million people to be vaccinated a week.
He told MPs if this was achieved there would then be “substantial opportunities” to “relax restrictions” from that date.
“As was the case last spring, our emergence from the lockdown cocoon will not be a big bang but a gradual unwrapping,” he said.
“That is why the legislation this House will vote on later today runs until March 31, not because we expect the full national lockdown to continue until then, but to allow a steady, controlled and evidence-led move down through the tiers on a regional basis – carefully, brick by brick, as it were, breaking free of our confinement but without risking the hard won gains that our protections have given us.”
Keir Starmer, the Labour leader, has said his party will vote in favour of England’s third lockdown.
But he said the return to lockdown was only needed because the government had repeatedly been too slow to act.
“This is not just bad luck, it’s not inevitable, it follows a pattern,” Starmer told MPs.
“The situation we face is clearly very serious, perhaps the darkest moment of the pandemic.”
Education secretary Gavin Williamson will later on Wednesday set out his plans for England’s pupils after schools were closed as part of the lockdown, with GCSE and A-level exams cancelled.
Johnson said the decision to shut schools came so late as the government wanted to do “everything in our power” to keep schools open until every other option had been exhausted.
He said schools “may” reopen after the February half-term, but promised they would be the “very first things to reopen” when restrictions could be loosened.
Data from the Office for National Statistics (ONS) has suggested 1.1 million people in England had Covid-19 between December 27 and January 2.
Chris Whitty, England’s chief medical officer, warned on Tuesday some restrictions may have to be introduced again next winter.