Downing Street has refused to rule out keeping England's lockdown in place until the summer - but said Boris Johnson hopes this will be the "last national lockdown".
No10 said the Government wants to ease restrictions "as soon as it is safe to do so" but all evidence would be kept "under review", when asked if restrictions could last into the summer.
On a visit to flood-hit communities in the North West, Mr Johnson said it was "too early to say" when restrictions could be lifted.
The Prime Minister promised to review the national restrictions in mid February when he announced the third national lockdown earlier this month.
But Downing Street warned easing restrictions could only happen when transmission rates have fallen and pressure on the NHS has eased.
The Prime Minister's official spokesman also said the success of the vaccine rollout was key to leaving lockdown.
Asked if the PM intended to make this the final lockdown, his spokesman said: "We obviously hope it's the last national lockdown.
"I would point to what the Prime Minister has said previously that this is something that no Prime Minister would ever want to have to do but it has been necessary given the transmission rate of the virus and the pressure that the NHS is now sadly facing, and also sadly the number of people sadly dying from the disease.
"Of course it is our intention and our hope that this will be the last national lockdown but as we've said previously, we need to reduce the transmission rate of the virus, we need to relieve the pressure on the NHS and I would point to the vaccination programme that we have introduced and we have rolled out up and down the country as one of the ways out of this."
Asked to rule out the lockdown lasting into the summer, the spokesman said: "We will continue to keep all of the scientific evidence and data under review.
"It remains our position that we want to ease restrictions as soon as it is safe to do so but in order for us to do that, we need to see the transmission rates of the virus come down and we need to see the pressure on the NHS reduced."
Mr Johnson struck a cautious note on a visit to Didsbury, south Manchester, to see the floods caused by Storm Cristoph.
"I think it's too early to say when we'll be able to lift some of some of the restrictions," he told reporters.
"What we're seeing in the ONS data, in the REACT survey, we're seeing the contagiousness of the new variant that we saw arrive just before Christmas.
"There's no doubt it does spread very fast indeed."
