Lockdown “has worked”, the Government’s chief scientific adviser has said.
But Sir Patrick Vallance warned it could take “weeks” for the virus to come down to very low levels.
He said that with one in 55 people currently estimated to have coronavirus, the country remains in a “difficult position”.
Meanwhile, he said that the vaccines would have “some effect” on transmissibility of the virus.
Sir Patrick told a Downing Street press conference: “Although things have slowed down, and actually we’re at a plateau or possible decreasing across the country, that’s not true everywhere.
“In some cases, there are still some increases.
“So we are at a position where the lockdowns have worked, they’ve slowed this down, they’ve reached a position where it has reached a plateau and is beginning to decline – and we see that in cases, we’re beginning to see that in hospital admissions and we’re beginning to see that in deaths – but it is early days.
“This isn’t coming down quickly, we remain at very high levels and it is going to take weeks for this to come down to really low levels.
“It is important with that, and the rollout of the vaccine programme, we start to see this changing, as the Prime Minister has said, and the vaccine programme should start to kick in so we can see the effects in the middle of February.
“But I want to remind us all that we remain in a difficult position at the moment and there are still very high levels.”
In the last 24 hours there were 25,308 cases picked up through testing and 1,725 new deaths reported.
Meanwhile, Professor Jonathan Van-Tam, deputy chief medical officer for England, said the scientific thinking was that the current coronavirus vaccines “couldn’t fail to have some effect on transmission”.
He said: “I don’t think there are clear data on the extent to which vaccines will reduce transmission at this point in time.
“There are multiple studies under way, predominately conducted by Public Health England in the UK, to look at this and I think we will get those data over time.
“I think as scientists we believe on first principles that vaccines with the very high level of effectiveness that we are seeing from the clinical trials really couldn’t fail to have some effect on transmission.
“And the question is really less ‘will they’ but ‘to what extent’?
“And I think when we have clarity on the extent, that will then open up a whole range of further questions about the future deployment of vaccines, after the JCVI priority groups 1-9 are completed, about how vaccines might play a role in keeping transmission low in the UK.”
Sir Patrick backed up Prof Van-Tam’s assertion that the vaccines currently being rolled out are likely to reduce transmission of Covid-19.
He said: “I think that is exactly right – there is going to be some effect on transmissibility.
“You don’t have vaccines to this degree of efficacy without there being some effect but we can’t put a number on it at the moment.
“I think it is really important that as these are rolled out across the world, we monitor and understand – Israel has started doing that and they are beginning to get some data out.
“They have said they won’t have any firm data for a few weeks yet and we’re going to be in the same position.”