A further 1,564 people have died in the UK within 28 days of a positive Covid test – the biggest figure reported in a single day since the pandemic began.
It brings the total number of deaths by that measure to 84,767.
Dr Yvonne Doyle, medical director at Public Health England, said there have now been more deaths in the second wave than the first.
The prime minister warned there was a “very substantial” risk of intensive care capacity being “overtopped”.
Speaking to the Commons Liaison Committee, Boris Johnson said the situation was “very, very tough” in the NHS and the strain on staff was “colossal”.
He appealed to the public to follow lockdown rules, which require people in England to stay at home and only go out for limited reasons, such as for food shopping, exercise, or work if they cannot do so from home.
Similar measures are in place across much of Scotland, Wales and Northern Ireland.
Another 47,525 new cases have also been recorded, according to the government’s coronavirus dashboard.
Earlier, during Prime Minister’s Questions, Mr Johnson said lockdown measures were “starting to show signs of some effect” – but he refused to rule out extra restrictions in England, saying they were kept under “constant review”.
The number of people in the UK who have received a first dose of a vaccine has risen to 2,639,309 – up by 207,661 on Tuesday’s figure.
Perhaps the most distressing element about the latest Covid deaths is that the numbers are almost certainly going to rise from here.
People who are dying now are likely to have been infected three or so weeks ago, around Christmas time.
That was at a point when infection rates were rising quite steeply, so in the coming days and weeks we should, sadly, expect to see more deaths than this being reported.
Today’s figures are affected by the weekend, which sees delays in reporting deaths that tend to translate into higher figures from Tuesday onwards.
Currently around 800 to 900 people a day on average are dying once you take this into account.
But the figures also provide some hope. For the third day in a row the number of newly diagnosed infections are well below 50,000.
There have been several days where they have exceeded 60,000.
If that trend continues, and the number of new cases keeps coming down, that will eventually translate into the number of deaths falling.
But it is going to take some weeks for that to happen.
These are, as many have been saying, the darkest days of the pandemic so far.