Pressure on the NHS will not start to reduce until March, ministers have been warned - amid fears that new infections could be running at more than 250,000 a day.
Downing Street has been told by government scientists that the rollout of the vaccines is unlikely to cause the mortality rate to decline until later in February.
The vaccines are unlikely to have an impact in January because of the three-week lag time it takes before they have an effect.
Boris Johnson is under pressure from backbench MPs to announce he is lifting restrictions on 8 March.
Mark Harper, chair of the COVID Recovery Group of Tory MPs, said that after this date - three weeks after the deadline set to vaccinate the four most vulnerable groups - "what possible reason could there be for keeping severe restrictions in place a second longer".
But if the NHS is still running at or above capacity, Mr Johnson might be reluctant to follow their demand to remove severe restrictions at this point.
Some of Mr Johnson's backbenchers want those aged under 60 who will still be susceptible to the virus but not at that point vaccinated to be given the choice whether to return to a greater degree of normality.
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