Video report by ITV News Political Correspondent Daniel Hewitt
England is to enter another national Covid-19 lockdown from tonight, which will remain in place until mid-February, the Prime Minister has announced.
In effect, the country will return to the first lockdown in March - with people only allowed to leave their house for essential reasons and the majority of schools closed.
The clinically extremely vulnerable are also being advised to begin shielding again, with those affected set to receive letters “shortly”.
Watch: ITV News special coverage of the prime minister's address
The restrictions are expected to last until at least February 15, with the PM suggesting the country might then be able to start "steadily" moving out of lockdown with progress expected on the mass vaccination programme.
"By the middle of February, if things go well and with a fair wind in our sails, we expect to have offered the first vaccine dose to everyone in the four top priority groups identified by the Joint Committee on Vaccination and Immunisation," the PM said.
"That means vaccinating all residents in a care home for older adults and their carers, everyone over the age of 70, all frontline health and social care workers, and everyone who is clinically extremely vulnerable."
What the new rules are:
Boris Johnson outlined the strengthened restrictions in a televised address to the nation on Monday, amid warnings the NHS could be overwhelmed within three weeks if action was not taken.
It comes as the number of Covid patients in hospital in England rose to nearly 27,000 - a figure 40% higher than the peak level in April.
On December 29 "more than 80,000 people tested positive for Covid across the UK", the number of deaths is up by 20% over the last week "and will sadly rise further," the PM warned.
ITV News Political Editor Robert Peston reacts to the latest lockdown:
The surging number of cases is down to a new variant of the Covid - which is 50% to 70% more transmissible - and was spreading in a "frustrating and alarming" manner, Mr Johnson said.
While the Covid-19 alert level is to be moved to five – the highest setting – the UK’s chief medical officers have recommended.
He added: "I know how tough this is, and I know how frustrated you are and I know you have had more than enough of government guidance about defeating this virus, but now, more than ever, we must pull together."
Mr Johnson said that the weeks ahead would be the "hardest yet" but added that he believed the country was entering "the last phase of the struggle".
'Stay at home' order returns:
Like the first lockdown in March, the stay at home order will return with limited exceptions including essential shopping, fleeing violence, care giving, and medical appointments.
Mr Johnson said: "You may only leave home for limited reasons permitted in law, such as to shop for essentials, to work if you absolutely cannot work from home, to exercise, to seek medical assistance such as getting a Covid test, or to escape domestic abuse."
Workers will once again be expected to work from home unless they are unable to do so, for example those working in construction workers or key workers.
Exercise outside the home is permitted, but the government has urged this is done ideally just once a day and that people stay local to their home.
People can only meet with one other person from outside their household if it is for exercise purposes.
As in March, police will have legal power to enforce the rules - including the threat of fines and dispersal orders.
School set to close:
In a U-turn on the government's plan for a staggered reopening of schools and colleges with mass testing, schools will not open and online learning will return for the majority.
Schools and colleges will be closed except for key worker children and vulnerable children while nurseries, special school and alternative provision can remain open.
On why the decision was not made sooner - amid rising pressure from unions in recent weeks - Mr Johnson said: "The answer is simply that we’ve been doing everything in our power to keep schools open because we know how important each day in education is to children’s life chances".
BTEC exams scheduled to happen in the next few days will continue as planned, but the future of this year's GCSE and A Level exams remains unclear.
In his address, Mr Johnson warned it would "not be possible or fair for all exams to go ahead as planned this summer".
The PM said the Education Secretary, Gavin Williamson, will work with exam regulator Ofqual to put in place alternative arrangements.
The rules around childcare support bubbles will stay as they are.
University students will be expected to stay at home and not return to campus until at least the middle of February.