The prime minister acted “decisively” on the lockdown in England “in the face of new information”, Rishi Sunak says.
People must now stay at home except for a handful of permitted reasons and schools have closed to most pupils.
The chancellor said the action was “regrettable” but it was “right we take these measures”, which will be reviewed on 15 February, to suppress the virus.
It came after UK chief medical officers recommended the Covid threat level be increased to five – its highest level.
The prime minister said vaccinating the top four priority groups by mid-February could allow restrictions to be eased.
Tough new lockdown restrictions forbidding people from leaving home for non-essential reasons
have also come into force across the Scottish mainland – these rules will be reviewed later this month.
In Wales, which has been in a national lockdown since 20 December, schools and colleges will stay shut until 18 January for most pupils.
Northern Ireland, which entered a six-week lockdown on 26 December plans to put its stay-at-home message into law, and will have an “extended period of remote learning”, the Stormont Executive said.
The UK reported a record 58,784 cases on Monday, as well as a further 407 deaths within 28 days of a positive test.
Meanwhile, Prime Minister Boris Johnson is due to hold a press conference in Downing Street at 17:00 GMT with chief medical officer for England Prof Chris Whitty and the government’s chief scientific adviser, Sir Patrick Vallance.
Elsewhere, Mr Sunak has announced that businesses in the retail, hospitality and leisure sectors are to be given a one-off grant worth up to £9,000, with the measure costing £4bn across the UK.
Cabinet Office Minister Michael Gove confirmed GCSE and A-Level exams in England were being cancelled this year, saying Education Secretary Gavin Williamson will make a statement in the House of Commons on Wednesday on “how we want to make sure children are fairly assessed”.
Mr Gove told BBC Breakfast: “It is a very, very difficult time for the whole country, that’s why it’s so important we do everything we can in government to vaccinate people.
“The more we vaccinate the easier it will be to lift these restrictions.”
He said a million people had been vaccinated so far “up until the weekend” and it is hoped that number will reach more than 13 million in February.
When asked about the target of two million vaccines a week and concerns over logistics and the safety systems, he said: “We do want to make sure these vaccines are delivered in the safest possible way that we do not waste a drop.
“The process of making sure that the vaccines can be placed in the appropriate vials and then safely injected into people’s arms is a complicated exercise, but the NHS has more than risen to the challenge.”
Mr Gove said the lockdown was “not easy” for anyone, but “I hope the instructions are clear”.
The government was “looking at further options” to restrict international travel, he said.
Mr Gove told Sky News he could not say exactly when the lockdown in England would end, adding: “I think it is right to say that as we enter March we should be able to lift some of these restrictions but not necessarily all.”
Prof Andrew Hayward – a member of the government’s Scientific Advisory Group for Emergencies (Sage) – told BBC Radio 4’s Today programme the lockdown measures “will save tens of thousands of lives”.
But he said “the virus is different” and “it may be that the lockdown measures that we have are not enough”
“This lockdown period we need to do more than just stay at home, wait for the vaccine, we need to be actively bearing down on it,” he said.
By 8pm on Monday it felt inevitable.
But it doesn’t mean that a national instruction to close the doors was automatic. Or indeed that new lockdowns in England and Scotland aren’t still dramatic and painful.
With tightening up in Wales and Northern Ireland too, the spread of coronavirus this winter has been faster than governments’ attempts to keep up with it – leaving leaders with little choice but to take more of our choices away.
There is much that’s an echo of March. Work, school, life outside the home will be constrained in so many ways, with terrible and expensive side-effects for the economy.
This time, it’s already spluttering – restrictions being turned on and off for months have starved so much trade of vital business.
But there’s a lot that’s different too. After so long, the public is less forgiving of the actions taken, and there is frustration particularly over last-minute changes for schools; fatigue too with having to live under such limits.
Announcing England’s lockdown on Monday, Mr Johnson said hospitals were under “more pressure from Covid than at any time since the start of the pandemic”.
He ordered people to stay indoors other than for limited exceptions – such as essential medical needs, food shopping, exercise and work that cannot be done at home – and said schools and colleges should move to remote teaching for the majority of students until at least half term.
And the prime minister said all care home residents and their carers, everyone aged 70 and over, all frontline health and social care workers, and the clinically extremely vulnerable will be offered one dose of a vaccine by mid-February.
While the rules become law in the early hours of Wednesday, people should follow them now, Mr Johnson added.
Under England’s new measures, support and childcare bubbles will continue, and people can meet one person from another household for outdoor exercise.
Exercise should be limited to once per day.
Communal worship and funerals can continue, subject to limits on attendance. Weddings are allowed in “exceptional circumstances” with up to six people.
Mr Johnson said the new variant of coronavirus, which is up to 70% more transmissible, was spreading in a “frustrating and alarming” manner and warned that the number of Covid-19 patients in English hospitals is 40% higher than the first peak.
People who are clinically extremely vulnerable will be contacted by letter and should now shield once more, Mr Johnson said.
The House of Commons has been recalled to allow MPs to vote on England’s new restrictions on Wednesday.
Labour leader Sir Keir Starmer said his MPs would “support the package of measures”, saying “we’ve all got to pull together now to make this work”.
Earlier on Monday, First Minister Nicola Sturgeon issued a stay-at-home order for Scotland, beginning at midnight and lasting until the end of January.
Scotland’s lockdown, which is for the mainland and Skye, will also see schools closed to pupils, places of worship closed and group exercise banned.
“It is no exaggeration to say that I am more concerned about the situation we face now than I have been at any time since March last year,” Ms Sturgeon said.
At-a-glance: New rules
- People cannot leave their homes except for certain reasons, like the first lockdown last March
- These include essential medical needs, food shopping, exercise and work for those who cannot do so from home
- All schools and colleges will close to most pupils from Tuesday with remote learning until February half term
- Early years settings such as nurseries will stay open
- End-of-year exams will not take place this summer as normal
- Elsewhere, university students should not return to campuses and will be taught online
- Restaurants can continue to offer food delivery, but takeaway alcohol will be banned
- Outdoor sports venues – such as golf courses, tennis courts and outside gyms – must close
- But outdoor playgrounds will remain open
- Amateur team sports are not allowed, but elite sport such as Premier League football can continue
In mainland Scotland and Skye:
- Nursery, primary and secondary schools will close to all most pupils until February. Learning will move online
- People should only leave home for essential reasons, like the first lockdown last March
- Those who are shielding should not go into work, even if they cannot work from home
- A maximum of two people from up to two households can meet outdoors, excluding under-12s who can play together outside
- Places of worship will close except for weddings (up to five people) and funeral services (up to 20 people). Wakes are not allowed
- The definition of an essential business will be tightened with premises such as ski centres, large retail showrooms, and cosmetic clinics required to close
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