Prof Van-Tam says "it's not all bad news from my corner of the room" with the authorisation of the Oxford-AstraZeneca vaccine.

He goes on: "I want to caution everybody, particularly the media, about over-forensic examination of percentage vaccine effectiveness.

"It's really important to remember that the definition of illness in the Pfizer and AstraZeneca programmes were different, so they were slightly different end-points, so you can't really compare them.

"But what really matters to us is not an end-point that measures illness, but how these vaccines are going to impact on severe disease, on hospitalisations and on deaths.

"I'm confident... that both of these vaccines will do that."

Prof Van-Tam says it is "a pretty grim and depressing picture at the moment”, with the majority of the population living under the toughest restrictions.

The situation in the UK is “precarious” in many parts of the country, particularly in the South East and London, he says.

And he adds that the NHS has almost certainly not yet seen the impact of infections from people mixing over Christmas.

Image source, HM Government

Prof Stephen Powis, NHS England's national medical director, reiterates that "it will continue to be tough over the next few weeks."

But he adds: "Everybody is able to help the NHS and assist our incredible staff and play their own parts.

"We know it's the end of the year... but it's absolutely vital that this year everybody continues to follow the guidance by staying at home and not mixing," he says.

"Stay at home, mark the new year with just nearest and dearest within the rules. Covid loves a crowd, so please leave the parties for later in the year."

Prof Van-Tam says the percentage of people testing positive for the new variant is increasing at a "very substantial rate” in some areas including the east and south of England.

In other areas, he says an uptick of the new variant is also beginning to occur, which is of “enormous concern”.

Image source, HM Government

Chris Mason
Political Correspondent

While many of us will be heartily glad to wave good riddance to 2020, as we've long known - and the prime minister has just spelt out - 2021, or at the very least the early months of it, are going to be fraught with anxiety, disruption and the disease.

Parents have been desperately waiting for news about schools in England - just days before the start of the Spring term - a list of affected local authority areas is about to appear on the government's website.

Social distancing, the cancellation of so much of what we normally take for granted, including New Year's Eve celebrations, rolls on into January.

"Covid loves a crowd, so please leave the parties for later in the year," Professor Powis of the NHS has just told us.

Prof Jonathan Van-Tam, deputy chief medical officer for England, has been talking us through the latest data.

He says the average rate of infections has doubled to 380 per 100,000 over the past two weeks.

He says there has been "considerable growth" across the country, but particularly in London, the South East, the home counties and south Wales.

This is also being reflected in the number of people going into hospital with Covid-19, with “very sharp rises" in London, the South-East and east of England, he adds.

Referring to the new tier measures announced a little earlier by Health Secretary Matt Hancock, the prime minister says: "At this critical moment, with the prospect of freedom within reach, we've got to redouble our efforts to contain the virus.

"No-one regrets these measures more bitterly than I do, but we must take firm action now."

"I must ask you to follow the rules where you live tomorrow night and see in the new year safely at home," the prime minister tells the public.

"That means not meeting up with friends or family indoors, unless they're in the same household or support bubble, and avoiding large gatherings of any kind."

He adds: "We are still in the tunnel of this pandemic."

Boris Johnson says the approval of the Oxford-AstraZeneca vaccine is a "fantastic achievement for British science" which will allow the UK to vaccinate more people more quickly.

Guidance that the first dose of the vaccine can help protect people against the worst effects of the virus means more vulnerable people can be vaccinated as quickly as possible, he says.

To minimise disruption in schools the government is "massively expanding" its testing operation, the prime minister says.

Every secondary school pupil will be tested as they return "and regularly thereafter".

The prime minister says the "sheer pace" of the spread of the new variant "requires us now to take even tougher action in some areas."

In most of England, primary schools will still reassemble next week, as planned, he says.

But in some areas with higher infections, the start of the new term will be delayed until at least 18 January, when latest data will be reviewed.

In secondary schools, all vulnerable children and children of critical workers will go back next week as originally planned. But exam year pupils in secondary schools will learn remotely during the first week of term. The remaining secondary school pupils will go back a week later.

Prime Minister Boris Johnson is now beginning today's Downing Street press conference. We'll bring you all the latest here.

Chris Mason
Political Correspondent

Once upon a time, the period between Christmas and New Year was a little lean on the news front.

Not so 2020. But then again, 2020 has consistently gone its own way.

A mere hours before the prime minister took centre stage in the Commons on a big day for Brexit, he's back again on our screens and speakers with a Coronavirus-related news conference - alongside Professor Jonathan Van-Tam, one of England's deputy chief medical officers, and Stephen Powis, the NHS's medical director for England.

Nick Triggle
Health Correspondent

Image source, Getty Images

It is a bittersweet day.

News of approval for a second Covid vaccine has been followed by the announcement that more of England is to enter tier four.

That means, with the exception of a few pockets, the whole of the UK is pretty much in lockdown.

The fear now is that this will become the status quo for weeks.

Hospitals are clearly struggling with close to 24,000 patients in hospital with Covid – that’s around one in five beds.

Until those numbers start coming down, the restrictions are likely to stay in place.

The jury is still out on how significant the impact of these restrictions will be on the new faster-spreading variant.

If the effect is limited, it is likely to be late February before we can expect the rollout of the vaccines to have a significant impact on the numbers falling seriously ill.

Phil Mackie
Midlands correspondent, BBC News

Image source, Getty Images

It was the news nobody wanted but everybody expected.

Britain’s second city and most of the rest of the Midlands will wake up tomorrow morning facing the strictest restrictions in tier four.

Infection rates are not as high as they are in London and the South East but they have continued their inexorable rise.

Lisa McNally, the director of public health for neighbouring Sandwell, tweeted that positive cases had gone up 21% in seven days in Birmingham and the Black Country.

The University Hospitals Birmingham Trust has more than 500 Covid patients in its four hospitals, nearly 100 more than a week ago. At the peak of the first wave it was treating more than 700, but Andy Street, the Conservative mayor of the West Midlands, told me that now was the time to act, because tier three was “no longer working”.

The city centre was busier today than it has been for some time as people took their last chance for some retail therapy in non-essential shops.

There was an air of resignation as everything began to close. One teenager told me she was sad.

“I’ve just turned 18, and I haven’t been able to do any of things you’re supposed to be able to do at 18,” she said.

Responding to Gavin Williamson's statement, Labour's shadow education secretary Kate Green says the delay and disruption to the start of the school term "is a direct result of government failures".

While the cost to pupils caused by school closures are huge, she says action must be taken to control the virus.

However, she says the government has failed to give schools the support they need, including to roll out mass testing.

"We should never have been in the position we are in today," she says, adding that if the government had acted quicker and given schools the support they need throughout the pandemic, they wouldn't be facing disruption in the new year.

In response, Williamson says the government has provided extra support to schools to set up mass testing, including equipment and funding.

He also adds that assessments for technical and vocational qualifications in early January will continue as planned.

You can read more on Gavin Williamson's announcement here.

Conservative MP Robert Halfon asks the education secretary what risk assessment the government has made on the impact of closing schools on educational inequality, wellbeing and mental health.

Gavin Williamson says "we know how important it is - children need to be in school".

"That is why we'll always do everything we can do to resist knee-jerk reactions to close schools or colleges because we recognise how important it is for children's life chances for them to be in school."

He adds that the government has commissioned a study on the impact of lost learning on pupils, especially those in exam years, to inform its decisions in future.

Conservative MP James Cartlidge asks the education secretary whether he agrees that vaccinating teachers as soon as possible would make schools safer and reduce pressure to close them.

In response, Gavin Williamson says: "The decision in terms of vaccination has to be prioritised across a whole raft of areas, but the key thing is those people who are most clinically vulnerable.

"But as we get through that stage of clinical need, I would certainly hope that we would be able to look at how we can use vaccinations for those who are in the teaching profession and who support education."