Prime Minister Boris Johnson is to lead a Downing Street news conference at 17:00 GMT today.

He will be joined by England's chief medical officer, Prof Sir Chris Whitty, and chief scientific officer Sir Patrick Vallance.

We'll bring you live updates of what they have to say right here.

While the NHS has seen a significant increase in admissions, it is "pleasing" the number of patients requiring ventilation support has not increased to the same extent, No 10 says.

The prime minister's official spokesman says the government keeps "an extremely close eye on NHS capacity at all times".

Asked whether the number of people in intensive care is playing an "important role in the prime minister's thinking" on how to handle the Omicron spike, the Downing Street spokesman says: "It is one aspect that informs how the NHS is dealing with this current wave."

He adds that the booster programme and "evidence that Omicron may be milder" meant "we are not seeing those huge waves in cases translate into those needing the most serious care that we saw perhaps in previous waves, but that still puts the NHS under significant pressure".

Downing Street is once again saying it does not "see any data to suggest that further restrictions would be the right approach" to tackle Covid in England.

The prime minister's official spokesman says that while the public should be in "no doubt" that it will be a "difficult" time for the NHS, there are "significant mitigations in place for our NHS to help them through what is going to be a very challenging winter".

He also confirms that all government departments have been asked to look at how they would mitigate against as much as a quarter of their workforce being absent.

He says that in some circumstances that would involve a military aid request but that would not apply in all circumstances and there was no blanket requirement for military assistance.

On testing, the government is massively increasing capacity for both PCR and lateral flow tests, the spokesman says.

"We're doing, I think, roughly around 1.5 million tests across the system each day, which, as I say, is the largest in the world, so there is testing capacity available for those who need it, but we will keep that under review, depending on how prevalence tracks over the coming weeks," he says.

Image source, Getty Images

France's most famous twins, known for hosting a TV science show in the 1980s, have died of coronavirus within days of each other in hospital.

Grichka Bogdanoff died on 28 December, while his brother Igor passed away on Monday.

Aged 72, the brothers had not been vaccinated against Covid.

Their friends said they were convinced their healthy lifestyle would protect them and they were admitted to hospital in mid-December.

Although their families did not specify the cause of their deaths, their lawyer Edouard de Lamaze confirmed they had both contracted the virus.

Family friend Pierre-Jean Chalençon said they had left it too late to seek hospital treatment, deciding it was similar to flu.

"People have said they were anti-vaxxers, but they absolutely weren't," he told BFMTV.

"Several friends told them to get themselves vaccinated, but they felt because of their lifestyle and their [lack of] comorbidity, they weren't at risk of Covid."

Read more here.

We've been hearing from Sir Keir Starmer, who's been making a speech in Birmingham.

The Labour leader said a lack of "sufficient" Covid tests nearly two years into the pandemic was "simply unacceptable".

"Omicron was a word we hadn't heard several weeks ago but the idea that there would be a variant that would get around some of the protections in place was a known threat six months ago," he said.

Asked if a Labour government would reduce Covid isolation to five days, as has been done in the US, Sir Keir said his party has "always taken the approach of following the science", and would continue to do so.

He also said Labour would come to an "appropriate judgement call" on whether to offer a fourth vaccine dose when it had studied all the evidence.

Stephen McDonell
BBC News, China correspondent

Image source, Getty Images

With only a month to go until the opening ceremony of the Winter Olympics, Beijing is taking major steps to restrict access to the Games site as it prepares to welcome athletes from countries where the Omicron variant is spreading wildly.

The Taizicheng high-speed train station, in the mountains outside Beijing, is now closed to the public. Only special trains carrying those with Olympic clearance will arrive.

After vaccinated athletes enter the Chinese capital, they'll go straight into a dedicated sporting bubble which includes transport links, as well as hotels and other venues.

With bubble walls already going up, some local residents are having to choose whether to be closed off from the rest of China for the duration of the Games or whether to leave their homes for two months.

Officials in Beijing are implementing strict separation policies as they prepare for the likelihood that international teams could bring the Omicron variant into a country still pursuing a zero-Covid strategy.

Image source, PA Media

Labour leader Sir Keir Starmer has said the country needs "better leadership from the government" when it comes to the pandemic.

In a speech delivered in Birmingham this morning, he said: "If we're to keep our schools open, and we must, what we need is many more of our school children vaccinated."

He said the government should have used the Christmas break to vaccinate children - with only about half of eligible over-12s having been - and said his party had been calling for better ventilation in schools for about a year.

"The government has now come up with, I think, something like 7,000 ventilators, which is about one in four for all the schools that need it."

Over the weekend the government reintroduced the wearing of masks in secondary school classrooms in England, to go alongside additional air cleaning units.

Sir Keir added that the government was right to say secondary school pupils should test twice a week but it was "nowhere near achieving that".

Hazel Shearing
Education correspondent

Pupils in England have been taking lateral flow tests before heading into their lessons this morning.

At one school in Stoke-on-Trent, Staffordshire, testing stations were set up in the main hall. Here's how it worked:

1. Children were given a registration card on arrival to take to a testing table, where they were then handed a swab and asked to carry out their lateral flow test.
2. They were then sent to a waiting room while their tests results were processed.
3. If the results were negative after 15 minutes, they could go to class. But if not, they were sent home.

One pupil who had arrived early to take her test told BBC Breakfast: "I’m glad to be back in school and to be learning again."

Another, who had mock exams on the horizon, said he was "pretty nervous".

"I’ve missed quite a big chunk of learning, but I’m sure I'll do fine."

Across the UK, staff and secondary pupils are being urged to test themselves regularly, and schools have been asked to ensure there is good hygiene and ventilation.

Image source, PA Media

We've been bringing you reports of widespread staff shortages due to people having to self-isolate - with the transport industry and the NHS among the worst hit.

Boris Johnson has tasked ministers to come up with "robust contingency plans" for staff absences.

The Cabinet Office has said public sector leaders have been asked to prepare for "worst case scenarios" of 10%, 20% and 25% absence rates.

Steve Barclay - the Cabinet Office minister - is chairing regular meetings with ministers to assess how the spread of the Omicron variant is affecting workforces and supply chains.

And Johnson has asked ministers working with their respective sectors to test preparations and contingency plans to limit disruption, the Cabinet Office added.

More on this story here.

Robin Brant
BBC News, Beijing

Image source, Reuters

Covid first appeared in China, and up until a few weeks ago, the government had managed to contain it to such a level that new cases were negligible and mainly coming from people arriving from abroad.

What Beijing calls its "dynamic zero Covid" strategy combines mass vaccination with a regime of constant testing, nationwide monitoring of people's movements, temperature-taking and phone apps to prove you don't pose a threat.

All of that amounts to a hyper vigilance about any new outbreak. If and when one is spotted, the reaction is severe.

China has been wedded to this approach since the beginning because it's likely the leaders from Xi Jinping down consider anything less would cause illness and death on a scale that would be politically, economically and socially unacceptable.

The ruling Communist Party took much of the credit for containing the virus early on - after it had spread beyond China's borders - and diverting from that would undermine its credibility.

There is a broad acceptance of that, and the stringent restrictions it can bring among many Chinese who for decades have not felt they can rely much on the public health system.

So illness and the prospect of losing your job, let alone your life, is existentially daunting.

Add to that the prestige attached to - safely - hosting another Olympic Games in a few weeks' time and the fast approaching Chinese new year mass migration of millions across this country, and it’s clear there is little doubt that the government will remain committed to "zero Covid" for the forseeable future.

Image source, Reuters

This morning we have been hearing from the government's vaccines minister Maggie Throup who, when asked by Sky News how many hospitals had declared critical incidents, said she didn't want to give a number because it was a fast-moving situation.

She also did not give an exact figure when asked by the BBC how many ex-teachers had returned to the profession to help with staff shortages, saying it was in the thousands.

The Liberal Democrats' health spokesperson Daisy Cooper has criticised Throup, saying: "If ever proof was needed that the government is asleep at the wheel with this staff shortage crisis, the vaccine minister's non-answers this morning just about sum it up.

"Our hospitals are at breaking point and schools are spread thin, yet hapless ministers haven't got a clue about the true extent of the problems in these settings."​

Image source, Getty Images

With many children heading back to class, Northern Ireland's education minister says it's important to keep schools open amid rising Covid cases.

"Our priority and my priority remains keeping our children in school," Michelle McIlveen told the BBC's Good Morning Ulster.

Headteachers and teaching unions have been asking for greater support and clarity over issues like staff absences.

The education minister says she will "absolutely" support headteachers - but guidance to schools hasn't changed, meaning they should continue with similar Covid mitigations they had before the break.

One headteacher, Maire Thompson, says five of her staff phoned in sick on Tuesday, and it was going to be "a tricky time ahead".

Thompson has also called for air filters to be used in schools in Northern Ireland, following news that these were being distributed in England.

A health boss has said Lancashire is braced for a "tsunami" of Omicron cases as a critical incident is declared.

Morecambe Bay NHS Trust declared the incident on Monday evening as Covid hospital admissions continue to rise and more staff test positive for coronavirus.

Speaking to BBC Radio 4's Today programme, Dr Sakthi Karunanithi, public health director for Lancashire County Council, says the county ias at "the foothills" of an Omicron wave.

"Lancashire is beginning to experience what London did at the beginning of last month and, of course, London is better resourced and the infrastructures are well organised compared to other regions, so we are bracing ourselves for a tsunami of Omicron cases in Lancashire."

He says they have seen a shift from 20 to 40-year-olds being affected to the over-60s - and there are concerns around staff absences in the NHS and in schools.

At least five other NHS trusts in England are known to have declared critical incidents in the past week - as the health service deals with staff shortages caused by the surge in Covid cases.

Hazel Shearing
Education correspondent

As pupils return to classrooms, the head of one education trust has told the BBC he's concerned about staffing shortages as Covid cases surge.

Tom Quinn, chief executive of the Frank Field Education Trust, says it used up its yearly fund for supply teachers last term.

“The call-to-arms to have extra funding could help us but… we can’t find supply teachers to come in,” he told BBC Breakfast at an academy in Stoke-on-Trent, Staffordshire.

“We need high quality professional teachers to come in to help children learn and they’re not there.”

Before term ended, the education secretary appealed to former teachers to come out of retirement and sign up with teacher supply agencies to help cover staff absence. There has been a similar call to retired staff in Northern Ireland.

However, supply agencies warned they were unlikely to be in place at the start of this term.

World number one Novak Djokovic says he will defend his Australian Open title later this month after receiving a medical exemption from having a Covid-19 vaccination.

All players and staff at the tennis tournament must be vaccinated or have an exemption granted by an expert independent panel.

Djokovic, a nine-time Australian Open winner, has not spoken publicly about his vaccination status.

The tournament begins in Melbourne on 17 January.

"I've spent fantastic quality time with my loved ones over the break and today I'm heading down under with an exemption permission," he said on Instagram on Tuesday. "Let's go 2022."

Read more here.

Image source, Reuters

One of the top questions being searched on Google in the UK this morning is "if a parent tests positive for Covid can the child go to school?"

Advice on the government's website, external says anyone below the age of 18 years and six months is "not legally required to self-isolate" even if they live in the same household as someone who has Covid. So the answer for most pupils whose parent tests positive is that, if they don't have symptoms themselves, they would be able to go to school.

The guidance "strongly advises" anyone over five years old, who is living in the same household as the infected person, takes a daily lateral flow test. This should be done "every day for seven days, or until 10 days after the household member who has Covid-19 started their self-isolation period if this is earlier."

Official guidance says lateral flow tests should be taken before leaving home for the first time that day. If the test result is positive the government says you should then self-isolate.

Read more government guidance for households here, external. And you can read more about schools during the pandemic here.

Robin Brant
BBC News, Beijing

We were reporting earlier about the city of Xian which is under lockdown and where residents are being forced to barter for supplies - now another city in China has gone in to a full lockdown in the latest effort to stop a new wave of Covid infections.

Authorities have told people in Yuzhou to stay in their homes.

Almost all vehicles have been banned from the roads. All shops and businesses - apart from supermarkets supplying food - have been told to close.

The measures have been imposed after three asymptomatic cases were discovered.

Yuzhou is a small city by Chinese standards, with a population of about 1.2 million.

China's authorities say these latest cases are of the Delta variant. So far there have been only two reported cases of Omicron in the Chinese mainland.

Image source, Getty Images

Prof Russell Viner, an expert in child and adolescent health at UCL, says vaccinating teenagers has been a harder message to sell to the public, and some people may have been left confused.

"We haven't covered ourselves with glory on vaccinating our 12 to 15-year-olds, but I think there's very good reasons for that," he tells BBC Radio 4's Today programme. According to data from late December, less than half of 12 to 15-year-olds in England had had a first dose.

"The vaccination for adults is quite a different proposition, that's about protecting yourselves. We vaccinate teenagers largely... a little bit to protect them, but largely to reduce disruption to education and protect the broader population," he says.

"That's a much more difficult message to sell and there've been concerns about myocarditis, which means that our messaging has changed over time.

"That has to some extent confused the population, but I think the UK's been really quite honest about the risks and the benefits of vaccinating teenagers in a way that perhaps has not driven the message home to our young people and their families in the way it could, but I think we have been honest."

All children aged 12 and over are now being offered two doses.

The Omicron variant is driving huge numbers of infections - but fewer people with coronavirus are ending up in hospital than a year ago.

But the vast number of infections means even though the variant seems to be causing milder illness, the number of patients in hospital with Covid has been going up recently.

A hospital case this winter is not the same as one from earlier in the pandemic - and for one thing, a growing proportion of patients are being treated for something else and just happen to have the virus.

The good news is early reports suggest patients are not spending as long in hospital and the numbers needing critical care have hardly changed.

Read more here about what's going on from our correspondent Nick Triggle.

The talk in many developed countries is of how many boosters will be necessary in the future to protect their population - but a senior epidemiologist for the World Health Organisation warns those countries cannot boost their way out of the coronavirus pandemic.

Maria van Kerkhove tells the BBC a global crisis demands vaccination on a global scale.

While many wealthy nations are offering booster shots to their populations as Omicron cases rise, in the lowest-income countries only 3% of people are fully vaccinated.

Dr Van Kerkhove describes this as a moral and ethical failure, saying the supply of vaccines to poorer nations must be vastly increased to meet the WHO goal of vaccinating 70% of the world's population by July 2022.

She also warns that, with new variants constantly emerging, relying on boosters is not enough.

Global vaccination must be accompanied by driving down transmission through simple, effective public health tools - such as wearing face masks, social distancing and ventilation in public spaces.