Masks are being recommended in England’s schools before their compulsory return to shops and public transport as a third case of the Omicron variant of coronavirus was detected in the UK.

A further escalation of measures to combat the spread of the concerning new strain of coronavirus was announced when staff and pupils in Year 7 and above were “strongly advised” to cover their faces in communal areas outside classrooms from Monday.

Face coverings will be mandatory on public transport and in shops and other settings including banks, post offices and hairdressers from Tuesday morning, when isolation rules will return for international arrivals until they receive a negative PCR test for Covid-19.

Close contacts of positive Omicron cases were being ordered to isolate for 10 days even if they have been vaccinated, amid concerns the variant first detected in South Africa could spread rapidly and partially evade existing jabs.

News Shopper: The latest cases visited London (PA)The latest cases visited London (PA)

A third case of the “variant of concern” was detected by the UK Health Security Agency (UKHSA) on Sunday, this time of a person who visited Westminster in London before leaving the country. The first two were identified in Nottingham and Essex.

Despite the reintroduction of rules, Health Secretary Sajid Javid told families they should plan for a great Christmas “as normal” and insisted it was “nowhere near” time to reintroduce social distancing rules and work-from-home guidance.

Dr Jenny Harries, chief executive of the UKHSA, acknowledged it was “very likely” that further cases of Omicron would be discovered in the coming days.

Labour has called for enhanced measures at the border.

A new testing regime is being introduced under the emergency measures announced over the weekend to slow the spread of the new Omicron variant following its detection by Government scientists.

Education Secretary Nadhim Zahawi recommended that staff, visitors and pupils in Year 7 and above should wear masks in communal areas in schools, colleges and universities such as corridors, canteens and halls in England from Monday.

Though the reintroduction of masks in England in shops will bring the nation back closer into line with Scotland, Wales and Northern Ireland, they are not being required in pubs and restaurants.

Mr Javid said it “would be irresponsible to make guarantees” during the ever-changing pandemic, but he told Sky’s Trevor Phillips on Sunday: “I think people should continue with their plans as normal for Christmas, I think it’s going to be a great Christmas.”

With the Government stopping short of introducing its plan B to tackle Covid-19 this winter, Mr Javid played down any need to reintroduce social distancing rules or work-from-home guidance.

“We know now those types of measures do carry a very heavy price, both economically, socially, in terms of non-Covid health outcomes such as impact on mental health,” he told Sky.

“So, if one was to make decisions like that they would have to be done very, very carefully and we’re not there yet, we’re nowhere near that.”

Mr Javid said he expected to receive new advice “imminently”, within the next couple of days, from the Joint Committee on Vaccination and Immunisation (JCVI) after it was tasked with reviewing whether boosters should be extended to everyone over 18.

The group will also consider whether second doses should be offered to 12- to 15-year-olds, and whether the waiting time before a booster jab could be reduced.

Professor Anthony Harnden, the JCVI’s deputy chairman, told BBC Radio 4’s Broadcasting House that extending the age range for boosters and reducing the delay before receiving them was “a sensible strategy”, and told people under 40 to expect third jabs to be offered to them “earlier than we had previously envisaged”.

Passengers arriving in the UK from 4am on Tuesday will be required to take a PCR test by the end of their second day from entry and isolate until they receive a negative test, while 10 southern African nations have been added to the red list.

Mr Javid admitted that passengers flying in from southern Africa before 10 nations were added to the red list were not tested on landing and they could have taken public transport to get home.

“I think the speed at which we acted could not have been any faster,” he told The Andrew Marr Show on the BBC, adding that those arrivals had been contacted and told to take tests.

As officials tried to trace potential contacts of the Omicron case in Essex, the local authority urged visitors to a KFC in Brentwood on November 19 to get drive-through tests, raising questions about how long ago the variant may have arrived in the UK.

The individual in Essex was said to have been in contact with the Nottingham case, who is understood to be linked to travel to southern Africa, but officials have declined to say when that travel took place.

Yvette Cooper, the Labour MP who chairs the Commons Home Affairs Committee, urged the Government to immediately reinstate pre-travel tests because the new approach “leaves far too many gaps”, with potentially infected passengers able to travel home on public transport.

Prime Minister Boris Johnson announced the bulk of the “temporary and precautionary” measures on Saturday, pledging that they would be reviewed in three weeks.

Mr Javid told Times Radio it was planned for the new regulations to be laid in Parliament on Monday, with MPs expected to be given a vote within 28 days and after they come into force.

A number of backbench Tories may stage a rebellion, but it is thought unlikely Labour will oppose the restrictions, virtually guaranteeing that they will pass.

Britain will convene an urgent meeting of G7 health ministers on Monday to discuss Omicron.

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