Health Secretary Sajid Javid has said mandatory mask-wearing will return to shops and public transport on Tuesday, as he told families to plan for Christmas “as normal” despite new rules to combat the Omicron coronavirus variant.

He said on Sunday it was “nowhere near” time to reintroduce social distancing rules and work-from-home guidance, despite a raft of precautionary measures being reintroduced to tackle the concerning strain of Covid-19.

Passengers arriving in the UK have been told that from Tuesday morning they will have to take a PCR test for Covid-19, with the expectation they will have to self-isolate until they test negative.

All contacts with a suspected case of Omicron will have to isolate for 10 days, regardless of their vaccination status, amid concerns that existing jabs will be less effective against the strain, which is believed to spread rapidly.

Details of the plans were incomplete when announced by Boris Johnson after two cases of the variant were confirmed in England on Saturday, but Mr Javid said the “face-mask rules are planned to come in on Tuesday” to bring the nation back closer into line with Scotland, Wales and Northern Ireland.

He said it “would be irresponsible to make guarantees” during the ever-changing pandemic, but 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 downplayed there being a 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 expects 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 all over-18s.

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.

“I’ve also asked the NHS to prepare for much greater capacity in our vaccination programme,” Mr Javid told The Andrew Marr Show on the BBC.

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 under-40s to expect third jabs to be offered to them “earlier than we had previously envisaged”.

Mr Javid said the testing regime for international arrivals will be introduced “as soon as possible”, despite online passenger locator forms stating PCR tests will be required rather than lateral flow tests from 4am on Tuesday.

Scotland, Wales and Northern Ireland said they intend to mirror the border restrictions.

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

“I think the speed at which we acted at could not have been any faster,” he said, adding those arrivals before the change had been contacted and told to take tests.

Cardiff Rugby has said the team is unable to leave South Africa following two positive cases of Covid-19, one of which is suspected to be the Omicron variant.

In a statement, the club said its players had returned to their hotel to isolate having been booked on to a flight set to depart on Sunday afternoon and it is now working with authorities to ensure the party’s safe passage home when appropriate.

A spokesperson said: “Everybody concerned in this highly challenging situation would like to thank their families, friends, colleagues and the wider rugby family for their many messages of concern and well wishes.”

Professor Neil Ferguson, the Scientific Advisory Group for Emergencies (Sage) member whose modelling helped instigate the first lockdown, said he expects to see “substantially larger numbers” of Omicron in the UK in the coming days but welcomed the new measures as “proportionate” to slow the spread while scientists analyse its properties.

“That’s not to say we can be complacent, if we do see very rapid growth of Omicron – and that’s a big if at the moment, and we have no guarantee we will – but if we do then, undoubtedly, I think the Government would be wise to keep all options on the table in terms of how to respond to that,” He told BBC Radio 4’s The World This Weekend programme.

Yvette Cooper, the Labour MP who chairs the Commons Home Affairs Committee, called for 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.

Mick Lynch, the general secretary of the Rail, Maritime and Transport union, called for additional resources to police “angry passengers who refuse to comply” with the reintroduction of masks.

During an emergency Downing Street press conference on Saturday, the Prime Minister announced the “temporary and precautionary” measures were needed after two cases of the new variant first discovered in South Africa were detected in Nottingham and Brentwood, Essex.

The individuals and their households were ordered into self-isolation and targeted testing is being carried out in areas where they are thought to have been infectious.

Mr Johnson said the measures will be reviewed in three weeks as he warned Omicron appears to spread “very rapidly”, can transmit between the double-vaccinated and may partially reduce the protection of existing vaccines.

He stopped short of announcing his Plan B to tackle Covid-19 this winter, which includes mandatory use of vaccine certificates in certain venues and reinstating work-from-home guidance.

Government advisers on Sage said during a meeting on October 14 that home working is likely to have the greatest individual impact on transmission out of the measures in Plan B, which they said would have the greatest impact if introduced in unison.

To further slow the arrival of cases, ministers said Malawi, Mozambique, Zambia and Angola will face travel restrictions from Sunday, when they will join South Africa and five other neighbouring nations on UK red lists.

Mr Javid told Times Radio it is planned that the new regulations will 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 would oppose the restrictions, virtually guaranteeing that they will pass.

The UK, Germany and Italy all confirmed the presence of Omicron on Saturday after the variant first detected in South Africa was reported to be in Belgium a day earlier.

Experts hope existing vaccines will still be good at reducing serious disease from Omicron, but manufacturers are looking at tweaks to make them more specific to the variant.