The current arsenal of coronavirus vaccines will probably be effective at preventing severe disease from the newly identified omicron variant, a top South African infectious disease expert said on Monday.

Professor Salim Abdool Karim added at a news conference that it was too early to say whether omicron led to more severe clinical symptoms than previous variants.

Meanwhile, in the UK, a government adviser warned there was “good cause to be concerned” about the new strain.

Professor Sir Mark Walport, a member of the Scientific Advisory Group for Emergencies (Sage), told Sky News it “makes sense to try and hold it back” even though it will be “impossible to stop it spreading around the world if it is much more infectious than the Delta variant”.

He said the most important thing people in the UK could do was to have vaccines and take measures such as wearing masks.

Asked if people should be told to wear masks in pubs and restaurants, Prof Walport said: “If you are in a small, poorly ventilated enclosed space, it makes sense to wear a mask. Clearly when you are drinking and eating it’s not possible to do that but if you’re moving around, then absolutely.

“We know that infection happens in closed spaces indoors and of course, as it gets colder, people are more likely to be indoors and they’re less likely to have the windows open.

“So if you’re going to wear masks in shops, it makes sense to wear them in other places as well.”

Contact tracers in Essex are investigating potential links to a person infected by the omicron variant of coronavirus.

A school and a KFC restaurant in Brentwood are among the locations under scrutiny, according to Dr Michael Gogarty, the county director of public health.

A new variant of Covid-19 has emerged and is causing concern around the world given its “incredibly high” number of mutations, with fears rife among experts because it is both highly transmissible and effective at evading the human body’s immune response, writes Joe Sommerlad.

First detected in Botswana, beginning to emerge in South Africa and already detected in Europe, B.1.1529 has been named omicron by the World Health Organisation after the next available letter of the Greek alphabet.

The deputy head of the Joint Committee on Vaccination and Immunisation (JCVI) has talked up the booster vaccine campaign as the first pillar of Britain’s response to the omicron variant of coronavirus.

Professor Anthony Harnden said there were two potential arms of the fightback.

“Either we raise the immunity in the population or we find a matched vaccine,” he told BBC Breakfast.

He added: “And it’s going to be quite a while before we can get a matched vaccine so it’s sensible to increase the immunity in the population and that will be done by actually encouraging those that are unvaccinated so far to get vaccinated, that is absolutely imperative, but also to make sure that we boost the most vulnerable in order.

“Inevitably everybody will be offered a booster but what we want to do is make sure that it’s done in a sensible order so that those that are most vulnerable for this infection can get boosted and their natural immunity levels can go up.”

Prof Harnden said the JCVI was looking at reducing the interval between second and booster doses and increasing the age range of who is eligible.

He said it was “really important that we get the immunity levels in the population high” in case the Omicron variant was more transmissible or protection from vaccines was reduced.

Scotland’s deputy first minister has said “some” of the six new omicron infections in the country were not linked to overseas travel.

John Swinney told Good Morning Scotland: “On some of the cases we are aware that there is no travel history involved.

“So what that tells us is that there must be a degree of community transmission of this particular strain of the virus.”

Portugal detected 13 cases of the new omicron coronavirus variant on Monday, all related to players and staff at Lisbon football team Belenenses, according to health authorities.

Deputy Labour leader Angela Rayner has said people should be wearing face coverings at indoor hospitality venues as a simple way of slowing the spread of the virus.

The new mask requirements only extend to public transport and shops – not theatres, restaurants, pubs and cinemas.

Speaking on BBC Breakfast, she said: “We think we should be encouraging people to wear masks when we’re all mixing indoors, as much as possible.

“So we would recommend that people do wear masks when they’re out and about, specially when they’re moving around venues.

“The prime minister unfortunately has undermined those messages in recent weeks, but wearing a mask can be a very protective way of supporting people in stopping the virus being able to spread as quickly.”

Japan has joined Israel in banning all foreign arrivals, while the UK is extending its own red list.

With restrictions changing by the hour, keep on top of how the omicron variant is affecting travel with our blog here:

Elsewhere on the morning media round, Health Minister Edward Argar said he was “confident” that NHS Test and Trace would be able to “scale up and meet the challenge” of the new coronavirus variant.

He told Times Radio: “What we sought to do with Test and Trace was to bring the local knowledge and expertise of local public health teams and combine it with external resource which gave the scalability and the ability to turn up the capacity in Test and Trace. We’re confident that Test and Trace can meet this challenge.

“And just by way of an example, I think 91 per cent of contacts, where they’re given by someone who tests positive at the moment, are being reached and contacted within the appropriate time.

“So it has come a long, long way from when it was first set up. And I’m confident it will be able to scale up and meet the challenge.”