Boris Johnson announced further Plan B measures for England in a bid to slow the spread of the Omicron variant, which public health bosses say looks increasingly likely to take over from Delta as the dominant strain of coronavirus globally.

In a Downing Street press conference the prime minister announced new guidance on mask wearing and working from home, and said that NHS Covid passes would be needed to enter some large venues.

What are the new Covid-19 rules?

Until now, ministers had kept most of their Plan B measures in reserve for if Covid-19 cases rose so high that they placed the NHS under unsustainable pressure.

But with concerns mounting, the government has brought back stricter guidance.

  • People will be asked to work from home if they can.
  • Face masks will be brought back in for most indoor venues — including theatres and cinemas — and some outdoor venues.
  • Mandatory vaccine passports are being brought back for larger events and nightclubs, where people must prove they are double-jabbed or have recently tested negative.

Exceptions to wearing masks include when eating, drinking, exercising or singing, Mr Johnson said.

Venues include those indoors that are unseated with more than 500 people, unseated outdoor venues with more than 4,000 people and any venue hosting more than 10,000 people.

A negative lateral flow test will also be sufficient proof, with all measures coming into force in seven days’ time, Mr Johnson said.

Will the plan work to slow the spread of Omicron?

Professor Neil Ferguson, from Imperial College London, whose data was instrumental to the UK going into lockdown in March 2020, said on Wednesday that “case numbers of Omicron are doubling at least every three days, maybe even every two days at the moment, so it’s accelerating very fast”.

He said lockdowns are a possibility and cannot be ruled out, but working from home guidance could slow the spread.

“There is a rationale, just epidemiologically, to try and slow this down, to buy us more time principally to get boosters into people’s arms, because we do think people who are boosted will have the best level of protection possible, but also to buy us more time to really better characterise the threat,” he said.

He suggested “a kind of Plan B Plus with working from home might slow it down” rather than stopping Omicron, reversing the doubling time to every five or six days.

What does the Scientific Advisory Group for Emergencies (Sage) think?

Sage has said Plan B measures will have the greatest effect if brought in in one go.

Of the individual measures, the scientists advising the government believe working from home will have the biggest impact on slowing the spread of the virus.

The React study from Imperial College London showed working from home reduced the chance of catching Covid-19 during earlier stages of the pandemic.

Analyses of risk by occupation also shows a lower risk for those jobs with higher levels of working from home.

What are the chances of another lockdown?

The prime minister said Plan B measures do not amount to a lockdown, adding that people following the rules and the booster jab rollout were the path to a "Christmas as close to normal as possible".

Mr Johnson said: “On Christmas, the best way to ensure we have a Christmas as close to normal as possible is to get on with Plan B – irritating though it may be, it is not a lockdown, it is Plan B, it is what we set out a while back – and to get your booster and to get your jab.”

He said his aim was for restrictions to be in place “no later than early January and possibly before, if we start to get some of that really granular information but we need to see the data and work on it pretty hard”.

What are the rules in Scotland?

Vaccine passports are already in force and have been since October, with people who are attending nightclubs, indoor events (unseated) with 500 or more people, outdoor events (unseated) with 4,000 or more people and any event with 10,000 or more to show they are double vaccinated before entering.

Since December 6, a negative PCR test taken within 24 hours of entry to a venue or a negative lateral flow test have also been accepted as part of the passes. Scotland’s Covid passes are called the NHS Scotland COVID Status app.

What are the rules in Wales?

Vaccine passports are in force in cinemas, theatres, concert halls as well as nightclubs and large events.

They are also needed for unseated indoor venues with more than 500 people in the audience, outdoor or indoor unseated venues with a capacity over 4,000 and any event with more than 10,000 people.

The passes can be downloaded by people who are double vaccinated or have tested negatively within 48 hours of entering the venue.

Similarly to England, Wales uses the NHS Covid Pass.

What are the rules in Northern Ireland?

Northern Ireland has followed the same rules as Wales, which have been in place since November 29.

Enforcement will be applied from December 13. Residents who can download Covid passes include those who are double vaccinated or have tested negatively within 48 hours of entering the venue.

In Northern Ireland, the pass is called COVIDCert NI Mobile App.