All the rule changes under Plan B and when they come into force

Work-from-home guidance will return, Covid health certificates are to become mandatory in large venues and mask rules will be extended to combat the Omicron variant as part of the Plan B measures announced by Boris Johnson.

The Prime Minister warned it is clear the new strain is “growing much faster” than Delta, and cases of Omicron could be doubling every two or three days as he strengthened England’s rules.

Mr Johnson said Christmas parties and nativities could go ahead, but urged people to “exercise due caution” and get their booster jabs as he came under pressure over allegations of a rule-breaching festive bash in No 10 last year.

What are the measures and when do they come into force?

The Prime Minister announce the move to Plan B at a press conference on Wednesday, the measures will be introduced in England.

He said: “The best way to ensure we all 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.

“We don’t want nativity plays to be cancelled, we think it’s okay currently on what we can see to keep going with Christmas parties but obviously everybody should exercise due caution.”

The measures set to come into force are:

• Mandatory mask wearing will be extended to indoor public venues including cinemas, theatres and places of worship from Friday but will not be required in pubs and restaurants

• The guidance to work from home where possible will return on Monday.

• The NHS Covid pass, which can be obtained by having two vaccines or a negative lateral flow test, will be introduced for entry into nightclubs and other large venues from 15 December

Covid health certificates will apply to unseated indoor venues with more than 500 attendees, and outside where there are more than 4,000 people.

The Prime Minister said passes can be obtained with a negative lateral flow test or by having had two doses of a vaccine, but hinted this could change by saying “we will keep this under review as the boosters roll out”.

How long will the measures be in place for?

Health Secretary Sajid Javid said the new restrictions would be reviewed on 5 January, before their expiry date of 26 January.

Mr Javid said the new restrictions were being imposed “with a heavy heart” but insisted they were necessary as he said there are 568 cases of Omicron confirmed in the UK, but that the true figure is estimated to be “probably closer to 10,000”.

The Scientific Advisory Group for Emergencies (Sage) warned Omicron is spreading “rapidly” and it is possible hospital admissions from the new variant in England could exceed 1,000 per day – and still be increasing – by the end of the year.

“The overall scale of any wave of hospitalisations without interventions is highly uncertain, but the peak could reach several times this level,” the minutes from a meeting held on Tuesday said.