'Plan B' Covid measures to come into force in England from Monday, PM confirms
The UK reported 131 new cases of the Omicron variant on Wednesday
Speaking at a Downing Street press conference, the Prime Minister said from Monday Brits should work from home "if you can".
He also announced that the legal requirement to wear masks would be extended from Friday to most indoor public venues, such as cinemas and theatres - although there will be exemptions for things such as eating - and vaccine passports would come into force.
Covid passes will become mandatory for nightclubs and venues where large crowds gather in England from next week.
This will include unseated indoor venues with more than 500 people, unseated outdoor venues with more than 5,000 people, and any venue with more than 10,000 people.
Johnson said two jabs will be sufficient for a Covid pass, but this will be kept under review as boosters are rolled out.
A negative lateral flow will also be acceptable.
The Prime Minister was due to make a call on Christmas in 10 days' time, on December 18, the same date last year when a Christmas party was said to have happened at Downing Street when Tier 3 restrictions were in place. Johnson has been grilled on the party all day, leading to his aide, Allegra Stratton, resigning.
Johnson refuted suggestions the 'Plan B' announcement was brought forward to "bounce" pressure off the Christmas party scandal.
Wednesday's announcement, he added, wasn't a "deviation" from plans, as the government had warned of possible threats back in September, but the "sudden emergence" of Omicron and the "potential numbers" it could produce, meant it had to act.
Johnson attempted to reassure Brits about Christmas, saying parties and nativity plays should go ahead, but "everyone should exercise due caution" and takes tests before attending.
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The announcement came after the UK recorded another 131 new cases of Omicron, bringing the total number of known infections to 568, up from 437 on Tuesday.
Johnson said Delta is growing "much faster" than Delta and cases were taking 2-3 days to double.
Prof Chris Whitty, England's chief medical officer, said while Omicron is not yet making a big dent in daily case numbers, "the data here is now clear", "Omicron is going up incredibly fast."
He said the aim of the Plan B measures is to "slow things down" as Omicron could go from "very small numbers to very large numbers quickly".
Whitty added that the booster shot campaign will become critical when Omicron "becomes significant and ultimately dominant".
As Omicron spreads, daily tests will be introduced instead of isolation to "minimise the disruption to daily life" Johnson said, as he reiterated his plea for people to get vaccinated:
NHS staff and volunteers have already done almost 21 million boosters, the PM said, but "we need to go further and faster still".