COVID passes will also be needed to get into nightclubs and large venues from next week.
Boris Johnson announced the government was moving to its back-up plan of extra COVID rules at a news conference.
Boris Johnson said moving to the tougher measures was the "proportionate and responsible" thing to do.
Mr Johnson said more is still being learned about the new variant Omicron and the picture might get better, but that it "could lead to a big rise in hospitalisations and therefore sadly in deaths".
He said the new variant was "growing much faster" than Delta and early analysis suggested cases could be doubling every 2.5 to three days.
Under the new rules:
- From Friday, 10 December, the government will further extend the legal requirement to wear a face mask to most public indoor venues, including theatres and cinemas. There will be exemptions in venues where it is not practical to wear one, such as when you are eating, drinking or exercising.
- From Monday, 13 December, those who can will be advised to work from home. Employers should use the rest of this week to discuss working arrangements with their employees.
- From Wednesday, 15 December, and subject to parliamentary approval, the NHS Covid Pass on the NHS App will become mandatory for entry into nightclubs and settings where large crowds gather – including unseated indoor events with 500 or more attendees, unseated outdoor events with 4,000 or more attendees and any event with 10,000 or more attendees.
- People will be able to demonstrate proof of two vaccine doses via the app. Having considered the evidence since the emergence of Omicron, proof of a negative lateral flow test will also be accepted.
- As Omicron spreads in the community, the government also intends to introduce daily contact tests for contacts of confirmed positive Omicron cases instead of the ten-day self-isolation period
People will be able to demonstrate proof of two vaccine doses via the app, and proof of a negative lateral flow test will also be accepted.
The government will keep the data under constant review, with regulations set to expire six weeks after implementation, with a review after three weeks.
Following these guidelines, the government is hopeful these measures will reduce transmission and slow the spread of the Omicron variant.
They will continue to urge those eligible to get their boosters when called.
For more information visit, gov.uk