People in England will be required to work from home again and face masks will be mandatory in most public places, in an effort to limit the spread of the Omicron variant.
Vaccine passports will also be needed to get into nightclubs and large venues from next week.
Boris Johnson announced the government was moving to Plan B – its back-up plan of extra Covid rules.
“It’s not a lockdown, it’s Plan B,” the prime minister told a news conference.
He said moving to the tougher measures was the “proportionate and responsible” thing to do.
Mr Johnson said more is still being learned about 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”.
The government’s Plan B – unveiled in September – is aimed at stopping the NHS coming under unsustainable pressure.
The measures just announced are:
- People urged to work from home where possible, from Monday
- Face masks to be required in more public settings such as theatres and cinemas – but not when eating, drinking, exercising or singing – from this Friday
- The NHS Covid Pass will be required for visitors to nightclubs, indoor unseated venues with more than 500 people, unseated outdoor venues with more than 4,000 people and any event with more than 10,000 people from next Wednesday. Lateral flow tests can also be used for entry
Parliament will debate the measures next week, with a vote expected to take place on Tuesday 14 December.