Liverpool, Warrington, Hartlepool and Middlesbrough have become the latest regions to enter local lockdowns, resulting in more than a third of the UK population living under heightened restrictions.
The new restrictions on northwest England, similar to those imposed in the North East earlier this week, took effect from 12.01am on Saturday.
During his announcement Health Secretary Matt Hancock urged residents in the four regions not to socially mix with those from other households – except in outdoor spaces like parks and outdoor hospitality settings.
And he asked them to avoid “all but essential travel” – meaning people can still go to work and school.
Mr Hancock said the measures were needed because “in some parts of the country, the virus is spreading fast”, with cases shooting up to 268 per 100,000 people in Liverpool.
But the second spike in COVID-19 cases was “highly localised”, he claimed, adding recent actions were having a “positive impact”.
The prime minister has defended the current raft of local lockdowns and pleaded for patience in the struggle against the disease.
Mr Johnson has faced a revolt on his backbenches in recent days over the way ministers have introduced such local lockdowns without giving MPs a say.
But in an interview with the Telegraph he said there was a “moral imperative” to bring in life-saving measures during what he called a “once-in-a-century event”.
Addressing the unpopularity of the 10pm pub curfew and other social restrictions, the PM told the paper he sympathised “with people who chafe at the restrictions”.
He added: “I think everybody is fed up – I just urge people to be a little bit patient.
“We will get through it and we will save a load of lives, and that’s really the best I can say.
“I think there is a moral imperative to save life where you can.”
His comments come as yet more university students tested positive, with Northumbria University, based in Newcastle-upon-Tyne, saying that as of Friday it was aware of 770 cases, 78 of whom are symptomatic.
New figures showed the reproduction number, or R value, of coronavirus transmission across the country still remains above 1, and is continuing to creep up.
The data released by the government advisory committee SAGE shows the estimate for R for the whole of the UK – the rate at which the virus is spreading – is between 1.3 and 1.6. Last week, the R number was between 1.2 and 1.5.