The Army will return to the North West to help drive down rising rates of coronavirus thought to be caused by the Indian variant.
Despite soaring rates in some parts of the region including Bolton and Blackburn with Darwen, a planned easing of restrictions on indoor hospitality will still go ahead.
The Prime Minister added: "Colonel Russ Miller, Commander of the North West region will deployed to support local leaders in managing the response on the ground, there will be surge testing with mobile testing units and the army will be on the streets handing out tests."
The Prime Minister called on the people of Bolton and Blackburn to "play their part in stopping the spread of the new variant" and asked them to take the vaccine and the twice-weekly rapid tests.
"If you do test positive, you must self-isolate and we'll provide financial support to those on low incomes to help them do so," he said.
He added: "Our best chance of suppressing this variant is to clamp down on it, wherever it is and we'll be throwing everything we can (at it)."
The Prime Minister has refused to rule out a local lockdown in Bolton as cases of the Covid-19 Indian variant continue to sharply rise.
In the town, which has one of the highest case rates of the variant in the country, mobile testing units have been deployed and door-to-door PCR Covid testing has been offered to 22,000 residents.
A vaccine bus has been set up to increase uptake among those who are eligible and a rapid response team of 100 nurses, public health advisers and environmental health officers has been sent in.
Coronavirus cases almost doubled week-on-week, the latest Public Health England figures show, with the infection rate currently at 228.5 cases per 100,000 people - the highest in the UK.
A total of 657 new cases were recorded in the seven days up to 10 May, up 100 from the day before.
Blackburn with Darwen has the third worst rates, up from 56.8 per 100,000 to 111.6, with 167 new cases. Sefton is the eighth worst.
There will also be an acceleration of the vaccine rollout in Blackburn and Bolton, including longer opening hours at vaccination centres.
Mr Johnson said: "If you're seeing loved ones, think really carefully about the risk to them, especially if they haven't had that second dose or if it hasn't yet had time to take full effect."
He added: "I want us to trust people to be responsible, and to do the right thing. That's the way to live with this virus while protecting the NHS and restoring our freedoms.
"It's very clear now we're going to have to live with this new variant of the virus for some time so let's work together, and let's exercise caution and common sense."
But, Mr Johnson also said that the spread of the Indian variant could derail the proposed ending of restrictions in June.
He told the Downing Street press conference: "I do not believe that we need, on the present evidence, to delay our road map and we will proceed with our plan to move to step three in England from Monday.
"But I have to level with you that this new variant could pose a serious disruption to our progress and could make it more difficult to move to step four in June."