"I can not abandon this tool as I can not abandon nuclear deterrence", he told the Daily Telegraph in an interview that marked the end of his first year at Downing Street.
But the UK's main scientific adviser explained there is "a hazard" this sort of steps could be needed as wintertime techniques.
Next week, ministers will be handed sweeping new powers enabling them to ban travel in and out of hot-spot areas, which could see individual streets lock down or, potentially, entire towns.
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The prime minister said, "I can't abandon that tool any more than I would abandon a nuclear deterrent".
"The Heath and Safety Executive would certainly have something to say if they are not using all of the guidelines". He instead said that the government's plan is to "hope for the best, but plan for the worst".
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A league spokesman said: "Clearly today's significant announcement by the prime minister starts to provide some clarity as we collectively work towards the reopening of turnstiles and welcoming fans back into stadia at EFL clubs".
Johnson set out the latest timetable for easing on Friday, saying employers would be given more discretion over working from home rules, that the safety of larger gatherings would be evaluated, and that social distancing rules might be dropped in time for Christmas.
What this means is that, currently, if a person has previously been diagnosed with COVID-19 but dies of unrelated causes, their death is still counted as a coronavirus death.
The government will also increase testing capacity and flexibility, bolster its stockpiles of protective equipment and, wary of increased pressure from other seasonal illnesses, increase its annual flu vaccination programme.
"Now, however, we know more about the virus, we understand the epidemiology better and our intelligence about where it is spreading is vastly improved".
On Friday, UK leader said that the country could return to normality from the virus outbreak by Christmas.
He said: "What we don't want to do is re-import it and the idea of the quarantine is the right thing to do and it has broad public support".
He added: "The message has been quite consistent in that we must be alert and we must be socially distanced and if we are really super-careful and if we are able to follow all the rules it does seem to me that we should expect there to be a relative flatline at the moment ..."
He stated that while the Civil Service was "completely amazing", lessons could be realized from the pandemic.
"But maybe there are ways in which we can all learn together to do things faster, to have a real spirit of "can do". I feel in some cases it is a problem of confidence and belief", he claimed.
Meanwhile, the UK's National Statistician Professor has said a V-shaped economic recovery after coronavirus is still possible. "And nor do I feel we will be in that situation again", he reported.
The estimate does not take into account any lockdowns, therapies or vaccines.
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