The prime minister, leading the daily coronavirus press conference in Downing Street for the first time in five weeks following his own COVID-19 ordeal, said on Thursday that the transmission rate is “on the downward slope”.
Referring to the draconian lockdown imposed on 23 March, Johnson said: “Your effort and your sacrifice is working.
“It’s thanks to that massive collective effort to shield the NHS that we avoided an uncontrollable and catastrophic epidemic where the reasonable worst-case scenario was 500,000 deaths.
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“I can confirm today that for the first time, we are past the peak of this disease and we are on the downward slope.”
Sir Patrick Vallance, the government’s chief scientific adviser, confirmed the number of new cases, hospital admissions, intensive care admissions and deaths is beginning to fall.
Johnson, whose partner Carrie Symonds gave birth to a baby boy on Wednesday, said he will set out a “comprehensive plan next week” detailing how the UK will start to come out of the lockdown, focusing on the economy, schools and travelling to work.
The lockdown will be reviewed next Thursday, though the PM warned a “bad” second coronavirus peak would do “lasting” damage to the economy if the restrictions are lifted too quickly.
Johnson also hinted the use of face coverings will be advised as part of measures for easing the lockdown.
He said: “I do think that face coverings will be useful both for epidemiological reasons but also for giving people confidence they can go back to work.
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“But you’ll be hearing more about that thing next week,” he added. Scotland issued a recommendation to wear face coverings on Tuesday.
It comes after Johnson announced a further 674 patients had died in hospitals, care homes and the wider community, taking the UK’s death toll to 26,711. This is the third highest in the world.
The PM had earlier urged Britons to “keep going” with social distancing measures.
Before leading Thursday’s briefing, Johnson wrote on Twitter that he “understands” the public’s “impatience” and “anxiety” regarding the lockdown measures.
He said: “I know how hard and how stressful it has been to give up even temporarily those ancient and basic freedoms.
“But I must ask you to keep going in the way that you have kept going so far, so we can protect our NHS and save lives.”
Earlier, a former Tory MP has hit out at Johnson’s coronavirus response, describing it as “unacceptable”.
Dr Phillip Lee, who quit the Conservatives in 2019 in protest at the PM’s handling of Brexit, said his government has “failed spectacularly” during the COVID-19 pandemic.
Dr Lee, who lost his seat in the 2019 general election when he stood as a Liberal Democrat, told LBC: "The scale of unnecessary loss of life in this country is unacceptable. What angers me most is we could have done so much better.
"We have to ask ourselves why our governance has failed so spectacularly."