Prime Minister Boris Johnson has ruled out lifting the UK's lockdown as he told the nation it was the "moment of maximum risk".
In his first address since returning to work on Monday, Mr Johnson urged business leaders to be patient as he warned of the risk of a second wave.
"I can see the long term consequences of lockdown," he said.
"It's the Government's urgency. But we must also recognise the risk of a second spike.
"I ask you to contain your impatience because I believe we are coming to the end of the first phase of this conflict. We have so far collectively shielded our NHS... from an outbreak that would have been far worse."
Appearing outside Downing Street he thanked the nation for its "sheer grit and guts" as he said coronavirus is the single biggest challenge the UK has faced since the war.
He said the country is "beginning to turn the tide" but warned "it is the moment of maximum risk".
"We are making progress with fewer hospital admissions, fewer covid patients in intensive care units and there are real signs we are passing through the peak," he said.
"If this virus were a physical assailant, an unexpected and invisible mugger, which I can tell you from personal experience it is, then this is the moment when we have begun together to wrestle it to the floor and so it follows that this is the moment of opportunity.
"This is the moment when we can press home our advantage, it is also the moment of maximum risk because I know that there will be many people looking now at our apparent success and beginning to wonder whether now is the time to go easy on those social distancing measures."
He warned that if measures were eased too early and gave way to a second wave it would be an "economic disaster".
"I understand your impatience, I share your anxiety and I know that without our private sector without the drive and commitment of the wealth creators of this country there will be no economy to speak of," he said.
"There will be no cash to pay for our public services, no way of funding our NHS and yes I can see the long term consequences of lock down as clearly as anyone and yet we must also recognise the risk of a second spike, the risk of losing control of that virus because that would mean not only a new wave of death and disease but also an economic disaster.
"We would be forced once again to slam on the brakes across the whole country and the whole economy and reimpose restrictions in such a way as to do more and lasting damage and so I know it is tough and I want to get this economy moving as fast as I can but I refuse to throw away all the effort and the sacrifice of the British people and to risk a second major outbreak and huge loss of life and the overwhelming of the NHS."
Mr Johnson said a decision on the lifting of the lockdown will depend on scientific advice.
"We simply cannot spell out now how fast or slow or even when those changes will be made," he added
"Though clearly the government will be saying much more about this in the coming days."
It is exactly one month since Mr Johnson went into isolation after contracting a severe case of Covid-19, which put him in intensive care and left the UK without its leader as the country entered the peak of the outbreak.
Closing his speech, Mr Johnson urged he country to carry on.
"If you can keep going, if you can continue to protect our NHS and save lives and if we as a country can show the same spirit of optimism and energy shown by Captain Tom Moore," he added.
"If we can show the same spirit of unity and determination as we have all shown in the past six weeks then I have absolutely no doubt that we will beat it together. We will come through this all the faster and the United Kingdom will emerge stronger than ever before."
Mr Johnson had returned to his office at 10 Downing Street on Sunday night.
Later on Monday he is due to chair his first meeting of the Covid-19 cabinet.
“It’s great that he’s back and able to take the reins again,” Health Minister Edward Argar said earlier on Monday.
“He’s very much back in charge and back at his desk.”
Mr Johnson has spent the past two weeks recuperating at Chequers, his official country residence, and has been gradually easing himself back into his duties, with calls to his ministers and others.
With the nation recording its lowest daily death toll since March and lockdowns being partially lifted on the European continent, the premier is facing increasing pressure to explain how and when his administration will start to lift the restrictions that are hurting the economy. The government will review the lockdown on May 7.
"It's too early at the moment to speculate what might or might not come through in any changes," Mr Argar told BBC News on Monday.
Businesses are “clamoring” for information, the Institute of Directors said.
A survey of more than 1,000 business leaders showed fewer than one in four were optimistic for their prospects over the next 12 months. Chancellor of the Exchequer Rishi Sunak is due to make a statement to Parliament later Monday on the impact of the lockdown on the economy.
Six business leaders, including Conservative Party billionaire donors Michael Spencer and Peter Hargreaves, have written to the government asking them to ease restrictions.
Opposition Labour leader Keir Starmer wrote to Mr Johnson calling for an “exit strategy”.
On Sunday, Foreign Secretary Dominic Raab, who has been deputising for Mr Johnson while the premier was out of action, rejected the calls for an early easing of the lockdown, telling Sky News the outbreak was still at a “delicate and dangerous” stage.
On Sunday, the UK reported 413 hospital deaths from the previous day, taking the tally to almost 21,000, the fifth highest in the world. More than 150,000 people have tested positive for the virus.