Without action to stem the tide of cases, it would be “impossible” for the health service to cope in the coming weeks, academics said.
The NHS could be overwhelmed “within weeks” without drastic action to tackle the spread of Covid-19, experts have warned.
Ministers fear that hospitals could fill up with rising coronavirus admissions.
Sir Jeremy Farrar, director of the Wellcome Trust, said: “Doctors and scientists agree that none of the current restrictions have been enough to stop the virus spreading.
“Without a change, the NHS would have been overwhelmed within weeks and it would have been difficult if not impossible to cope in the winter months with the inevitable increase in caring for people with Covid as well as non-Covid illnesses.
“There’s absolutely no doubt that many more of us would have seen loved ones die, suffer with long-term Covid symptoms or from other illnesses.
“The only way to get things back to normal quickly is to get the virus under control as soon as possible.”
Dr Shaun Fitzgerald, Royal Academy of Engineering visiting professor at the University of Cambridge, added: “None of us want this at all.
“But it now seems there is no choice if we are to avoid letting thousands and thousands more die, and the health service swamped to an extent that even non-Covid patients are seriously affected.”
The news comes as the UK recorded more than one million lab-confirmed cases of coronavirus since the start of the outbreak, according to Government data.
And hospitals are feeling the pressure as cases rise.
There are now almost 11,000 people in hospitals across the UK – including 978 on ventilators.
And many hospitals are treating more patients than they were at the height of the first wave of the pandemic.
A number of hospitals have been forced to postpone some of their other work to cope with the pressures of Covid-19 patients.
25,000 people in hospitals
Experts said last week that it was “not unrealistic” to think that there could be 25,000 people in hospitals by the end of November.
Along with rising case numbers and hospital admissions, there has been a rise in the number of deaths.
In September, the Government’s chief scientific officer warned that the UK could be facing 50,000 new Covid-19 cases a day by mid-October, leading to 200 deaths a day a month later.
But the Government said a further 326 people had died within 28 days of testing positive for Covid-19 as of Saturday.
Figures published by the UK’s statistics agencies for deaths where Covid-19 has been mentioned on the death certificate, together with additional data on deaths that have occurred in recent days, show there have now been 62,000 deaths involving Covid-19 in the UK.