Ministers may be forced to close schools to older children if coronavirus cases continue to soar, a top scientist warns.
Professor Neil Ferguson, whose modelling led to the original lockdown in March, said the NHS would soon be unable to cope unless the spread of the disease was curbed.
He said there were currently 8,000 people in hospital with coronavirus – around a third of the peak earlier this year – and that numbers were continuing to rise.
Meanwhile research suggests the nation might not be able to “get on top of” the spread without resorting back to virtual education for older pupils.
Speaking to BBC Radio 4 Today programme, Prof Ferguson said: “It is a worrying situation.
“If the rate of growth continues as it is it means that in a month’s time we will above that peak level in March and that is probably unsustainable.
“We are in a critical time right now. The health system will not be able to cope with this rate of growth for much longer.”
The warning came as South Yorkshire became the latest region to enter the tightest Tier 3 restrictions in England following Liverpool City Region, Greater Manchester and Lancashire.
Tier 3 measures are the strictest under the Government’s new traffic light system which is hoped to slow the spread of the virus.
But it will be another week or two before it becomes clear whether the stricter measures would have an impact on case numbers, according to Prof Ferguson.
The scientist said the restrictions on households mixing should have a “significant effect” but added it may not be enough and further action may be needed.
Prof Ferguson added: “If we go beyond that there is a limit to what we can do in terms of reducing contacts, short of starting to target, for instance, the older years in schools and sixth form colleges where we know older teenagers are able to transmit as adults.
“Of course, nobody wants to start moving to virtual education and closing schools even partially.
“The challenge may be that we are not able to get on top of the transmission otherwise.”