British Prime Minister Boris Johnson has said that he did not want another national lockdown but that new restrictions may be needed because the country was facing an "inevitable" second wave of Covid-19.
Britain is likely to need to reintroduce some national coronavirus lockdown measures sooner rather than later, a leading epidemiologist and former senior government health adviser has said.
Neil Ferguson, a professor of epidemiology at London's Imperial College, told the BBC on Saturday the country was facing a "perfect storm" of rising infections as people return to work and school.
"I think some additional measures are likely to be needed sooner rather than later," Ferguson said.
Ministers on Friday were reported to be considering a second national lockdown after new Covid-19 cases almost doubled to 6,000 per day, hospital admissions rose and infection rates soared across parts of northern England and London.
"Right now we're at about the levels of infection we were seeing in this country in late February, and if we leave it another two to four weeks we'll be back at levels we were seeing more back in mid-March, and that's going to — or could — cause deaths," Ferguson said.
Britain has suffered Europe's highest death toll from Covid-19, with more than 41,000 deaths on the government's preferred measure.
The sharp increase in infections has not yet led to a similar rise in new fatalities — in part because cases have been concentrated among younger people — but hospital admissions are now beginning to rise.
Stricter measures likely in London
Ferguson served on the government's main scientific advisory board until May, when he stepped down after breaking lockdown rules himself.
He said future lockdown restrictions did not need to be as strict as those introduced in March to be effective in slowing the renewed spread of the disease.
More than 10 million people in parts of northern and central England are already under some form of lockdown restriction, such as a ban on inviting friends or family to their homes, or visiting pubs and restaurants after 10 pm.
London's mayor, Sadiq Khan, said on Friday that tighter lockdown measures were becoming "increasingly likely" for Britain's capital.
Britain's capacity to test for coronavirus infections has also come under strain since schools in England reopened this month, with many people reporting that tests were unavailable or only possible at locations hundreds of miles away.
"We have a perfect storm right now, of people — as they have been told to do — getting back to normal, schools reopening, a surge in cases," Ferguson said.
Some local politicians have also expressed concern about whether businesses are collecting the details needed to track new infections.
Official figures on Friday showed that fewer than a third of people said businesses such as pubs and hairdressers always collected their contact details as legally required to, and a quarter reported never being asked for their details.