London NHS chiefs have been warned of a looming third Covid wave driven by a cocktail of Omicron and Delta mutations.
Health service executives in the capital predict the wave could peak by January 13.
But there is still much uncertainty and the top of the spike could be seen a week earlier, the New Statesman reports.
The wave's magnitude is worrying bosses, who expect all available Covid surge beds in the capital will be full by the start of the new year.
Staff are trying to clear space for incoming patients by discharging others, but bosses don't think it will free up enough beds.
A letter sent to NHS trusts earlier this week set out detailed instructions for virus surge planning.
Officials expect the third wave's peak will have around half the impact of January 2021's second wave - when seven-day averages reached near 60,000 confirmed infections and deaths soared over 1,200 daily.
Hospitalisations peaked at 39,254 on January 18, with 8,739 over the seven days before January 23.
Despite only having half the impact, concerns have been raised of significant pressure being heaped on the health service - while its general activity is higher than last year.
Experts predict it will take less than two weeks for Omicron to become the dominant UK variant.
The mutation is responsible for 44 per cent of London cases, while it represents just 20 per cent in the rest of England.
Ministers expect the strain will become dominant in a matter of days rather than weeks.
NHS England declined to comment on the reports.
Meanwhile, experts have warned that hospital admissions could reach 2,000 a day and that it could take just four weeks for the virus to overwhelm the NHS.
Leading infectious disease scientist, Graham Medley, told BBC Radio 4's Today programme: "Most of the infections at the moment are in young adults, so these are people who are far less likely to need hospital treatment in any case.
"But in the past, in previous waves, we've seen that move out into more older and more vulnerable generations and there's no reason to suspect that won't happen during this wave.
"And then the numbers of people who end up in hospital is some combination of when people get infected, their vaccination status, as well as what Omicron is doing."
"I think it is a very real possibility that if the numbers of infections increasing continues in the way that it has done and it spills out into older age groups than we could see the number of people being omitted to hospital getting very large and certainly going over the thousand, maybe up to 2,000 a day", the scientist, who works at the London School of Hygiene and Tropical Medicine, added.
It comes after Cabinet ministers were warned it could take just four weeks for NHS hospitals to be completely overwhelmed.
