The UK National Health Service can avoid becoming overwhelmed only if the Omicron variant turns out to be five to 10 times milder than Delta, according to new modelling.
But if Omicron turns out to be just half as severe as Delta, UK hospitalisations could exceed those seen at the peak of the second wave, suggested the study by the University of Warwick.
"Under these assumptions of no additional control (beyond Plan B), and even assuming omicron is just 10 per cent the severity of delta it is still highly likely that hospital admissions will peak above 1,500 per day," the authors were quoted as saying by the Telegraph.
"If we assume that Omicron is as severe as Delta then admissions will be an order of magnitude larger, peaking at around 27,000 admissions."
Data from recent Scotland study suggested Omicron is associated with a two-thirds reduction in risk of hospitalisation when compared with Delta.
A separate study by Imperial College London looking also suggested people with PCR-confirmed Omicron infection were 15 to 20 per cent less likely to require hospitalisation.
But, the Warwick authors noted that assuming the Omicron is 100 per cent as severe as Delta represents a "reasonable worst case", the researchers said.
They also cautioned that if the time it takes Omicron to become symptomatic is shorter than with Delta, as it is now strongly suspected, would radically alter their results for the better.
"If the generation time of Omicron was half that of Delta, once the model is recalibrated... this would approximately halve the predicted peak outbreak sizes", they said.
During the second wave of coronavirus, the number peaked at 34,336 on January 18.
As of Sunday, the UK has registered a total of 13,174,528 Covid-19 cases and 149,251 deaths.
Watch the latest DH Videos here:
Deccan Herald is on WhatsApp Channels| Join now for Breaking News & Editor's Picks