Experts from the London School of Hygiene & Tropical Medicine (LSHTM) used experimental data to look at how Omicron may transmit.
Even under the most optimistic scenario (low immune escape of Omicron from vaccines and high effectiveness of booster jabs), a wave of infection is projected which could lead to a peak of more than 2,000 daily hospital admissions, with 175,000 hospital admissions and 24,700 deaths between December 1 this year and April 30, 2022.
This is if no additional control measures are implemented over and above the current Plan B introduced by the Government in England.
The team said mask-wearing, working from home and booster jabs may not be enough, predicting a peak of daily hospital admissions of 2,400 in January.
In this scenario, bringing in control measures early in 2022 – such as restrictions on indoor hospitality, the closure of some entertainment venues and restrictions on how many people can gather in one place – would be sufficient to substantially control the wave, reducing hospital admissions by 53,000 and deaths by 7,600.
The most pessimistic scenario looked at by the modellers (high immune escape from vaccines and lower effectiveness of boosters) projects a wave of infection which is likely to lead to a peak in hospital admissions around twice as high as the peak seen in January 2021, if no additional control measures are taken.
This could cause 492,000 hospital admissions and 74,800 deaths, according to the study, which has not yet been peer-reviewed.
In this scenario, the team estimates that stronger measures may be required to keep the peak number of hospital admissions below the January 2021 peak.
The scientists assumed Omicron causes the same severity of illness as Delta, but did not look at the impact of measures such as mass population testing to control its spread.
They said: “These results suggest that Omicron has the potential to cause substantial surges in cases, hospital admissions and deaths in populations with high levels of immunity, including England.
“The reintroduction of additional non-pharmaceutical interventions may be required to prevent hospital admissions exceeding the levels seen in England during the previous peak in winter 2020–2021.”
Dr Rosanna Barnard, from LSHTM’s Centre for the Mathematical Modelling of Infectious Diseases, who co-led the research, said: “More data over the next few weeks will strengthen our knowledge on Omicron and the consequences of this on transmission in England.
“However, these early projections help guide our understanding about potential futures in a rapidly-evolving situation.
“In our most optimistic scenario, the impact of Omicron in the early part of 2022 would be reduced with mild control measures such as working from home.
“However, our most pessimistic scenario suggests that we may have to endure more stringent restrictions to ensure the NHS is not overwhelmed.
“Mask-wearing, social distancing and booster jabs are vital, but may not be enough.
“Nobody wants to endure another lockdown but last-resort measures may be required to protect health services if Omicron has a significant level of immune escape or otherwise increased transmissibility compared to Delta.
“It is crucial for decision-makers to consider the wider societal impact of these measures, not just the epidemiology.”