London, December 13: The Omicron variant of coronavirus could cause between 25,000 and 75,000 COVID-19 related deaths in the UK by April next year, if additional control measures were not taken, according to a modelling study. The yet-to-be peer-reviewed study suggests that Omicron has the potential to cause a wave of transmission in England that could lead to higher levels of cases and hospitalisations than those seen during January 2021.

The researchers from the London School of Hygiene & Tropical Medicine (LSHTM) in the UK used the latest experimental data on the antibody-evading characteristics of Omicron to explore plausible scenarios for the immune escape of the variant.

Under the most optimistic scenario, a wave of infection is projected which could lead to a peak of over 2,000 daily hospital admissions, with 175,000 hospitalisations and 24,700 deaths between December 1, 2021 and April 30, 2022, if no additional control measures are implemented. Intranasal COVID-19 Vaccine May Aid Fight Against New Coronavirus Variant Omicron: Study.

The optimistic scenario assumes a low immune escape of Omicron and high effectiveness of vaccine boosters. In this scenario, bringing in control measures early in 2022 which involve restrictions on indoor hospitality, closure of some entertainment venues, and restrictions on gathering sizes would be sufficient to substantially control this wave, reducing hospitalisations by 53,000 and deaths by 7,600.

The most pessimistic scenario assumes a high immune escape and lower effectiveness of vaccine boosters. This scenario 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, with 492,000 hospitalisations and 74,800 deaths.

"There is a lot of uncertainty about the characteristics of Omicron, and whether Omicron in England will follow the same course as it has in South Africa," said Rosanna Barnard from LSHTM, who co-led the research.

"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," Barnard said.

In the 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, the researchers said. However, the most pessimistic scenario suggests that the UK may have to endure more stringent restrictions to ensure the health system is not overwhelmed, they said.

Mask-wearing, social distancing and booster jabs are vital, but may not be enough, according to the researchers. "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," Barnard said.

"It is crucial for decision makers to consider the wider societal impact of these measures, not just the epidemiology," she said. For the two immune escape scenarios considered, the team estimate the Omicron variant to be between 10 per cent less transmissible than the Delta variant to 35 per cent more transmissible than Delta. Omicron Variant Spreads Faster, Vaccines Less Effective Says WHO; UK Raises Covid-19 Alert Level After Rise in Cases.

The researchers account for the additional protection afforded by booster doses against Omicron in their scenarios. If a very high uptake of booster vaccines is achieved, then this is projected to further mitigate projected surges in cases, hospitalisations and deaths, they said.

"These are early estimates, but they do suggest that overall Omicron is outcompeting Delta rapidly by evading vaccines to a substantial degree," said Nick Davies from LSHTM, who co-led the research. "If current trends continue then Omicron may represent half of UK cases by the end of December," Davies added.

The researchers noted that these projections are subject to considerable uncertainty. The study has limitations including the early nature of the data used to make predictions, uncertainty over policy decisions that will be made over the next several months, and a lack of information on the relative severity of Omicron.