Amid rising concerns of a ‘tidal wave’ of Omicron in the UK, a new modelling study has shown that the super mutant strain may cause between 25,000 and 75,000 Covid-19 related deaths in the UK by April next year.

On Monday, the UK reported its first death from Omicron even as the latest variant of the coronavirus is expected to comprise 50 percent of the cases in London by Tuesday.

“Sadly yes, Omicron is producing hospitalisations and sadly at least one patient has been confirmed to have died with Omicron,” Prime Minister Boris Johnson said on Monday during his visit to the vaccination clinic near Paddington, in west London, according to media reports.

According to the World Health Organization, the Omicron variant reduces vaccine efficacy and spreads faster.

In line with this, the yet-to-be peer-reviewed study projected that under the assumption of low immune escape, the UK will see 24,700 deaths, while in the case of high immune escape, the country will witness 74,800 deaths.

“These results suggest that the introduction of the Omicron B.1.1.529 variant in England will lead to a substantial increase in SARS-CoV-2 transmission, which, in the absence of strict control measures, has the potential for substantially higher case rates than those recorded during the Alpha B.1.1.7 winter wave in 2020-2021,” said Rosanna Barnard from the London School of Hygiene and Tropical Medicine (LSHTM), who co-led the research.

“This is due to Omicron’s apparent high transmissibility and ability to infect individuals with existing immunity to SARS-CoV-2 from prior infection or from vaccination,” Barnard said.

The study 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 (low immune escape of Omicron and high effectiveness of boosters), 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 over and above the current ‘Plan B’ policy in England.

In this scenario, bringing in control measures early in 2022 which involved 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.

On the other hand, the most pessimistic scenario (high immune escape 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, with 492,000 hospitalisations and 74,800 deaths.

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.

“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,” Barnard said.

For the two immune escape scenarios considered, the team estimated the Omicron variant to be between 10 percent less transmissible than the Delta variant to 35 percent more transmissible than Delta.

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.

“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.

The study also acknowledged 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.