People infected with the Omicron coronavirus variant are much less likely to be admitted to hospital than those with Delta, England’s public health body said on Thursday, as the UK reported a record 119,000 Covid-19 cases.
Estimates from the UK Health Security Agency showed that people with Omicron were between 50 and 70 per cent less likely to require an overnight stay in hospital.
The UKHSA also found that people who received coronavirus vaccine booster shots more than 10 weeks ago were facing the first signs of waning immunity against symptomatic infection from Omicron.
The findings on Omicron’s lower virulence compared to Delta are consistent with separate research from Imperial College London and the University of Edinburgh published on Wednesday, alongside healthcare data from South Africa, where the new variant was first identified. A growing body of evidence points towards Omicron being less severe than Delta.
Sajid Javid, UK health secretary, said the UKHSA findings were “promising” but warned that Omicron cases were increasing at “an extraordinary rate”. “Hospital admissions are increasing, and we cannot risk the NHS being overwhelmed,” he added.
But Boris Johnson’s cabinet is deadlocked on whether new Covid restrictions should be imposed in England after Christmas.
The prime minister has promised to recall parliament in the event of new regulations being introduced, which would set up another clash with his front bench and further rebellion by Conservative MPs.
On Thursday, the UK recorded 119,789 Covid-19 cases in the latest 24-hour period, a new record daily figure for the pandemic, underlining the rapid spread of Omicron across the country.
The government’s scientific advisers said that even if Omicron is less severe than Delta, the NHS could still be overwhelmed.
“A large wave of hospitalisations would be likely to follow a large wave of infections, even if there were a reduction in intrinsic severity,” said minutes from a meeting of the government’s Scientific Advisory Group for Emergencies, released on Thursday.
The scientific advisers said the intrinsic severity of Omicron would need to fall by “around 90 per cent” compared to Delta for hospital admissions “to not reach the levels of previous peaks”.
The UKHSA latest analysis of Omicron was based on 132 people infected with the variant who sought hospital treatment in England up to December 20, adjusting for factors including age, underlying health conditions and vaccination status.
The public health body found that people infected with Omicron were 31 to 45 per cent less likely to go to a hospital accident and emergency department compared to those with Delta.
Government officials said the reduction in Omicron’s severity stems from a combination of breakthrough infections in vaccinated people and reinfections caused by the variant being milder, and a potential change in the biology of the virus.
The UKHSA said its findings were “preliminary” and affected by the “small numbers of Omicron cases currently in hospital, inability to effectively measure all previous infections and the limited spread of Omicron into older age groups”.
A separate UKHSA analysis found that people initially given the Oxford/AstraZeneca vaccine who later received an mRNA booster shot had their protection against symptomatic infection from Omicron fall from 60 per cent after two to four weeks to between 35 and 45 per cent 10 weeks after the third dose.
For people who received three BioNTech/Pfizer shots, vaccine effectiveness dropped from 70 per cent to about 45 per cent after 10 weeks. For those who received two jabs of Pfizer followed by a Moderna third dose, vaccine effectiveness stayed between 70 and 75 per cent after 10 weeks.
The government’s vaccine advisers are considering the case for recommending fourth doses to offset waning immunity.
But decisions by the Joint Committee on Vaccination and Immunisation are contingent on data about vaccine effectiveness against severe disease.
In London, where Omicron spread most quickly in the UK, the number of people being treated in hospital primarily for severe Covid-19 has climbed 25 per cent in the past week, to 1,197 Covid patients as of December 19.
Matthew Taylor, chief executive of the NHS Confederation, which represents organisations across the healthcare sector, said the health service was facing “a double emergency” as “hospitalisations climb” and “rapidly rising numbers” of staff have to isolate because of Omicron.