People infected with the Omicron variant are much less likely to be admitted to hospital than those with Delta, the English public health body said on Thursday.
Estimates from the UK Health Security Agency have shown that people with Omicron are between 50 and 70% less likely to be hospitalized.
The UKHSA also found that people who received booster shots of the coronavirus vaccine more than 10 weeks ago were experiencing the first signs of declining immunity to symptomatic Omicron infection.
The findings on Omicron’s lower virulence compared to Delta are consistent with separate research from Imperial College London and the University of Edinburgh released on Wednesday, as well as healthcare data from South Africa, where the new variant was first identified. A growing body of evidence indicates that Omicron is less severe than Delta.
Scientists warn that any reduction in severity must be weighed against the fact that Omicron spreads much faster than Delta and is more likely to evade vaccines.
Agency research indicates that the protection offered by a vaccine booster against symptomatic Omicron infection appears to wane after about 10 weeks, although protection against hospitalization and serious illness is likely to last longer.
UKHSA chief executive Jenny Harries said the analysis “shows an encouraging early signal that people who contract the Omicron variant may be at a relatively lower risk of hospitalization than those who contract other variants.” .
But she added that “cases are currently very high in the UK, and even a relatively small proportion requiring hospitalization could lead to serious illness in a significant number of people.”
UK Health Secretary Sajid Javid said emerging information on Omicron was “encouraging news” but said it was “not yet very clear … how much this risk is reduced” compared to Delta.
The analysis follows two studies, from Imperial College London and Scottish researchers, which found that patients with Omicron were between 20% and 68% less likely to require hospital treatment than those with Delta .