A person with the Omicron-Covid-19 variant is “50 to 70% less likely to be hospitalized” than a person with the Delta strain, UK government public health experts said.
The UK Health Security Agency (UKHSA) released preliminary results of its research on the new variant, saying Omicron appears to lead to less severe illness in those infected.
However, the agency warned that the new strain is more communicable than previous variants like Delta and could still result in significant numbers of people in need of hospital treatment in the coming weeks.
The results of the research are in line with those of three other early studies on Omicron that were published Wednesday.
Health Minister Sajid Javid hailed the latest data as “promising” but urged the public to remain cautious over the Christmas break, adding that it was “too early to determine next steps”.
According to an analysis by the UKHSA, the risk of hospitalization in an identified case with Omicron is reduced compared to a case with Delta.
It is estimated that someone with Omicron is 45% less likely to attend an A&E and 70% less likely to be hospitalized compared to Delta.
However, Omicron is believed to infect more people who have previously had Covid, with 9.5% of people with Omicron having previously.
Vaccination is also believed to offer less protection against Omicron, although a booster dose offers more protection against symptomatic illness compared to the first two doses alone.
The data suggest that protection wears off 10 weeks after the booster dose.
The agency has also warned that Omicron’s faster transmission rate than Delta could mean large numbers of people are likely to be hospitalized, putting a lot of pressure on the NHS.
Three research papers were released on Wednesday in support of the claims.
Research from Imperial College London shows that people with PCR-confirmed Omicron are 15 to 20% less likely to be hospitalized and 40 to 45% less likely to need a night or more stay.
However, researchers have added that while Omicron appears to be less severe, it is more transmissible, in part because the current crop of coronavirus vaccines is less effective against it.
The Imperial study, which has not yet been peer-reviewed, was based on PCR-confirmed coronavirus cases in both vaccinated and unvaccinated individuals registered between December 1 and 14 in England.
This sample included 56,000 Omicron cases and 269,000 Delta cases.
Early pandemic assessment and improved surveillance
Scientists in a Scotland-wide study called Early Pandemic Evaluation and Enhanced Surveillance of Covid-19 said Omicron has been linked to a two-thirds lower risk of hospitalization compared to Delta.
The authors of the Scotland paper, which has yet to be peer-reviewed, said if Omicron had been like the Delta variant in Scotland, they would have seen around 47 people in hospital with the virus, but so far there are only 15 .
University of Edinburgh Professor Mark Woolhouse said the data was severely limited as it was based on a small number of cases that weren’t attended by many people over 65.
The Omicron strain is the predominant type of virus in Scotland today, with cases of the variant increasing in the United Kingdom.
National Institute for Communicable Diseases
A South African study suggests a lower risk of hospitalization and serious illness in people infected with the Omicron coronavirus variant compared to the Delta variant – although the authors say some of this is likely due to the high immunity of the population is.
The new, non-peer review study attempted to assess disease severity by comparing data on Omicron infections in October and November with data on delta infections between April and November in South Africa.
The analysis was carried out by a group of scientists from the National Institute of Communicable Diseases (NICD) and major universities such as the University of the Witwatersrand and the University of KwaZulu-Natal.
They used data from four sources: national Covid-19 case data reported to the NICD, public sector laboratories, a large private sector laboratory, and clinical specimen genomic data sent to the NICD by private and public diagnostic laboratories across the country.
The authors found that those infected with Omicron were about 80% less likely to be hospitalized compared to those infected with Delta, and those who were hospitalized were about 30% less likely to develop serious illness.
However, they included several caveats and cautioned against jumping to conclusions about Omicron’s intrinsic properties.