Omicron has lower risk of hospitalization than Delta, study finds – National

South African study suggests reduced risks of hospitalization and serious illness in people infected with Omicron coronavirus variant compared to Delta, although the authors say this is likely due to high population immunity.

Questions about Omicron’s virulence are at the heart of scientific and political debate in many countries, as governments grapple with how to respond to the spread of the variant as researchers rush to figure it out.

The new study, which was not peer-reviewed, aimed to assess the severity of the disease by comparing data on Omicron infections in October and November with data on Delta infections between April and November, all in South Africa.

The analysis was carried out by a group of scientists from the National Institute of Communicable Diseases (NICD) and leading universities, including the University of the Witwatersrand and the University of KwaZulu-Natal.

They used data from four sources: national data on COVID-19 cases reported to NICD, public sector laboratories, a large private sector laboratory, and genomic data for clinical samples sent to NICD by laboratories from private and public diagnosis across the country.

The authors found that the risk of hospitalization was about 80% lower for people infected with Omicron compared to Delta, and that for people who were hospitalized, the risk of serious illness was about 30% lower.

0:59COVID-19: Still too early to say if the Omicron variant is less serious than Delta, according to the WHO

However, they included several caveats and cautioned against hasty conclusions about the intrinsic characteristics of Omicron.

“It is difficult to disentangle the relative contribution of the high levels of immunity of the previous population versus lower intrinsic virulence at the lower severity of disease observed,” they wrote.

Paul Hunter, professor of medicine at the British University of East Anglia, called the South African study important and said it was the first properly conducted study to appear in preprinted form on the issue of Omicron gravity versus Delta.

But Hunter said his main weakness was that he compared Omicron data from one period with Delta data from an earlier period.

“So even though the Omicron cases were less likely to end up in hospital than the Delta cases, it is not possible to say whether this is due to inherent differences in virulence or whether it is due to higher immunity of the population in November compared to the start of the year, ”he said.

“To some extent, it doesn’t matter to the patient who just cares about not getting very sick. But it is important to know to allow a better understanding of the likely pressures on health services. “

The results of a major Imperial College London study released last week showed there was no sign that Omicron was milder than Delta, although hospitalization data remains very limited.

It has not been peer reviewed and published in a medical journal.

(Report by Estelle Shirbon Editing by Josephine Mason and Mark Potter)