South African study suggests lower risk of hospitalization with omicron versus delta

A South African study suggests that there is a lower risk of hospitalization and serious illness in people infected with the omicron variant of the coronavirus than those infected with delta, although the authors state that part of this is probably due to the high immunity of the population.

Questions about omicron virulence are at the center of scientific and political debate in many countries, as governments struggle to respond to the spread of the variant while researchers scramble to understand it.

The new study, which has not been peer-reviewed, tried to assess the severity of the disease by comparing data on omicron infections in October and November with data on delta infections between April and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 from South Africa.

The analysis was conducted by a group of scientists from the National Institute of Communicable Diseases (NICD) and leading 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 major private sector laboratory, and genome data from clinical samples submitted to the NICD from private diagnostic laboratories. and audiences across the country.

The authors found that the risk of hospital admission was approximately 80% lower for those infected with omicron compared to those with delta, and that for those who were hospitalized the risk of serious illness was approximately 30% lower.

However, they did include several caveats and advised that no hasty conclusions should be drawn about the intrinsic characteristics of omicron.

“It is difficult to distinguish between the relative contribution of the high levels of previous immunity in the population and the lower intrinsic virulence to the lower severity of the disease observed.”They wrote.

Paul Hunter, a professor of medicine at the British University of East Anglia, described the South African study as important, saying it was the first properly conducted study to appear in preprint form on the question of omicron versus delta severity.

But Hunter said its main weakness was that it compared omicron data from one period to delta data from a previous period.

“Thus, although omicron cases were less likely to end up in hospital than delta cases, it is not possible to say whether this is due to inherent differences in virulence or if it is due to increased immunity in the population in November compared to beginning of the year“, He said.

“To a certain extent, this does not matter to the patient, who only worries not to become seriously ill. But this is important to know in order to better understand the likely pressures on health services.”.