Even if the disease severity caused by the Omicron Covid variant is the same as Delta, hospitalisations are likely to increase if more people become infected, the World Health Organization (WHO) said.
Omicron has been reported in 57 nations and the number of patients needing hospitalisation is likely to rise as it spreads. However, there is limited data making it harder to assess, WHO added.
"Even if the severity is equal or potentially even lower than for Delta variant, it is expected that hospitalisations will increase if more people become infected and that there will be a time lag between an increase in the incidence of cases and an increase in the incidence of deaths," it said.
On November 26, the WHO declared the Omicron variant, which was first detected in southern Africa, a variant of concern. It is the fifth SARS-CoV-2 strain to carry such a designation.
Earlier this week an infectious diseases expert at the University of East Anglia Professor Paul Hunter said there were concerns the Omicron variant was “spreading rather more quickly than the Delta variant".
“How it’s likely to spread in the UK still uncertain, but I think the early signs are that it will probably spread quite quickly and probably start outcompeting Delta and become the dominant variant probably within the next weeks or a month or so at least,” Prof Hunter told BBC Breakfast on Monday morning.
He added that there may already be over 1,000 Omicron cases in the UK.
The number of reported Covid cases in South Africa doubled in the week to December 5 to more than 62,000 and "very large" increases in incidence have been seen in Eswatini, Zimbabwe, Mozambique, Namibia and Lesotho, it said.
The spread of Omicron, coupled with enhanced testing and low vaccination rates may have played a role, it added.
Referring to the risk of reinfection, the WHO said: "Preliminary analysis suggests that the mutations present in the Omicron variant may reduce neutralising activity of antibodies resulting in reduced protection from natural immunity."
"There is a need for more data to assess whether the mutations present on the Omicron variant may result in reduced protection from vaccine-derived immunity and data on vaccine effectiveness, including the use of additional vaccination doses," it said.
The Omicron variant can partially evade the protection from two doses of the Covid vaccine produced by Pfizer and BioNTech, the research head of a laboratory at the Africa Health Research Institute in South Africa said on Tuesday, reporting the results of a small study.
