WHO, in its weekly epidemiological report, said more data was needed to assess the severity of disease caused by the Omicron variant, and whether its mutations might reduce protection from vaccine-derived immunity.

“Even if the severity is equal or potentially even lower than for the 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.

Referring to the risk of reinfection, 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”

The Omicron variant can partially evade the protection from two doses of the Covid-19 vaccine produced by Pfizer Inc and BioNTech, said the research head of a laboratory at the Africa Health Research Institute in South Africa on Tuesday, reporting the results of a small study.

Sources: Reuters, WHO, The Straits Times