The Omicron variant appears able to get around some immunity but vaccines should still offer protection against severe disease, according to the latest data from South Africa where it is fast overtaking Delta to become the dominant variant.
Omicron, which has raised global fears of a surge in infections, was first detected in southern Africa last week and has prompted governments across continents to impose travel restrictions and take other measures to try and contain it.
The new variant has been detected in five out of nine South African provinces and is likely to be present all over the country.
The daily number of reported cases has doubled to 8,561. It is not known how many of these are Omicron as not all test samples are subject to genomic sequencing, but an official presentation said Omicron was "rapidly becoming the dominant variant".
Omicron dominant variant
Omicron accounted for 74% of the 249 virus genomes sequenced in South Africa in November, according to the National Institute for Communicable Diseases (NICD), which is collecting data as part of a wider national network for genomic surveillance.
South Africa conducts genome sequencing on only a small proportion of total samples collected each week. The NICD did not give a total number of confirmed cases of Omicron infection.
"(The) mutation profile and epidemiological picture suggests Omicron is able to get around some of our immune protection (to cause infection) but the protection against severe disease and death from vaccines should be less affected," the latest report from the surveillance network said.
The earliest sample in which the variant was detected was collected on November 8 in Gauteng.
Since then, it has been detected in Eastern Cape, KwaZulu Natal, Mpumalanga and Western Cape.
The Delta variant drove South Africa's third wave of infections, which peaked at more than 26,000 cases per day in early July.
Since the start of the pandemic, the country has reported close to 3 million infections and over 89,000 deaths, the most on the African continent.