The Omicron variant has propelled a sharp rise in coronavirus cases in South Africa in recent weeks, health officials told parliament Wednesday, calling the situation "worrying".
There had been an "exponential increase" over the past two weeks, from a weekly average of around 300 new cases per day to 1,000 last week and most recently 3,500, said Michelle Groome of the National Institute for Communicable Diseases (NICD).
"The degree of increase is worrying," Groome added.
Late Wednesday, the NICD said 8,561 new cases were reported nationwide over 24 hours, up from almost 4,400 the day before and 2,300 on Monday.
South Africa was the first country to detect Omicron, a new variant of the coronavirus with a high number of mutations, reporting its first cases on November 25 to the World Health Organization.
In Gauteng, South Africa's most populous and most affected province which includes the city of Johannesburg, the rate of tests coming back positive rose to 27 percent on Wednesday.
Groome said the figures represented "very early stages of the fourth wave" of COVID-19 infections.
The "rapidly increasing number of new daily cases" was "fueled by the variant" dubbed Omicron, she added.
After first spreading through younger people aged 10-29, many celebrating the end of the school year in the southern hemisphere's spring, "it is starting to move to older age groups".
South Africa is the country hit hardest on the continent by the pandemic with almost 3 million cases.
That figure was "underestimated, far below the true number of real cases," Groome said, highlighting that "some (people) are asymptomatic" and others "for all sorts of reasons may not test".