The new coronavirus variant Omicron has now become dominant in South Africa and is driving a sharp increase in new infections, health officials say.
Some 8,500 new Covid infections were registered in the latest daily figures.
That is almost double the 4,300 cases confirmed the previous day.
By contrast, daily infections were averaging between 200 and 300 in mid-November, a top South African scientist told the BBC.
Omicron has now been detected in at least 24 countries around the world, according to the World Health Organization (WHO).
The full picture in South Africa will not become clear until "people get so sick that they need to go to hospital" which is generally "three, four weeks later," says Prof Salim Abdool Karim of the Africa Task Force for Coronavirus.