South Africa has given 44% of its adult population at least one dose of COVID-19 vaccine, more than many African countries.

South Africa's health minister said on Friday that the government believed that vaccines and high levels of prior COVID-19 infection were helping to keep disease milder in a wave driven by the Omicron variant.

There have been early anecdotal accounts suggesting that the Omicron variant driving the fourth wave, which saw the country report a record number of daily infections earlier this week, is causing less severe illness than previous variants in South Africa but scientists say it is too early to draw firm conclusions.

"We believe that it might not necessarily just be that Omicron is less virulent, but ... coverage of vaccination (and) ... natural immunity of people who have already had contact with the virus is also adding to the protection," Health Minister Joe Phaahla told a news conference. "That's why we are seeing mild illness."

South Africa has given 44% of its adult population at least one dose of COVID-19 vaccine, more than many African countries but well short of the government's year-end target. But among the over-50s vaccination coverage levels are over 60%.

Addressing the same news conference, Michelle Groome from the National Institute for Communicable Diseases said there had been an uptick in COVID-19 hospital admissions and deaths.

"Starting to see a slight increase in deaths nationally, but once again this level is very much lower even than the baseline period we were seeing between the second and third waves," Groome said.

Phaahla said early indications were that infections might have peaked in the most populated Gauteng province, where cases initially surged. He added that in the coming week the health department would report back to the National Coronavirus Command Council on whether COVID-19 restrictions should be adjusted.