Two senior ministers in the cabinet of South African President Cyril Ramaphosa are in self-isolation after testing positive for COVID-19.

The number of coronavirus infections in the country soared to 4,373 on Tuesday night from Monday's high of 2,273.

Minister of Social Development Lindiwe Zulu's positive result came in the wake of the detection of the new coronavirus variant Omicron, which the World Health Organisation has declared a “variant of concern”.

“The Minister has immediately started isolating and recovering at home and will continue carrying out her duties without disruptions,” her office said in a statement.

“It all started with a scratchy throat and I didn't suspect anything, but when it persisted, I took the COVID-19 test yesterday and received the results this morning. I am feeling well and I can attribute this to the fact that the virus found me fully vaccinated,” Zulu said.

Home Affairs Minister Aaron Motsoaledi also tested COVID-19 positive and went into self-isolation.

Minister in the Presidency Mondli Gungubele said in a statement that the Home Affairs Minister is in good health and self-isolating.

Zulu urged South Africans who had not yet been vaccinated to take advantage of the Vooma Vaccination Weekend campaign from December 3 to 5.

“As President Ramaphosa emphasised, vaccination is the most powerful tool we have and it is not too late to get vaccinated before the fourth wave hits us hard,” she said.

Authorities are expecting a rush for vaccinations as the media hype around the Omicron variant decreases the vaccine hesitancy that has been increasing for the past few weeks, hampering attempts to reach targets set for vaccination.