Passengers disembark from a plane on their arrival in Polokwani, South Africa, on March 14, 2020 after being repatriated from Wuhan, China . (AP Photo)

(AP) -- South Africa will revoke nearly 10,000 visas issued this year to people from China and Iran, and visas will now be required for other high-risk countries that had been visa-free, including Italy and the United States.

Health Minister Zweli Mkhize says a lockdown might be necessary if tough new measures announced Sunday, including travel restrictions and school closings, don't work. He warns of a high risk of internal virus transmission with "the problem of inequality in our society."

South Africans worry about the spread of the virus to crowded townships or public transport.

Confirmed virus cases have doubled every two days over 10 days to 61, a rate he called "explosive."

Elsewhere, Africa's second most populous nation, Ethiopia, has suspended schools, sporting events and other large gatherings for 15 days.