The coronavirus storm has arrived in South Africa, but in the overflowing COVID-19 wards the sound is less of a roar than a rasp. Oxygen is already low in hospitals at the new epicenter of the country’s outbreak, Gauteng province, home to the power centers of Johannesburg and the capital, Pretoria. Health Minister Zweli Mkhize, visiting a hospital Friday, said authorities are working with industry to address the strained oxygen supply and divert more to health facilities.