A potent coronavirus variant originating in South Africa has been detected for the first time in the United States in two South Carolina patients, US health officials said on Thursday.<br /><br />Medical experts said arrival of the so-called South African variant presented an alarming new challenge in efforts to contain a raging pandemic that has claimed at least 430,000 American lives in 11 months, as authorities struggle to launch the largest mass-vaccination campaign in US history.
