Ewen Callaway & Heidi Ledford South Africa is dealing with a large uptick in COVID cases, driven by a new, heavily mutated variant called Omicron. Credit: Guillem Sartorio/AFP/Getty Barely a week has elapsed since scientists in Botswana and South Africa alerted the world to a fast-spreading new SARS-CoV-2 variant now known as Omicron. Researchers worldwide are racing to...
