NAIROBI, Dec 9 (Reuters) - South Africa, where the Omicron coronavirus variant is driving a fourth wave of COVID-19 infections, has seen a 255% increase in infections in the past seven days, but only 6% of intensive care beds are occupied by COVID-19 patients, WHO Africa official Thierno Balde said on Thursday. Balde"s comments at a news conference follow early anecdotal accounts by South African doctors and researchers that Omicron is causing mainly mild disease. read more