Dec 22 (Reuters) - A new South African study, along with data on hospitalisations and deaths in the country"s fourth wave of COVID infections, suggest that the risk of severe disease is lower with Omicron than with previous variants, a top scientist said on Wednesday. "In South Africa, this is the epidemiology: Omicron is behaving in a way that is less severe," said Professor Cheryl Cohen of the National Institute for Communicable Diseases (NICD), one of the authors of the new study. read more "Compellingly, together our data really suggest a positive story of a reduced severity of Omicron compared to other variants," she said during a news conference by a group of NICD scientists.