BERLIN, Dec 23 (Reuters) - Germany"s Robert Koch Institute for infectious disease confirmed the country"s first death due to the Omicron variant of the coronavirus on Thursday. The person was between the age of 60 and 79, the institute said. There were 810 new Omicron cases reported, bringing the total number of cases with the more contagious variant to 3,198. The only cases counted are those that are detected by a whole genome sequencing or a diagnostic suspicion based on a variant-specific PCR test.