The Omicron variant of Covid-19 is leading to hospitalisation and it also kills people across the globe and should not be dismissed as mild, the World Health Organization insisted on Thursday. WHO chief Tedros Adhanom Ghebreyesus said the record numbers of people catching the new variant — which is rapidly out-competing the  previously-dominant Delta variant in many countries — meant hospitals were being overwhelmed. “While Omicron does appear to be less severe compared to Delta, especially in those vaccinated, it does not mean it should be categorised as mild,” Tedros told a press conference. “Just like previous variants, Omicron is hospitalising people and it is killing people,” he explained. “In fact, the tsunami of cases is so huge and quick, that it is overwhelming health systems around the world.” Just under 9.5 million new Covid-19 cases were reported to the WHO last week — a record, up 71 percent on the week before. But even this was an underestimate, Tedros said, as it did not reflect the backlog of testing around the Christmas-New Year holidays, positive self-tests not registered, and overburdened surveillance systems missing cases, Tedros added.