A "tsunami" of Omicron and Delta Covid-19 cases will pile pressure on health systems already being stretched to their limits, the World Health Organization warned on Wednesday.
The WHO said the Delta and Omicron variants of concern were "twin threats" that were driving new case numbers to record highs, leading to spikes in hospitalisations and deaths.
The WHO said new global cases had risen by 11 per cent last week, while the United States and France both registered record daily case numbers on Wednesday.
"I am highly concerned that Omicron, being more transmissible, circulating at the same time as Delta, is leading to a tsunami of cases," WHO chief Tedros Adhanom Ghebreyesus told a press conference.
"This is and will continue to put immense pressure on exhausted health workers, and health systems on the brink of collapse."
He said the pressure on health systems was not only due to new coronavirus patients, but also large numbers of health workers falling ill with Covid.
"The unvaccinated are many times more at risk of dying from either variant," he added.