In the UK, Boris Johnson is expected to outline plans to ease England’s Covid rules when he makes a statement on Plan B later on Wednesday.
Speaking during a news conference at the WHO’s Geneva headquarters, Dr Tedros said the Omicron variant had resulted in 18 million new infections across the world over the past week.
But he warned that while the variant may prove to be less severe on average, “the narrative that it is a mild disease is misleading,” he said.
“Make no mistake, Omicron is causing hospitalisations and deaths, and even the less severe cases are inundating health facilities.”
He warned leaders that “with the incredible growth of Omicron globally, new variants are likely to emerge, which is why tracking and assessment remain critical”.
“I remain particularly concerned about many countries that have low vaccination rates, as people are many times more at risk of severe illness and death if they are unvaccinated,” he added.
The WHO’s emergencies director, Dr Mike Ryan, also warned that Omicron’s increased transmissibility is likely to drive a rise in hospitalisations and deaths, especially in nations where fewer people are vaccinated.
“An exponential rise in cases, regardless of the severity of the individual variants, leads to inevitable increase in hospitalisations and deaths,” he said.
Europe reporting record case numbers
Coronavirus infections have surged across the continent since the Omicron variant was first identified at the end of November last year.
In Denmark, official data shows a record 33,493 new daily cases of Covid-19 on Tuesday, while health authorities in Italy recorded 228,179 new infections, up from 83,403 the previous day.
France meanwhile reported 464,769 new daily infections on Tuesday, more than four times higher than Monday’s figure of 102,144 and a daily record for the pandemic.
Infections have now climbed past a weekly average of more than 300,000 new cases per day.
It comes amid a furore over education, with France’s teachers’ unions calling for a second major strike this week to protest against the government’s Covid testing and isolation protocols, which they say are severely disrupting classes.
Many are calling on French education minister Jean-Michel Blanquer to resign after it emerged he had announced a strict Covid-testing protocol for schools while he was on holiday in Ibiza.
Early indications Omicron may have peaked in Europe
The data suggests the latest wave, caused by the Omicron variant, may have already peaked in some European countries.
In Ireland, new cases have started to fall in recent days, with health minister Stephen Donnelly telling the state broadcaster RTÉ that restrictions introduced over Christmas and the New Year period could be loosed by the end of the month.
Spanish government data has shown that new infections have started to fall for first time since the Omicron wave began two and a half months ago - although experts warned about reading too much into the data.
In the UK, daily case numbers are falling, with the total recorded over the past seven days down 38.9 per cent on the previous week.
Covid hospital admissions also appear to be starting to decrease, with the weekly figure down 2.9 per cent in the seven days up to 14 January, according to the latest figures.
It also saw a further 438 deaths within 28 days of a positive test - the highest figure since February 24, but experts cautioned death figures tend to be higher after weekends due to reporting delays.