Half of people in Europe will have caught the Omicron variant of Covid-19 within the next six to eight weeks, it has been claimed.
Dr Hans Kluge, the World Health Organisation's Europe director, said a "west-to-east tidal wave" of the strain was sweeping across the continent on top of a surge in the Delta variant.
He told a media briefing on Tuesday that 26 countries in western Europe reported that more than 1% of their populations are being infected with Covid-19 each week and warned there is a "closing window of opportunity" for countries to prevent their health systems from being overwhelmed.
Read more: Two top doctors explain what's really happening with Covid in Welsh hospitals
He cited estimates from the Institute of Health Metrics at the University of Washington that projected half of the population in western Europe will be infected with Covid-19 in the next six to eight weeks.
"Omicron moves faster and wider than any (previous) variant we have seen," he said.
"Today the variant represents a new west-to-east tidal wave sweeping across the region on top of the Delta surge that all countries were managing until late 2021."
He said European and Central Asian countries remained under "intense pressure" as the virus spread from western countries into the Balkans.
"How each country now responds must be informed by its epidemiological situation, available resources, vaccination uptake status, and socio-economic context", he added.
Dr Kluge called for countries to mandate the use of masks indoors and to prioritise vaccination, including booster doses, of at-risk populations including health workers and older people.
He added he was greatly concerned that as Omicron moves east across Europe the variant will take a much higher toll on countries with lower vaccination coverage rates.
In Denmark he noted the hospital admission rate was six times higher in people who were not vaccinated compared with those who had been immunised.
On Monday the UK reported a further 142,224 confirmed cases of the virus and 77 deaths. In Wales 2,176 new cases were reported on Tuesday and four new deaths. Covid hospital admissions are also on the rise. You can read the latest bulletin here.
To get the latest WalesOnline newsletters emailed to you directly for free click here.
