More than half of the European population are expected to be infected with the omicron coronavirus variant within the next six to eight weeks, the World Health Organization’s top Europe official said on Tuesday.

Europe saw more than 7 million newly reported COVID-19 cases in the first week of 2022, more than doubling over a two-week period, the WHO’s Europe director Dr. Hans Kluge told a news briefing.

Dr. Hans Kluge said at a media briefing on Tuesday that 26 countries in its region reported that more than 1% of their populations are being infected with COVID-19 each week, warning there is now a closing window of opportunity for countries to prevent their health systems from being overwhelmed.

“At this rate, the Institute for Health Metrics and Evaluation forecasts that more than 50 percent of the population in the region will be infected with omicron in the next 6-8 weeks,” Kluge said.

Omicron moves faster and wider than any (previous) variant we have seen, he said. Kluge called for countries to mandate the use of masks indoors and to prioritize vaccination, including booster doses, of at-risk populations, including health workers and older people.

Kluge said he was greatly concerned that as omicron moves east across the European continent, the variant will take a much higher toll on countries with lower vaccination coverage rates.