More than half of people in Europe could be infected with the coronavirus in the next six to eight weeks, the World Health Organisation warned on Tuesday, amid “a new west-to-east tidal wave sweeping across the region”.

“The region saw over seven million cases of Covid-19 in the first week of 2022, more than doubling over a two-week period,” Hans Kluge, the agency’s regional director for Europe, said at a news conference.

In a remarkable demonstration of how fast the virus is spreading, he said that 26 countries in the European region were reporting that more than 1 per cent of their populations were catching the virus every week.

Although the WHO has cautioned for months that booster shots could worsen vaccine equity around the world, Dr Kluge said that they would play an essential role in protecting the most vulnerable people from severe disease and should also be used to protect health workers and other essential employees, including teachers.

He said that a wave of infection spreading from west to east was starting to hit nations with lower vaccination rates in the Balkans and eastern Europe.

Despite the widespread level of infection, Dr Kluge said that coronavirus vaccines remained remarkably effective at preventing severe illness and death. He cited data from Denmark showing that the number of unvaccinated people who needed hospital care in the latest wave was sixfold higher than among vaccinated people.

“For countries not yet hit with the omicron surge, there is a closing window to act now and plan for contingencies,” he said.

One of the central struggles of governments across Europe has been trying to keep schools open, and Dr Kluge described those efforts as essential.

“Schools should be the last places to close and the first to reopen,” he said.

“The numbers of infected people are going to be so high in many places that schools in many countries are going to be unable to keep all classes open” because of illness and staff shortages, he added. An example of that pressure could be seen this week in France, where 10,452 classes were cancelled on Monday, according to the French government.

Prime Minister Jean Castex said that, going forward, schoolchildren in the country would be allowed to do self-tests instead of a PCR test if one of their classmates tested positive, in an attempt to keep the education system functioning.