Countries across Europe considered new curbs on movement on Tuesday as US President Joe Biden called on military medics to support hospitals and fight the omicron variant that has swept the world days before the second Christmas of the pandemic.

Omicron infections are multiplying across Europe, the US and Asia, including in Japan, where a single cluster of Covid-19 cases at a military base has grown to at least 180.

“We can see another storm coming,” said Hans Kluge, the World Health Organisation’s European head, warning European countries to brace for a “significant surge” in Covid-19.

Biden struck a dire tone about the risks to the one in four American adults still unvaccinated. He will lay out new measures on testing later, a senior administration official said. The steps include activating some 1,000 military medical personnel to support hospitals already being overwhelmed.

Germany, Scotland, Ireland, the Netherlands and South Korea are among countries to have reimposed partial or full lockdowns or other social distancing measures in recent days.

Nicola Sturgeon, first minister of Scotland — part of the UK but with devolved responsibilities for health — set out plans for further restrictions on big public events, including sports fixtures, for three weeks after Christmas.

“It will also mean unfortunately that large scale Hogmanay celebrations, including that planned here in our capital city (Edinburgh), will not proceed,” she said, referring to traditional Scottish New Year parties.

New Zealand Covid-19 response minister Chris Hipkins said his country, which imposed some of the world’s toughest Covid-19 measures, was delaying the start of a staggered reopening of its border until the end of February.

“All of the evidence so far points to Omicron being the most transmissible Covid-19 variant yet,” he said.

Germany’s Robert Koch Institute for infectious diseases on Tuesday urged “maximum contact restrictions” be imposed at once.

Federal and state leaders will decide on new measures, which were likely to include contact restrictions even for the vaccinated and those who have recovered from an infection, but a nationwide lockdown seemed to be off the cards.

WHO’s Kluge told a news conference in Vienna that within weeks omicron would dominate in more countries of the region, “pushing already stretched health systems further to the brink”.

The Sun newspaper reported that British Prime Minister Boris Johnson was expected to announce in the next 48 hours whether he will impose “circuit-breaker” restrictions in England.

These would limit pubs and restaurants to outdoor service only and ban indoor mixing between households.

Finance minister Rishi Sunak announced 1 billion pounds ($1.3 billion) of extra support for businesses hit hardest by Omicron, which is hammering the hospitality sector and other businesses.