Germany decided on Thursday to bar the unvaccinated from all but the most essential businesses and the United States was due to announce further travel curbs as countries around the globe scramble to keep out the Omicron variant of the coronavirus.
U.S. Treasury Secretary Janet Yellen said the variant showed the pandemic could be around for "some time," as countries including the United States, India and France reported their first cases.
In an interview with Reuters, Yellen said she hoped the pandemic would not completely stifle economic activity, adding that the U.S. stimulus at the start of the pandemic had helped fuel a very strong recovery.
The new measures agreed in Germany focus on the unvaccinated, who will only be allowed in essential businesses such as grocery stores and pharmacies, while legislation to make vaccination mandatory will be drafted for early next year.
"We have understood that the situation is very serious and that we want to take further measures in addition to those already taken," Chancellor Angela Merkel told a news conference.
A nationwide vaccination mandate could take effect from February 2022 after it is debated in the Bundestag and after guidance from Germany's Ethics Council, she said.
Eager to avoid derailing a fragile recovery of Europe's biggest economy, Germany kept businesses open to the almost 69% of the population that is fully vaccinated as well as those with proof of having recovered from the virus.
Much remains unknown about Omicron, which was first detected in southern Africa last month and has been spotted in at least two dozen countries, just as parts of Europe were already grappling with a wave of infections of the Delta variant.
But the European Union's public health agency said Omicron could be responsible for more than half of all COVID infections in Europe within a few months, lending weight to preliminary information about its high transmissibility.
In the United States, the Biden administration was expected to announce steps included extending requirements for travellers to wear masks through mid-March.
It will also require private health insurance companies to reimburse customers for at-home COVID-19 tests, a senior administration official said.
Biden is due to spell out the measures at 1840 GMT.
South Africa said it was seeing an increase in COVID-19 reinfections in patients contracting Omicron - with people who have already had the illness getting infected again - in a way that it did not see with other variants.
The first known U.S. case, announced late on Wednesday, was a fully vaccinated person in California who had travelled to South Africa. The two French cases, in the greater Paris region and in eastern France, were passengers arriving respectively from Nigeria and South Africa.
Global shares fell on Thursday, reversing gains from the previous session as a lack of information about Omicron left markets volatile, while crude oil futures extended losses.
Russia has imposed a two-week quarantine for travellers from some African countries including South Africa, the Interfax news agency said, quoting a senior official. Hong Kong extended a travel ban to more countries.
Amid all the new restrictions, Europe's largest budget airline, Ryanair, said it expected a challenging time at Christmas, although it was still optimistic about summer demand.
In the Netherlands, health authorities called for pre-flight COVID-19 tests for all travel from outside the European Union, after it turned out that most of the passengers who tested positive after arriving on two flights from South Africa on Nov. 26 had been vaccinated.
In France, the country's top scientific adviser, Jean-Francois Delfraissy, said the "true enemy" for now was still the more familiar Delta variant of the virus, spreading in a fifth wave.
Laboratory analysis of the antibody-based COVID-19 therapy GlaxoSmithKline is developing with U.S. partner Vir has indicated the drug is effective against Omicron, the British drugmaker said.