First cases of local Omicron infections were reported Thursday and Friday in the United States and Australia, increasing concerns over the new coronavirus variant, which is already spreading fast in South Africa and could become dominant in Europe.
The discovery of the new strain, first reported to the World Health Organization by South Africa on November 24, has spread worldwide rapidly, as the EU health agency warned it could cause more than half of Europe's Covid cases in the "next few months."
More than two dozen countries and territories have now detected cases, including India on Thursday, one of the countries hardest-hit by the coronavirus pandemic since it first emerged nearly two years ago.
The WHO has said it could take weeks to discover if Omicron is more transmissible, and whether it causes more severe disease -- as well as how effective current treatments and vaccines are against it.
But a new preliminary study by South African researchers suggests it is three times more likely to cause reinfections compared to the Delta or Beta strains, the first epidemiological evidence about Omicron's ability to evade immunity from prior infection.
The paper, which has not yet been peer reviewed, was praised by Michael Head, a scientist at the University of Southampton.
"This analysis does look very concerning, with immunity from previous infections being relatively easily bypassed," he said.
The variant is already showing signs of community spread, with 10 cases so far confirmed in the United States, including five in New York announced late Thursday, one in Los Angeles county and one in Hawaii.
The Hawaii case and one in Minnesota both involved residents with no recent international travel history, signaling the strain is already circulating inside the country.
"This is a case of community spread," the Hawaii Health Department said.
The cases were reported just as US President Joe Biden outlined his plans to battle Covid-19 during the winter, with new testing requirements for travelers and a surge in vaccination efforts.
"It's a plan that I think should unite us," Biden said, urging political opponents to put aside their differences. All incoming travelers will need to test negative within a day before their flight, and rapid tests that currently cost $25 will be covered by insurance and distributed free to the uninsured.
Australia on Friday also reported a student with no history of foreign travel had tested positive for the variant. The case, detected in the country's largest city Sydney, comes despite a ban on non-citizens entering the country and restrictions on flights from southern Africa.
The variant's detection and spread represent a fresh challenge to global efforts to battle the pandemic, with several nations already reimposing restrictions many had hoped were a thing of the past.
In Germany, outgoing Chancellor Angela Merkel said large parts of public life would be "open only to those who have been vaccinated or recovered" from Covid-19.
The German parliament is due to vote on mandatory immunizations.
It is not yet clear when the latest measures will go into effect, but the plans include a blanket ban on entering bars, restaurants and cinemas for anyone who is unvaccinated or not recovered from Covid, according to a document signed by leaders.
The agreement also includes new restrictions on large gatherings -- which would affect events such as Bundesliga football matches -- and the closure of nightclubs in areas with a weekly incidence rate above 350 infections per 100,000 people.
Fireworks will be banned on New Year's Eve to stop large crowds from gathering, according to North Rhine-Westphalia state premier Hendrik Wuest.
On Thursday, Norway introduced new anti-Covid measures in greater Oslo after a suspected cluster of Omicron cases emerged among dozens of vaccinated people who attended a Christmas dinner last week. So far, one Omicron case in the cluster has been confirmed.
Face masks will be mandatory in public transport, shopping centers, shops and taxis when social distancing is not possible. People will have to work from home if possible, and private indoor gatherings will be limited to 100 people, the government said.
Rising Delta infections had already seen European governments reintroduce mandatory mask-wearing, social distancing measures, curfews or lockdowns in a desperate attempt to limit hospitalizations, leaving businesses fearing another grim Christmas.
India has yet to impose new blanket international travel bans, but earlier this week, its health ministry ordered all inbound travelers from "countries at-risk" to undergo mandatory post-arrival Covid testing, along with the random testing of other international arrivals.
WHO chief Tedros Adhanom Ghebreyesus has warned of a "toxic mix" of low vaccination and testing rates creating a "recipe for breeding and amplifying variants."
Belgian Health Minister Frank Vandenbroucke spoke of "chaos" in Flemish schools as cases soared and the country's leading region Flanders called for new measures.
The United Nations said Thursday that the pandemic has pushed 20 million more people into poverty, estimating that 274 million people would need emergency assistance next year, up 17 percent on 2021, as economies suffer with Covid-19 restrictions.