Omicron, but the new variant’s spread has led to warnings that it could cause more than half of Europe’s Covid cases in the next few months.

The new variant could also slow global economic recovery, just as the Delta strain did, International Monetary Fund chief Kristalina Georgieva said on Friday.

“Even before the arrival of this new variant, we were concerned that the recovery, while it continues, is losing somewhat momentum,” she said.

“A new variant that may spread very rapidly can dent confidence.”

A preliminary study by researchers in South Africa, where the variant was first reported on November 24, suggests it is three times more likely to cause reinfections compared to the Delta or Beta strains.

The emergence of Omicron was the “ultimate evidence” of the danger of unequal global vaccination rates, Red Cross head Francesca Rocca said.

South African doctors said there had been a spike in children under 5 admitted to hospital since Omicron emerged, but stressed it was too early to know if young children were particularly susceptible.

“The incidence in those underfives is now second-highest, and second only to the incidence in those over 60,” said Wassila Jassat from the National Institute for Communicable Diseases.

In the US, two cases involved residents with no recent international travel history — showing

Omicron is already circulating inside the country.

“This is a case of community spread,” the Hawaii Health Department said.

US President Joe Biden on Thursday unveiled his plans to battle Covid-19 during the winter, with new testing requirements for travelers and a surge in vaccination efforts.

All incoming travelers will need to test negative within a day of their flights, and rapid tests that cost $25 will be covered by insurance and distributed free to the uninsured.

Australia on Friday reported three students in Sydney had tested positive for the variant, despite a ban on non-citizens entering the country and restrictions on flights from southern Africa, with multiple countries rushing to limit travel from the region in the past week.