Dutch health officials said on Sunday that they had found at least 13 cases of the Omicron coronavirus variant among 61 infected passengers who had arrived in the Netherlands from South Africa on Friday. The new cases were a clear sign that the virus was crossing borders even as governments imposed new travel restrictions and flight bans.
Additional cases could emerge, as health officials were still examining test samples, said Hugo de Jonge, the country’s health minister, adding that the people who tested positive were isolating. The 61 passengers who had tested positive were among more than 500 who arrived on two separate flights.
A growing list of countries is scrambling to respond to the new, highly mutated version of the virus, which was first detected in Botswana and South Africa and which has sent ripples of panic through governments and markets. Health officials in Australia and Denmark on Sunday both confirmed cases of the Omicron variant in travelers recently arriving from southern Africa. Morocco said Sunday it would ban all incoming flights for at least two weeks beginning Monday amid concerns about Omicron, according to a government statement on state-run news media. The flight ban prevents both foreign nationals and Moroccan citizens from entering.
And British health officials said Sunday a third case had been detected in an individual who had spent time in Westminster, in central London. They said the case was linked to travel to southern Africa.
The World Health Organization warned on Friday that Omicron was a “variant of concern,” the most serious category the agency uses for such tracking, and said that its numerous genetic mutations could help it spread more quickly, even among vaccinated people.
Scientists cautioned that relatively little is known about the new variant, and that only a small number of confirmed cases have surfaced globally. Still, there are worries that Omicron could have spread more widely before scientists in South Africa discovered it last week, and the memories of the rampaging spread this year of the Delta variant have prompted new waves of travel restrictions, aimed primarily at southern African countries.
Britain, Italy, Belgium, the Netherlands and Israel are among the countries that have identified Omicron cases in recent days and imposed new travel restrictions. In a sign of how seriously the authorities in Europe, which is already battling a surge of coronavirus cases, are taking the new threat, officials in France on Friday also suspended arrivals from seven southern African countries even though the new variant had not yet been detected in France.
“It’s probably a question of hours, let’s be honest,” Olivier Véran, the health minister, told reporters on Sunday at a vaccination center in Paris. But he added that “new variant doesn’t necessarily mean new wave, or that the variant is more dangerous.”
“To be safe, we are acting as though this variant is potentially dangerous,” he said.
The European Union is restricting travel to and from seven countries in southern Africa — Botswana, Eswatini, Lesotho, Mozambique, Namibia, South Africa and Zimbabwe — while the United States and South Korea have targeted those countries and Malawi. Britain has restricted travel with those eight nations and Angola, Mozambique and Zambia.
Israel announced the world’s strictest ban to date, sealing its borders to all foreigners for 14 days after one case was confirmed in the country.
Scientists were careful to note that the extent of the threat from Omicron remained unclear, and that existing vaccines were likely to protect against it. Although some variants of concern, like Delta, have lived up to initial worries, others have had a more limited impact.
Some experts, including the W.H.O., said that the rush to reintroduce travel bans and border closures was premature and would unfairly punish African countries that have already suffered from delayed and insufficient vaccine supplies caused in large part by Western countries hoarding doses.
In Australia, officials said that Omicron was detected in two travelers who flew into Sydney on Saturday evening on a Qatar Airways flight from Doha. They were asymptomatic and fully vaccinated, according to a statement from the health authority in New South Wales State. The travelers were placed into quarantine.
In Denmark, officials said that Omicron was detected in two travelers who had recently arrived from South Africa. Both are in isolation, and close contacts are being tracked down, according to a statement by the State Serum Institute, Denmark’s infectious disease authority.
“This was expected, and our strategy is therefore to continue intensive surveillance of the infection in the country,” said Henrik Ullum, the institute’s chief executive. “We want to accelerate the process so that…