The World Health Organization warned on Monday that global risks posed by the new Omicron variant of the coronavirus were “very high,” as countries around the world rushed to defend against its spread with a cascade of border closures and travel restrictions that recalled the earliest days of the pandemic.
Scotland and Portugal identified new cases of the highly mutated variant, and Japan joined Israel and Morocco in banning all foreign visitors, even as scientists cautioned that the extent of the threat posed by Omicron remained unknown — and as the patchwork of travel measures were so far proving unable to stop its spread.
Many of the restrictions aimed at corralling Omicron, which was first identified last week by researchers in South Africa, were aimed at travelers from southern Africa, drawing accusations that Western countries were discriminating against a region that has already been set back by vaccine shortages caused by rich nations hoarding doses.
In a technical briefing note to member countries, the W.H.O. urged national authorities to step up surveillance, testing and vaccinations, reinforcing the key findings that led its technical advisers on Friday to label Omicron a “variant of concern.”
The agency warned that the variant’s “high number of mutations” — including up to 32 variations in the spike protein — meant that “there could be future surges of Covid-19, which could have severe consequences.”
Experts say that while the variant may be more transmissible than prior versions of the virus, existing vaccines are likely to offer protection from severe illness and death, although some countries, including Britain, were preparing to expand booster programs to protect more people.
The agency stressed the need for countries to accelerate vaccinations against Covid as rapidly as possible, particularly for vulnerable populations and for those who are unvaccinated or not fully vaccinated. It also called on health authorities to strengthen surveillance and field investigations, including community testing, to better determine Omicron’s characteristics.
The recommendation underscored that the steps taken by some countries to wind down testing and tracing capacity in recent months — as the pandemic appeared to be receding thanks to rising vaccination rates — are moving in the wrong direction.
“Testing and tracing remains fundamental to managing this pandemic and really understanding what you’re dealing with,” said Margaret Harris, a spokeswoman for the agency. “We’re asking all countries to really look for this variant, to look if people who have got it are ending up in hospital and if people who are fully vaccinated are ending up in hospital.”
The briefing note adds that P.C.R. tests are an efficient tool for detecting the new variant because they do not require as long a wait for an outcome as genetic sequencing tests that require laboratory capacity not available in all countries.
“It’s very good news,” Ms. Harris said. “You can much more quickly spot who’s got it.”
But while the agency had previously cautioned against imposing travel bans, the briefing note took a more flexible line, calling for a “risk-based approach” to travel restrictions that could include modified testing and quarantine requirements. The agency said it would issue more detailed travel advice in the coming days.
Japan on Monday joined Israel and Morocco in barring all foreign travelers, and Australia delayed reopening its borders for two weeks, as more countries sealed themselves off in response to the new Omicron variant of the coronavirus.
The Japanese prime minister, Fumio Kishida, said that Japan would reverse a move earlier this month to reopen its borders to short-term business travelers and international students. Japan, the world’s third-largest economy, has been closed to tourists since early in the pandemic, a policy it has maintained even as other wealthy nations reopened to vaccinated visitors.
Some countries proceeded with their plans to reopen on Monday, like Singapore and Malaysia, which opened their land border. South Korea, on the other hand, announced that it was delaying any loosening of social distancing restrictions.
Australia said on Monday that it would delay by two weeks its plan to reopen its borders to international students, skilled migrants and travelers from Japan and South Korea. The country said it would use the delay, to Dec. 15, to study whether the Omicron variant is more dangerous than the Delta variant, which raced across the world earlier this year.
Israel reopened to vaccinated tourists only four weeks ago.
Hours after Israel announced its blanket ban over the weekend, Morocco said on Sunday that it would deny entry to all travelers, even Moroccan citizens, for two weeks beginning Monday. The country is banning all incoming and outgoing flights over the two-week period.
The moves by Japan, Israel and Morocco stood in contrast to those in places like the United States, Britain, Canada and the European Union, which have all announced bans on travelers only from southern Africa.
Meanwhile, Indonesia on Monday joined a small but growing list of countries to bar travel with Hong Kong as well as the southern African region. Hong Kong detected two cases of Omicron on Thursday, prompting India, Pakistan and other nations to impose a travel ban.
The travel bans have triggered resentment among Africans who believed that the continent was yet again bearing the brunt of panicked policies from Western countries, which had failed to deliver vaccines and the resources needed to administer them.
In Japan, all foreign travelers except those who are residents of the country will be barred from entering starting at midnight on Monday.
In Israel, all foreign nationals will be banned from entering for at least 14 days, except for urgent humanitarian cases to be approved by a special exceptions committee. Returning vaccinated Israelis will be tested upon landing and must self-quarantine for three days, pending results of another P.C.R. test. Unvaccinated Israelis will have to self-quarantine for seven days.
Israelis returning from countries classified as “red,” with high risk of infection, including most African countries, must enter a quarantine hotel until they receive a negative result from the airport test, then transfer to home quarantine (until they get a 7-day P.C.R. test result).
Ran Balicer, the chairman of an expert panel that advises the Israeli government on Covid-19 response, said the decision was temporary and was taken out of prudence.
Japan has yet to report any cases of the new variant, though it is studying a case involving a traveler from Namibia. Israel has identified at least one confirmed case of Omicron so far — a woman who arrived from Malawi — and testing has provided indications of several more likely cases in the country.
Aida Alami contributed reporting from Morocco, and Muktita Suhartono from Indonesia.
Officials in Scotland confirmed on Monday that six cases of the Omicron variant of the coronavirus had been recorded in the country and that some of those infected had not traveled recently, suggesting that there was community transmission. But they said there was no evidence that the transmission was “sustained or widespread.”
All of the infected individuals are in isolation and none have been hospitalized, said Scotland’s first minister, Nicola Sturgeon, who described the emergence of the highly mutated Omicron variant as the “most challenging development of the pandemic for quite some time.”
At an emergency news conference, Ms. Sturgeon said that she had asked Prime Minister Boris Johnson of Britain to convene a meeting of Britain’s top emergency committee, insisting that the moment called for “collective, national vigilance.”
In a joint letter to Mr. Johnson, she and the first minister of Wales urged tougher rules for travelers entering the United Kingdom: “We need to work collectively — and effectively — as four nations to take all reasonable steps to control the ingress of the virus to the country and then to limit its spread.”
Four cases have been identified in the Lanarkshire area and two in the Greater Glasgow and Clyde area, officials said. Health officials had not yet determined whether the variant had arrived in Scotland from overseas. The country’s health agency and local health protection teams are carrying out contact tracing to establish the origin of the cases, as well as identify people who might have been exposed.
Ms. Sturgeon said there was no evidence yet that any of the six confirmed cases in Scotland had links to the United Nations climate summit, which took place in Glasgow this month. If that were the case, she said, “I think our surveillance efforts might be showing more cases.”
Still, Ms. Sturgeon said, the event, which drew participants from around the world, had not been ruled out as the source of the variant in Scotland.
The first minister urged the public to “use this as an opportunity to up compliance with all the restrictions” in place. She added that further restrictions on regional travel in the lead-up to Christmas were not planned, but warned that could change.
“I still hope, really fervently hope, to be having a normal Christmas with my family,” she said. “Can I say that with 100 percent certainty? No, but that’s what I hope, and that’s what I think we should all be hopeful for.”
President Biden will give an update on the U.S. response to the Omicron variant on Monday, the White House said in a statement on Sunday evening, as top federal health officials urged unvaccinated Americans on get their shots and eligible adults to seek out boosters.
Appearing on morning talk shows on Sunday, Dr. Francis Collins, director of the National Institutes of Health, cautioned Americans that the emergence of Omicron and the uncertainty that surrounds it are reminders that the pandemic is far from over.
While the variant has yet to be detected in the United States, maintaining vigilance and safeguarding public health through inoculations, masking indoors and distancing, remains critical, he said.
“I know, America, you’re really tired about hearing those things, but the virus is not tired of us,” Dr. Collins said. “And it’s shape-shifting itself.”
The White House said that President Biden met on Sunday with members of his Covid response team, including Dr. Anthony S. Fauci, the nation’s top infectious disease expert. With much still unknown about the Omicron variant, Dr. Fauci told the president that it would take approximately two more weeks to learn more about its transmissibility and severity, but said that “he continues to believe that existing vaccines are likely to provide a degree of protection against severe cases of Covid,” the White House said.
Dr. Collins stressed that inoculation remains the first line of defense, saying that there are “good reasons” to believe, based on previous variants, that current vaccines will provide sufficient protection.
“Please, Americans, if you’re one of those folks who’s sort of waiting to see, this would be a great time to sign up, get your booster,” Dr. Collins said on Fox. “Or if you haven’t been vaccinated already, get started.”
He also underlined other critical mitigation efforts, including indoor masking when around unvaccinated individuals and maintaining social distance, in slowing the spread.
Dr. Fauci delivered a similar message, sending a “clarion call” for vaccinations and boosters. It is inevitable that the variant, which has already been detected in several countries, will surface in the United States, Dr. Fauci said.
“The question is, will we be prepared for it?” Dr. Fauci said on ABC’s “This Week” on Sunday morning. “And the preparation that we have ongoing for what we’re doing now with the Delta variant just needs to be revved up.”
Portugal on Monday said it had identified 13 cases of the Omicron variant of the coronavirus, all tied to Belenenses, a soccer club that was forced to take part in a top-flight game over the weekend that was abandoned while in progress.
The country’s national health institute said that the 13 people were isolating and that they were all players or staff members of Belenenses, which fielded a depleted team of only nine players against Benfica on Saturday after reporting a coronavirus outbreak.
The institute also confirmed that one of the 13 people was a player who had recently returned to Portugal from South Africa, whose scientists helped identify Omicron. Benfica’s players will be tested for the virus, the country’s general health director, Graça Freitas, told the local TSF radio station.
Before the game on Saturday, as many as 17 players and staff members of the Belenenses club tested positive for the virus, although it was unclear at the time whether those cases involved the new variant. The Belenenses players sought to have the game canceled, but officials reportedly told them that it had to go on.
Separately, Portugal’s health authorities said they were tracing more than 200 passengers who had arrived in Portugal on Saturday from Maputo, Mozambique. At least two people on the flight had tested positive for the virus, but the authorities said it was too early to confirm whether these were Omicron cases.
Portugal on Monday began suspending all flights to and from Mozambique, which is a former Portuguese colony and shares a border with South Africa, over concerns about the new variant.
Even before concerns about the new Omicron variant arose, China had refused calls to loosen its border restrictions, which are among the strictest in the world.
Now Chinese researchers are offering data to support the government’s decision to maintain its extreme “zero Covid” strategy.
A recent study published on the country’s Center for Disease Control and Prevention website found that China could face more than 630,000 coronavirus cases a day if it dropped its zero-tolerance prevention measures and lifted curbs on travel, in the way that some Western countries have.
That would be more than five times as many as the total number of cases reported in China, which has a population of 1.4 billion, in the years since the virus first emerged in the central Chinese city of Wuhan, according to a New York Times database. Such an outbreak would put a huge strain on the country’s resources, including its hospital system, said the report, which was published before the World Health Organization labeled Omicron a “variant of concern.”
The authors of the report, who are scholars at Peking University in Beijing, wrote that the findings “raised a clear warning” that the country was not ready to open up.
“More efficient vaccinations or more specific treatment, preferably the combination of both, are needed before entry-exit quarantine measures and other Covid-19 response strategies in China can be safely lifted,” they wrote.
While China has vaccinated more than 75 percent of its population, questions have been raised about the efficacy of the country’s homegrown vaccines.
The Beijing government has staked much of its political legitimacy on controlling the virus better than other countries. The strategy, so far, has worked: China has reported fewer than 5,000 deaths since the pandemic began and has managed to quickly tame sporadic outbreaks through severe, and sometimes impractical, measures. On Monday, China reported just 21 locally transmitted cases, most of which were reported in the northern region of Inner Mongolia.
While some critics have warned that China’s approach could be unsustainable and counterproductive, growing concerns about the new Omicron variant now make it even more unlikely that Beijing will ease its restrictions, which include at least two weeks of mandatory quarantine for visitors as well as snap lockdowns and mass testing campaigns in areas where the virus is detected.
Dr. Zhang Wenhong, one of China’s top infectious disease experts, said on Sunday that the country’s comprehensive approach to fighting the virus made it well placed to confront the evolving threat.
“If we can cope with the Delta variant, we can also cope with Omicron,” Dr. Zhang wrote on Weibo, a popular Chinese social media platform.
A woman sent a quarantine hotel in Queensland, Australia, up in flames by lighting a fire under a bed in her room, according to police, triggering the evacuation of the building’s 163 occupants.
Police charged the 31-year-old woman, who was quarantining in the Pacific Hotel in the city of Cairns with her two children, with arson on Sunday.
The fire was started at about 7 a.m. on Sunday in the woman’s room on the top floor of the hotel in far north Queensland, police said. It then spread to neighboring rooms.
The hotel was quickly evacuated, and there were no injuries, said Chris Hodgman, the Queensland Police acting chief superintendent, on Sunday afternoon. But the hotel had suffered “significant damage,” he said, and the residents needed to be moved to another quarantine facility.
Photos and videos posted to social media showed flames and thick smoke pouring out of two rooms on the hotel’s 11th floor.
Her two children, with whom she had been occupying the room for a few days after arriving from another state in the country, were being looked after by police, he added.
Authorities charged the woman with one count of arson and another of willful damage. She was expected to appear in a local court on Monday.
Anyone who arrives in Queensland from another state or overseas must quarantine for 14 days under the state’s pandemic borer restrictions. Those who have a house that fits government criteria around ventilation may undergo home quarantine, but those who do not must quarantine in a designated hotel and foot the bill themselves.
The incident comes as rallies against pandemic measures continue to ramp up around Australia. On Saturday, police estimated that 20,000 people took to the streets of Melbourne to protest the state government’s plans to introduce a bill that would extend its powers to impose pandemic restrictions. The previous weekend, thousands in the country’s state capitals rallied against vaccination requirements and coronavirus restrictions.
On Monday, Australia reported a third case of the Omicron coronavirus variant, in a traveler from South Africa quarantining in the Northern Territory. Two cases were discovered in travelers quarantining in New South Wales on Sunday.
As nations severed air links from southern Africa amid fears of another global surge of the coronavirus, scientists scrambled on Sunday to gather data on the new Omicron variant, its capabilities and — perhaps most important — how effectively the current vaccines will protect against it.
The early findings are a mixed picture. The variant may be more transmissible and better able to evade the body’s immune responses, both to vaccination and to natural infection, than prior versions of the virus, experts said in interviews.
The vaccines may well continue to ward off severe illness and death, although booster doses may be needed to protect most people. Still, the makers of the two most effective vaccines, Pfizer-BioNTech and Moderna, are preparing to reformulate their shots if necessary.
“We really need to be vigilant about this new variant and preparing for it,” said Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle.
Even as scientists began vigorous scrutiny of the new variant, countries around the world curtailed travel to and from nations in southern Africa, where Omicron was first identified. Despite the restrictions, the virus has been found in a half-dozen European countries, including the United Kingdom, as well as Australia, Israel and Hong Kong.
Already, Omicron accounts for most of the 2,300 new daily cases in the province of Gauteng, South Africa, President Cyril Ramaphosa announced on Sunday. Nationally, new infections have more than tripled in the past week, and test positivity has increased to 9 percent from 2 percent.
Scientists have reacted more quickly to Omicron than to any other variant. In just 36 hours from the first signs of trouble in South Africa on Tuesday, researchers analyzed samples from 100 infected patients, collated the data and alerted the world, said Tulio de Oliveira, a geneticist at the Nelson R. Mandela School of Medicine in Durban.
Within an hour of the first alarm, scientists in South Africa also rushed to test Covid vaccines against the new variant. Now, dozens of teams worldwide — including researchers at Pfizer-BioNTech and Moderna — have joined the chase.
They won’t know the results for two weeks, at the earliest. But the mutations that Omicron carries suggest that the vaccines most likely will be less effective, to some unknown degree, than they were against any previous variant.
The discovery the Omicron variant comes at a delicate moment for an airline industry that was just starting to see a rebound.
The question is whether the new coronavirus variant will deter travelers, as the Delta variant did this summer.
Several nations, including the United States, have banned visitors from South Africa and a handful of neighboring countries. Japan, Morocco and Israel have barred all incoming foreign visitors, while the Philippines has banned visitors from southern Africa and several European countries.
The international travel recovery has been slower than it has been in the United States. President Biden’s decision to ease longstanding restrictions on foreign travelers this month promised to stimulate that rebound. It isn’t yet clear how or whether the Omicron variant will affect travel demand, but if travel bans proliferate and concerns over the variant continue to spread, hopes for an accelerated international rebound could be dashed once again.
Only two U.S. carriers, Delta Air Lines and United Airlines, fly out of southern Africa. Both have said that they are not yet planning to adjust their schedules in response to the administration’s ban, which takes effect on Monday and does not apply to American citizens or lawful permanent residents. Delta operates three weekly flights between Atlanta and Johannesburg. United operates five flights a week between Newark and Johannesburg, and it has not changed its plans to restart flights between Newark and Cape Town on Wednesday. None of the countries that have announced the new travel restrictions are major sources of business for U.S. carriers.
No major American airline has announced any substantive changes to procedures because of the variant. And all passengers flying into the United States must provide proof of a negative coronavirus test, with noncitizens also required to be fully vaccinated.
Within the United States, air travel has nearly recovered, even with many businesses still wary of sending employees on work trips. The number of people screened at airport security checkpoints over the past week was down only 10 percent from the same week in 2019, according to the Transportation Security Administration. And the industry successfully weathered the crush of travelers, avoiding the disruptions that at some airlines lasted for days in recent months.
In announcing on Monday that its borders would be closed to travelers from everywhere, Japan adopted a familiar tactic. The country has barred tourists since early in the coronavirus pandemic, even as most of the rest of the world started to travel again.
And it had only tentatively opened this month to business travelers and students, despite recording the highest vaccination rate among the world’s large wealthy democracies and after seeing its coronavirus caseloads plunge by 99 percent since August.
Now, as the doors slam shut again, Japan provides a sobering case study of the human and economic cost of those closed borders. Over the many months that Japan has been isolated, thousands of life plans have been suspended, leaving couples, students, academic researchers and workers in limbo.
Ayano Hirose has not been able to see her fiancé, Dery Nanda Prayoga, in person for the past 19 months, since he left Japan for his native Indonesia, just two weeks after her parents blessed their marriage plans. The couple has made do with multiple daily video calls. When they run out of things to talk about, they play billiards on Facebook Messenger or watch Japanese variety shows together online.
“We don’t want to suffer in pain at the thought of not being able to reunite in the near future,” said Ms. Hirose, 21, who has written letters to the foreign and justice ministries asking for an exemption to allow Mr. Dery to come to Japan. “So we will think positively and continue to hold out hope.”
At the first BTS concert of the coronavirus era on Saturday, Maggie Larin, 25, and her three friends were surrounded by a roaring crowd of 70,000 other fans in SoFi Stadium in Inglewood, Calif.
But when Lee Hye Su, 23, and her two friends go to see the K-pop group The Boyz in Seoul Olympic Park next weekend, she will be seated silently, masked and socially distanced, alongside only 2,100 other fans, according to the venue’s rules.
As K-pop bands start touring the world and performing for live audiences again, fans in their home country, South Korea, are flocking to stadiums. But they must abide by the government’s strict rules: no shouting, chanting or singing along at concerts with 500 or more attendees.
“We’ll only be able to clap when we enter the hall,” said Ms. Lee, who has followed the band since 2018. She said it was unfortunate that the atmosphere on Saturday would be different from that of past concerts, where she could yell all she wanted.
“But I knew I had to go as soon as I found out about it,” she said.
Live K-pop concerts are returning to South Korea as hospitalizations are rising across the country and the spread of a new variant alarms the world. The health minister, Kwon Deok-cheol, said on Friday that the government was considering tightening some restrictions because the number of available beds for critically ill patients in and around Seoul was “reaching a limit.”
But there is pent-up demand for live performances. K-pop fan groups have remained active throughout the pandemic, said Kim Hong Ki, chief executive of Space Oddity, a South Korean music collective. Record sales for K-pop groups have even spiked, he said.
“In K-pop, fans aren’t ordinary consumers, but active, evangelistic and dedicated to their fandom, almost religiously,” said Mr. Kim, who has worked in the South Korean music industry for decades. “When the rules are relaxed to some extent, fans will be chasing after live shows.”
Several other bands, like NCT 127 and Twice, have scheduled their first pandemic-era concerts in South Korea for next month. And thousands of K-pop fans in the country are dashing for tickets, even if they know those shows could get canceled.
Pandemic rules in the United States require fans to wear masks in concert halls, and provide proof of full vaccination, negative virus test results and photo identification upon entry. Still, the BTS concert in California this weekend was sold out months in advance.
To catch the show, Ms. Larin took a weekend away from law school in Michigan.
“I’ve been spending a lot of time preparing for the actual concert, listening to a lot of their music and learning their fan chants,” she said before the event on Saturday. “It’s going to be a very emotional experience.”