Governments have taken steps to tighten their borders as cases of the Omicron variant of coronavirus appeared in countries on opposite sides of the world.
Poland is the latest to take action, suspending flights to seven southern African countries where the new variant was first detected.
Health Minister Adam Niedzielski said that travellers from those countries would have to quarantine for 14 days.
The new rules are to begin on Wednesday and last until December 17.
Japan had earlier taken action as it said it would suspend the entry of all foreign visitors from around the world.
“We are taking the step as an emergency precaution to prevent a worst-case scenario in Japan,” said Prime Minister Fumio Kishida. He said the measure will take effect on Tuesday.
The decision means Japan will restore border controls that it eased earlier this month for short-term business visitors, foreign students and workers.
Mr Kishida urged people to continue with mask wearing and other basic anti-virus measures until further details of the new Omicron variant are known.
Many countries have moved to tighten their borders even as scientists warned that it is not clear if the new variant is more alarming than other versions of the virus.
The variant was identified days ago by researchers in South Africa, and much is still not known about it, including whether it is more contagious, more likely to cause serious illness or more able to evade the protection of vaccines.
But South African doctors said on Monday that the rapid increase in cases attributed to the new Omicron variant is resulting in mostly mild symptoms.
Dr Unben Pillay, a GP in Gauteng province, where 81% of the new cases have been reported, said he had seen a sharp rise in new Covid-19 cases in the past 10 days.
But he said that so far the cases had been very mild, with patients having flu-like symptoms, dry coughs, fever, night sweats, some pain in the body. He said most had been treated at home.
He also said that vaccinated people were faring much better than the unvaccinated.
But many countries rushed to act, reflecting anxiety about anything that could prolong the pandemic that has killed more than five million people.
Australian authorities announced that they would delay plans to relax border restrictions by at least two weeks, until December 15, as the country reported its fifth case of the Omicron variant.
New South Wales state authorities reported on Sunday that two travellers from South Africa to Sydney had become Australia’s first cases of the new variant. Both were fully vaccinated, showed no symptoms and were in quarantine in Sydney.
On Monday, another two cases were confirmed in Sydney after arriving in Australia’s most populous state on a flight from southern Africa on Sunday, the state government said.
A South African man in his 30s who flew from Johannesburg to the northern Australian city of Darwin last Thursday also tested positive for the Omicron variant, officials said.
“The temporary pause will ensure Australia can gather the information we need to better understand the Omicron variant, including the efficacy of the vaccine, the range of illness, including if it may generate more mild symptoms, and the level of transmission,” a government statement said.
New South Wales and Victoria, as well as the national capital, Canberra, have introduced a blanket 72-hour quarantine requirement for all international arrivals.
Israel decided to bar entry to foreigners, and Morocco said it would suspend all incoming flights for two weeks starting on Monday — among the most drastic of a growing raft of travel curbs being imposed by nations around the world as they scrambled to slow the variant’s spread.
Scientists in several places — from Hong Kong to Europe to North America — have confirmed its presence. The Netherlands reported 13 Omicron cases on Sunday, and Canada has found two.
Noting that the variant has already been detected in many countries and that closing borders often has limited effect, the World Health Organisation (WHO) called for frontiers to remain open.
Dr Francis Collins, director of the National Institutes of Health in the United States, meanwhile, emphasised that there is no data yet that suggests the new variant causes more serious illness than previous Covid-19 variants.
“I do think it’s more contagious when you look at how rapidly it spread through multiple districts in South Africa. It has the earmarks therefore of being particularly likely to spread from one person to another. What we don’t know is whether it can compete with Delta,” said Dr Collins.
Dr Collins echoed several experts in saying the news should make everyone redouble their efforts to use the tools the world already has, including vaccinations, booster shots and measures such as mask-wearing.
“I know, America, you’re really tired about hearing those things, but the virus is not tired of us,” Dr Collins said.
The Dutch public health authority confirmed that 13 people who arrived from South Africa on Friday have so far tested positive for Omicron.
They were among 61 people who tested positive for the virus after arriving on the last two flights to Amsterdam’s Schiphol Airport before a flight ban was implemented. They were immediately put into isolation, most at a nearby hotel.
On Sunday, Dutch military police arrested a husband and wife who had left the hotel where they were being quarantined and had boarded a plane at Schiphol Airport.
Local media reported that the couple were trying to fly home to Spain.
A spokeswoman for the local security authority said on Monday that an investigation was under way into whether the couple had committed a crime and should be prosecuted.
“Quarantine is not obligatory, but we assume people will act responsibly,” said a spokeswoman, Petra Faber.
“These people are now in enforced isolation, no longer in our municipality but in a hospital elsewhere in the Netherlands,” Ms Faber said.
Canada’s health minister said the country’s first two cases of Omicron were found in Ontario after two individuals who had recently travelled from Nigeria tested positive.
Two German states reported a total of three cases in returning travellers over the weekend.
The US plans to ban travel from South Africa and seven other southern African countries starting from Monday.
“It’s going to give us a period of time to enhance our preparedness,” said the United States’ top infectious diseases expert, Dr Anthony Fauci.
Many countries are introducing such bans, though they go against the advice of the WHO, which has warned against any over-reaction before the variant is thoroughly studied.
Dr Fauci said it will take approximately two more weeks to have more definitive information on the transmissibility, severity and other characteristics of Omicron, according to a statement from the White House.
South Africa’s government responded angrily to the travel bans, which it said are “akin to punishing South Africa for its advanced genomic sequencing and the ability to detect new variants quicker”.
The WHO sent out a statement saying it “stands with African nations” and noting that travel restrictions may play “a role in slightly reducing the spread of Covid-19 but place a heavy burden on lives and livelihoods”.
It said if restrictions are put in place, they should be scientifically based and not intrusive.
In Europe, much of which already has been struggling recently with a sharp increase in cases, officials were on guard.
On Monday, the Scottish government announced the discovery of six new cases of the Omicron variant, taking the UK total to nine. It has asked public health authorities to undertake enhanced contact tracing in all cases.
“Questions remain about its severity, transmissibility and response to treatments or vaccines and scientists are working at pace to provide additional information,” said Scottish health secretary Humza Yousaf.
Over the weekend, health authorities in the UK found three cases of the variant, which prompted the British government to tighten rules on mask-wearing and testing of arrivals in the country.
Spain, which had announced it would not admit unvaccinated British visitors starting from December 1, has imposed a 10-day mandatory quarantine for visitors coming from seven southern African countries.
The mandatory isolation affects travellers from South Africa, Botswana, Eswatini, Lesotho, Mozambique, Namibia and Zimbabwe who arrive in Spain directly or after stopovers in other countries.
Foreign Minister Jose Manuel Albares said that more than 200 nationals who were in the region and whose flights had been cancelled would be brought back to Spain on flights that are still operating to parts of Europe.
One of Madrid’s major public hospitals said on Monday it had detected the first confirmed case of the Omicron variant in Spain, in a traveller from South Africa.
In a tweet, the microbiology and infectious disease service of the Gregorio Maranon Hospital said that the patient was in good condition.
In a statement, health authorities identified the patient as a 51-year-old man who had returned from South Africa on November 28 after a stopover in Amsterdam.
He had first tested positive for coronavirus in a screening with antigen tests at the airport in Madrid, the statement said, adding that authorities were watching other passengers who had been in close contact with him on the plane from the Netherlands.
Italy was going through lists of airline passengers who had arrived in the past two weeks. France is continuing to push vaccinations and booster shots.
David Hui, a respiratory medicine expert and government adviser on the pandemic in Hong Kong, agreed with that strategy.
He said the two people who tested positive for the Omicron variant had received the Pfizer vaccine and exhibited very mild symptoms, such as a sore throat.
“Vaccines should work but there would be some reduction in effectiveness,” he said.
Despite the global worry, some countries are continuing with previous plans to loosen restrictions, with signs of reopening in Malaysia, Singapore and New Zealand.
Malaysians working in Singapore held joyful reunions with loved ones after returning to their homeland following the partial reopening of a land border that was closed for nearly two years because of the pandemic.
Buses ferried fully vaccinated passengers across the Causeway Bridge that connects the island of Singapore with the Malaysian peninsula. Strict measures included pre-departure and on-arrival Covid-19 tests.
New Zealand announced it will continue plans to reopen internally after months of shutdown, while also restricting travel from African nations.
New Zealand Prime Minister Jacinda Ardern said bars, restaurants and gyms in Auckland can reopen from late Thursday, ending a coronavirus lockdown that began in August.
“We’ve come through the past two years of Covid in better shape than nearly anywhere in the world,” Ms Ardern said, pointing to low death rates, a growing economy and high vaccination rates.