The Omicron variant of the coronavirus has appeared in an increasing number of European countries, leaving governments around the world scrambling to stop the spread.
The UK on Saturday tightened its rules on mask-wearing and on testing of international arrivals after finding two cases.
New cases were also confirmed in Germany and Italy, with Belgium, Israel and Hong Kong also reporting that the variant has been found in travellers.
In the US, Dr Anthony Fauci, the government’s top infectious diseases expert, said he would not be surprised if the Omicron variant was already in the country.
“We have not detected it yet, but when you have a virus that is showing this degree of transmissibility … it almost invariably is ultimately going to go essentially all over,” Dr Fauci said on NBC television.
Because of fears that the new variant has the potential to be more resistant to the protection offered by vaccines, there are growing concerns around the world that the pandemic and associated lockdown restrictions will persist for far longer than hoped.
Nearly two years since the start of the pandemic that has claimed more than 5 million lives around the world, countries are on high alert.
Many have already imposed travel restrictions on flights from southern Africa as they seek to buy time to assess whether the Omicron variant is more transmissible than the current dominant delta variant.
In England, Prime Minister Boris Johnson said it was necessary to take “targeted and precautionary measures”, such as increased mask-wearing, after two people tested positive for the new variant.
He told a news conference: “Right now this is the responsible course of action to slow down the seeding and the spread of this new variant and to maximize our defences.”
The British government also added four more countries — Angola, Malawi, Mozambique and Zambia — onto the country’s travel red list from Sunday.
Six others — Botswana, Eswatini (formerly Swaziland), Lesotho, Namibia, South Africa and Zimbabwe — were added on Friday.
Many countries have slapped restrictions on various southern African countries over the past couple of days, including Australia, Brazil, Canada, the EU, Iran, Japan, New Zealand, Thailand and the US, in response to warnings over the transmissibility of the new variant.
This goes against the advice of the World Health Organisation (WHO), which has warned against any overreaction before the variant was thoroughly studied.
Despite the banning of flights, there are mounting concerns that the variant has already been widely seeded around the world.
Italy and Germany were the latest to report confirmed cases of the Omicron variant.
An Italian who had travelled to Mozambique on business landed in Rome on November 11 and returned to his home near Naples.
He and five family members, including two school-age children, have since tested positive, the Italian news agency LaPresse said. All are isolating in the Naples suburb of Caserta in good condition with light symptoms.
Italy’s health ministry is urging all regions to increase its tracing of the virus and sequencing to detect cases of the new variant first identified in South Africa.
In Germany, the Max von Pettenkofer Institute, a Munich-based microbiology centre, said the Omicron variant was confirmed in two travellers who arrived on a flight from South Africa on November 24.
The Dutch public health institute said the Omicron variant was “probably found in a number of the tested persons” who were isolated after arriving on Friday in Amsterdam on two flights from South Africa.
The institute said in a statement that further sequencing analysis is underway to determine for sure that it is the new variant. The results were expected on Sunday. A total of 61 people were tested.
Israel said it detected the new strain in a traveller who had returned from Malawi and was tracing 800 travellers who returned recently from southern African countries.
And Australia said on Sunday its scientists were working to determine whether two people who tested positive for Covid after arriving from southern Africa are infected with the Omicron variant.
The variant’s swift spread among young people in South Africa has alarmed health professionals even though there was no immediate indication whether the variant causes more severe disease.