Coronavirus: EU to block flights after Belgium new variant case
The variant, currently known as B.1.1.529, has also been identified in South Africa, Botswana, Hong Kong and Israel.
The World Health Organization (WHO) is meeting to discuss the development.
Scientists say they still have much to learn about the virus's new mutations.
The WHO has said it will take a few weeks to understand the impact of the new variant, as experts work to determine how transmissible it is.
The variant is yet to be given a more memorable name, like Delta or Beta. The WHO is expected to name it on Friday, and announce whether it is a variant of concern or just a variant of interest.
It is very different to the other variants that have emerged so far. Scientists have said it is the most heavily mutated version yet, which means Covid vaccines, which were designed using the original strain from Wuhan, may not be as effective.
What do we know about the new variant so far?
South Africans fear impact of new variant measures
Covid map: Where are cases the highest?
Stock markets across the world fall sharply on Friday, amid investor fears over the potential economic impact.
In London, the FTSE 100 share index dropped by nearly 3%, while markets in Germany and France also declined following falls in Asia.
Where have cases been detected so far?
The WHO says so far fewer than 100 sample sequences have been reported. Cases have mainly been confirmed in South Africa, but have also been detected in Hong Kong, Israel, Botswana and Belgium.
UK Health Secretary Sajid Javid said on Friday that the variant is "highly likely" to have spread to other countries.
Most of the cases in South Africa have been from its most populated province, Gauteng, of which Johannesburg is the capital city.
Only about 24% of South Africa's population is fully vaccinated, which could spur a rapid spread of cases there, Dr Mike Tildesley, a member of the Scientific Pandemic Influenza Modelling group (Spi-M), told the BBC on Friday.
In Hong Kong, the infections were found in a person who had arrived from South Africa, and a guest in the same quarantine hotel who tested positive a few days later, the Department of Health revealed. Both were fully vaccinated.
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Europe has identified its first case of the variant in Belgium. The Guardian reports that the case emerged in an unvaccinated young woman who had recently travelled from Egypt via Turkey and developed mild flu symptoms 11 days later.
Israel's Prime Minister Naftali Bennett said on Friday it is "on the verge of a state of emergency" regarding the new variant, and that he would "act fast, strong and now".
One case was detected in a person who returned from Malawi, according to Israeli media reports quoting the country's health ministry. Another two suspected infections were yet to be confirmed with test results. All three are said to have been fully vaccinated.
What are different countries doing to stop the spread?
The WHO has warned against countries hastily imposing travel restrictions, saying they should look to a "risk-based and scientific approach."
Nevertheless, an increasing number of nations including the UK and the Netherlands have temporarily halted flights from these southern African countries:
South Africa
Botswana
Namibia
Zimbabwe
Eswatini (formerly Swaziland)
Lesotho
The Head of the European Commission, Ursula von der Leyen, has called for all EU nations to put on the "emergency brake" and stop flights from the region.
"It is now important that all of us in Europe act very swiftly, decisively and united," she said on Friday.
The EU is already struggling to cope with fresh waves of the virus, and several countries have re-imposed lockdowns and restrictions.
Singapore, Italy, France and Israel are among those who have also placed Mozambique on their red lists.
The Czech Republic will ban anyone who has spent more than 12 hours in those nations and also Zambia from entering as of Saturday.
Japan has announced that from Saturday, travellers from much of southern Africa will need to quarantine for 10 days and take a total of four tests during that time.
"The key to crisis management is to prepare for the worst," the Japan Times newspaper quoted chief cabinet secretary Hirokazu Matsuno as saying.
Japan has announced that from Saturday, travellers from much of southern Africa will need to quarantine for 10 days and take a total of four tests during that time.
"The key to crisis management is to prepare for the worst," the Japan Times newspaper quoted chief cabinet secretary Hirokazu Matsuno as saying.
Japan has announced that from Saturday, travellers from much of southern Africa will need to quarantine for 10 days and take a total of four tests during that time.
"The key to crisis management is to prepare for the worst," the Japan Times newspaper quoted chief cabinet secretary Hirokazu Matsuno as saying.
Japan has announced that from Saturday, travellers from much of southern Africa will need to quarantine for 10 days and take a total of four tests during that time.
"The key to crisis management is to prepare for the worst," the Japan Times newspaper quoted chief cabinet secretary Hirokazu Matsuno as saying.
Japan has announced that from Saturday, travellers from much of southern Africa will need to quarantine for 10 days and take a total of four tests during that time.
"The key to crisis management is to prepare for the worst," the Japan Times newspaper quoted chief cabinet secretary Hirokazu Matsuno as saying.