Here are 10 things to know about the new COVID-19 variant:
The B.1.1.529 variant has 50 mutations overall, including more than 30 on the spike protein alone. The spike protein is the target of most current COVID-19 vaccines and is what the virus uses to unlock access to our body's cells. Researchers are still trying to confirm whether this makes it more transmissible or lethal than earlier variants.
There are also 10 mutations on the receptor binding domain part of the variant, compared to two for the Delta variant. The Delta Plus that mutated from the latter was characterised by the K417N mutation on the spike protein; this has been linked to immune escape, but it is unclear if this is among the mutations in B.1.1.529.
There is speculation on the variant's origin, but it may have evolved from a single patient. Francois Balloux, the Director of the London-based UCL Genetics Institute, has said it "likely evolved during a chronic infection of an immuno-compromised person, possibly in an untreated HIV/AIDS patient".
First identified in South Africa this week, the strain has spread to nearby countries, including Botswana, where fully vaccinated people have been infected. In South Africa over 100 cases have been linked to this variant, with four more in Botswana.
Two cases have been detected in Hong Kong - where travellers (who got the Pfizer jab) from parts of southern Africa were isolated in separate rooms. Samples had "very high" viral loads, epidemiologist Dr Eric Feigl-Ding said. "PCR Ct values of 18 and 19... insanely high considering they were negative on recent PCR tests," he said.
Because the patients were in separate rooms, there is concern this variant is airborne. "... looks like vaccine evasion could be real with this variant... and yes, it is very airborne. Hotel guests were in different room across the hallway. Environmental samples found the virus in 25 of 87 swab across both rooms," Dr Feigl-Ding tweeted.
Israel has said it has identified a case of a COVID-19 variant with a large number of mutations "in a person who returned from Malawi", its health ministry was quoted by news agency AFP, adding that two more people had been placed in quarantine.
On Thursday India called for rigorous screening of passengers from South Africa, Botswana and Hong Kong. "This variant... has serious public health implications in view of recently relaxed visa restrictions and opening of international travel," the ministry said.
The UK, Singapore and Israel have stopped flights from South Africa, Botswana and four other African nations. Germany and Italy have also banned most travel from South Africa, news agency AFP said. South Africa has criticised the UK's decision as "rushed".
The World Health Organization has called for caution in the initial stages of dealing with this variant; more research needs to be conducted to understand how B.1.1.529 behaves, the global health body said. Dr Maria Van Kerkhove, WHO's COVID-19 Technical Lead, underlined the importance of ensuring complete vaccination.
With input from AFP, Bloomberg, Reuters