Scientists are racing to establish whether the vaccines currently being used across the globe are effective against the so-called 501Y.V2 variant, identified by South African genomics experts late last year in Nelson Mandela Bay.
"This lineage exhibits complete escape from three classes of therapeutically relevant monoclonal antibodies," the team of scientists from three South African universities working with the National Institute for Communicable Diseases (NICD) wrote in a paper published in the bioRxiv journal.
The 501Y.V2 variant is 50% more infectious than previous ones, South African researchers said this week. It has already spread to at least 20 countries since being reported to the World Health Organisation in late December.
It is one of several new variants discovered in recent months, including others first found in England and Brazil.
The variant is the main driver of South Africa's second wave of COVID-19 infections, which hit a new daily peak above 21,000 cases earlier this month, far above the first wave, before falling to about 12,000 a day.