A new coronavirus variant, B.1.1.529, has spread rapidly in South Africa.
A chart from the country's Health Department shows how it shot to dominance in one province.
The variant's high level of mutations to the spike protein is causing concern for scientists.
A chart from South African officials shows how a new coronavirus variant quickly came to dominate in a province of the country, supplanting the Delta variant.
It was shown in a briefing from South Africa's Department of Health on Thursday warning about the B.1.1.529 variant.
As of Friday, the variant had been detected in South Africa, Botswana, and Hong Kong. Its origin is unclear.
Prof. Tulio de Oliveira, director of the Centre for Epidemic Response & Innovation near Cape Town, said the data in the chart is from samples taken in Gauteng province from November 12 to November 22.
In that period, B.1.1.529 completely overtook the Delta and Beta variants that were present in Gauteng. The variant has rapidly increased there and is may already be present in most of the country's provinces, he said.
B.1.1.529 - represented by the blue part - represented 75% of cases detected within just two weeks. Its ascent was much faster than the Beta (green) and Delta (red) variants, which each took months to become dominant.
de Oliveira said that the B.1.1.529 cases were drawn from 77 samples - a relatively small number, but with a clear direction of travel.
The Financial Times produced another chart illustrating the speed of the variant's rise:
The increase in infections from the variant in Gauteng "shocked" de Oliveira and his colleagues, he told the South African channel SABC News.
One of the biggest fears about the variant is that its high levels of mutation in its spike protein could inhibit the body's immune response, as Insider's Dr Catherine Schuster-Bruce reported.
Speaking to SABC News, de Oliveira said it is too early to know if the vaccine will work against B.1.1.529, but said scientists expect it to hold "against hospitalizations and deaths."
"Vaccines are the strongest weapon in our arsenal to fight that virus," he said. He also called for people to avoid mass gatherings and to wear masks as scientists track the variant.
The UK has blocked flights from 6 African countries in response to the alarm, with the EU considering similar moves.