Scientists have new biological evidence that the so-called South African coronavirus variant binds more readily and strongly to human cells, making it more infectious, top local epidemiologist Salim Abdool Karim said on Monday.

He was speaking at a presentation of research into the variant, known as 501Y.V2, by a team of scientists. The variant was identified by South African genomics experts late last year.

It drove local COVID-19 infections to a new daily peak above 21,000 cases earlier this month.

British scientists and politicians have expressed concern that vaccines currently being deployed or in development could be less effective against the South African variant. It has more than 20 mutations including several in the spike protein the virus uses to infect human cells.

But Abdool Karim said there was as yet no answer to that question, although scientists around the world were working on it.

South African experts have said that since vaccines induce a broad immune response it is unlikely that the mutations in the spike protein would completely negate the effect.