Analysis: BBC and AP analysis of the new variant.

We're back in familiar territory - growing concern about a new variant of coronavirus.

The latest is the most heavily mutated version discovered so far - and it has such a long list of mutations that it was described by one scientist as "horrific", while another told me it was the worst variant they'd seen.

It is early days and the confirmed cases are still mostly concentrated in one province in South Africa, but there are hints it may have spread further.

Immediately there are questions around how quickly the new variant spreads, its ability to bypass some of the protection given by vaccines and what should be done about it.

There is a lot of speculation, but there are very few clear answers.

The variant is called B.1.1.529 and is likely to be given a Greek code-name (like the Alpha and Delta variants) by the World Health Organization on Friday.

It is also incredibly heavily mutated. Prof Tulio de Oliveira, the director of the Centre for Epidemic Response and Innovation in South Africa, said there was an "unusual constellation of mutations" and that it was "very different" to other variants that have circulated.