Scientists have detected a new Covid-19 variant called B.1.1.529 and are working to understand its potential implications.
About 50 confirmed cases have been identified in South Africa, Hong Kong and Botswana.
The variant has a very unusual constellation of mutations, which are worrying because they could help it evade the body’s immune response and make it more transmissible.
Any new variant that is able to evade vaccines or spread faster than the now-dominant Delta variant might pose a significant threat as the world emerges from the pandemic.
Dr Susan Hopkins, the chief medical adviser to the UK Health Security Agency, said the R value, or effective reproduction number, of the variant in a South African province, where it was first found, was now 2.,
That’s a level of transmission not recorded since the beginning of the pandemic before restrictions began to be imposed.
For an R of anything above 1, an epidemic will grow exponentially.
Senior scientists on Thursday evening described the new variant as the worst they had seen since the start of the pandemic.
It has 32 mutations in the spike protein, the part of the virus that most vaccines use to prime the immune system against Covid.
That is about double the number associated with the Delta variant.
Mutations in the spike protein can affect the virus’s ability to infect cells and spread, but also make it harder for immune cells to attack the pathogen.