Twitters bad for rumours (and fights) - but we should expect someone like Peston to be telling the truth. The Independent has named his source but there's an additional paragraph :) "John Bell, regius professor of medicine at University of Oxford, who sits on the government?s vaccine taskforce, said on Sunday there was a ?big question mark? as to whether the vaccines currently being rolled out would work on the South African variant." "However, Professor Bell also said it was "unlikely? the mutation would make vaccines entirely ineffective, and it should be possible to tweak existing vaccines in around four to six weeks. ?Everybody should stay calm ? it?s going to be fine,?" https://www.independent.co.uk/news/uk/politics/covid-variant-south-africa-matt-hancock-b1781903.html