mutations in the 501Y.V2 "are really pretty substantial chanSouth African super strain, 501Y.V2, has more mutations than the UK strain. "I would worry a lot about the South African strain," John Bell, the Oxford University scientist who worked on the Oxford AstraZeneca vaccine, toldThe Times. He said mutations in the 501Y.V2 "are really pretty substantial changes in the structure of the [virus's spike] protein."