LONDON: The Delta coronavirus variant of concern, first identified in India, is believed to be 60% more transmissible than the Alpha variant which was previously dominant in Britain, a prominent UK epidemiologist said on Wednesday. "Last week, we had evidence that the Delta variant had something between 30 to 100% transmission advantage over the Alpha variant... And that's firmed up we think 60% is probably the best estimate," Neil Ferguson of Imperial College London told reporters.