Delta has quickly become the dominant COVID variant in many countries across the world, in this episode we ask why. Over the past few weeks, a slew of studies have started to shed more light on how the Delta variant differs from its cousins and even the mechanisms behind its rampant spread. We dig into studies on the epidemiology and molecular biology of Delta to ask some key questions surrounding its transmissibility, lethality and what all this might mean for vaccine roll outs.