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. News: The mutation that helps Delta spread like wildfire News: COVID vaccines protect against Delta, but their effectiveness wanes  News: How do vaccinated people spread Delta? What the science says News: Delta coronavirus variant: scientists brace for impact News: Delta’s rise is fuelled by rampant spread from people who feel fine Subscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday.   See acast.com/privacy for privacy and opt-out information.