The science behind the Covid Delta variant that’s shutting down Australia

A strain of Covid-19, called the Delta variant, has spread across Australia, triggering lockdowns in multiple states and territories. Governments and health experts worldwide have warned that this variant is highly infectious, with the NSW premier describing transmission in a recent case as “scarily” fleeting. Medical editor Melissa Davey explains what we know about the Delta variant, and the challenges this strain could pose in containing Australia’s outbreak