In Sydney, the reminders keep coming that this outbreak is not like past outbreaks. The NSW Premier Gladys Berejiklian made the unsurprising announcement yesterday that the current lockdown would be extended for at least four more weeks, as daily case numbers of the Delta variant keep on rising. So has this outbreak gone so far that it's not possible to reach zero again? And if that's true, then what does opening up look like? Featured: Tony Blakely, Professor of Epidemiology, University of Melbourne