Business NSW’s Damien Kelly says an extension of Greater Sydney’s lockdown will be a “crippling blow” to businesses. The Sydney Opera House is on high alert after a subcontractor worked at the iconic building for six days while potentially infectious with Covid-19. A spokeswoman for the Sydney Opera House said it was informed by the health department that the subcontractor who worked between July 1 and 6 had returned a positive swab. “NSW Health is currently undertaking its investigations, and the Opera House is taking all necessary steps in line with its Covid Safety Plan,” the spokeswoman said. NSW Health has been contacted for comment and will provide an update on Covid-19 cases at 11am.