A lockdown of Australia's largest city Sydney has been extended to the end of September as authorities struggle to contain a wave of Delta cases of COVID 19.<br />'' <br />''The city's five million residents have been under stay-at-home orders since late June.Infections have more than doubled in the past week. There were 642 new cases on Friday, after 681 on Thursday.<br />'' <br />''From Monday, two million residents in the city's worst-hit suburbs will live under a daily curfew. Australia set a record on Thursday for its highest daily infections since the pandemic began.<br />'' <br />''Currently over half of Australia's 25 million people are living in lockdown, amid Delta outbreaks also in Melbourne and Canberra.<br />'' <br />''Sydney remains the biggest concern. So far, its outbreak has killed 65 people. Australia has recorded 971 deaths from Covid, fewer than many nations.<br />'' <br />''<span style="color: #222222;">Residents in Melbourne on Thursday marked their 200th day of lockdown since the pandemic began. Vaccinations have picked up in recent weeks. More than a quarter of Australians are fully vaccinated. </span><br />