SYDNEY, Aug 23 (Reuters) - Australia must start to learn to live with COVID-19 when higher vaccination targets are reached, Prime Minister Scott Morrison said on Monday, despite concerns in some states about the impact of a surge in cases in Sydney. With over half of all Australians stuck in weeks-long lockdowns to curb the highly infectious Delta strain, Morrison said the country had to move forward and start reducing restrictions as more people became vaccinated. "(Lockdowns) cannot go on forever. This is not a sustainable way to live in this country," he said during a televised media conference in Canberra. "This groundhog day has to end, and it will end when we start getting to 70% and 80% (vaccination rates)." Morrison spoke just as tighter restrictions took effect in Australia"s largest city, Sydney. As of Monday, masks are mandated outside the home, except when exercising, and a night time curfew is in place in the 12 worst-affected council areas. The federal government last month unveiled a four-stage plan to relax restrictions once 70% of its 25 million people aged over 16 are vaccinated, with stringent lockdowns "unlikely" to be required. When vaccination coverage reaches 80% only "highly targeted lockdowns" would be necessary and inoculated Australians would be free to travel interstate. Differences have emerged between states that want to maintain a focus on suppressing the virus and the largest state of New South Wales, which is seeking a path out of lockdowns through vaccinations following a large Delta outbreak. Western Australia and Queensland states, which are largely coronavirus-free, have flagged they may still maintain some restrictions even when vaccination targets are reached. A masked man rides a scooter through the quiet city centre during a lockdown to curb the spread of a coronavirus disease (COVID-19) outbreak in Sydney, Australia, August 23, 2021. REUTERS/Loren Elliott A staff member stands at the entrance of a COVID-19 clinic during a lockdown to curb a coronavirus disease outbreak in Sydney, Australia, August 20, 2021. REUTERS/Loren Elliott Australian Prime Minister Scott Morrison looks on during a news conference with French President Emmanuel Macron in front of the Elysee Palace in Paris, France, June 15, 2021. REUTERS/Pascal Rossignol 1/5 A staff member stands at the entrance of a COVID-19 clinic during a lockdown to curb a coronavirus disease outbreak in Sydney, Australia, August 20, 2021. REUTERS/Loren Elliott They say the national plan, which was agreed before the NSW outbreak, was based on having only small outbreaks present in the community. On Monday, NSW reported 818 cases, most of them in Sydney, slightly down from the record 830 a day earlier. NSW Premier Gladys Berejiklian urged people to focus less on cases and more on the immunisation rollout. "Once you get to 80% double dose, every state will have to live with COVID. You cannot keep Delta out forever," she said. In Victoria, home to Melbourne, 71 new cases were detected with 55 having spent time in the community while infectious, which state Premier Daniel Andrews said could derail plans to exit lockdown on Sept. 2. While Australia has managed the pandemic better than many other developed countries, a slow vaccine rollout has taken the gloss off its early success. Nationally, 30% of people above 16 are fully vaccinated, while 52% have had a least one dose. Vaccinations are running at a record pace but the target of 80% fully vaccinated will not be reached until December at the current rate. Australia has reported just over 44,600 cases in total. There have been 984 deaths, although the death rate has declined since last year. Separately on Monday, South Australia said it would be the first state to trial home quarantine for people returning from other states, with an app used to track whether people are staying home. If successful the trial would be used for some returning international travelers to ease pressure on hotel quarantine.