NSW Health says there were no cases of the virus recorded in the 24 hours to 8pm on Wednesday night from 14,885 tests.

NSW last reported no locally or overseas acquired cases on September 27.

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NSW Health is treating 81 COVID-19 cases, none of whom are in intensive care. Most cases, 96 per cent, are being treated by NSW Health in non-acute, out-of-hospital care.

"Although NSW has enjoyed 19 days without a locally acquired case of COVID-19 and restrictions continue to be eased, now is not the time to be complacent," a NSW Health statement said on Thursday.

"Everyone is encouraged to continue to come forward for testing if they have any symptoms that could signal COVID-19, as this is the best way to detect and stop the spread of the virus," it said.

It warned that new infections had been identified in the past after a number of days without any cases because of transmission among people who had mild or no symptoms.

South Australia has added Woodville High School in Adelaide's western suburbs to its list of venues of concern. Anyone in NSW who attended the school on Monday must get tested, isolate immediately, and contact NSW Health on 1800 943 553.

Anyone who has been in South Australia in the past two weeks should monitor the SA Health website for updated advice:

Residents in a number of suburbs in southwestern Sydney were also urged to get tested after virus fragments were detected in the sewage earlier this week.

Meanwhile, from Tuesday a swathe of restrictions will be eased in NSW with 30 visitors allowed in homes - 50 if there's an outdoor space - while the capacity at small hospitality venues will double and people from Sydney will be allowed back in Queensland.

- Australian Associated Press

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