The majority of the state's 11 new reported COVID-19 cases are linked to known cases according to NSW Health's daily update.
NSW deputy chief health officer Jeremy McAnulty said of the 11 cases reported to 8pm on Thursday night, nine were locally acquired and linked to known cases.
This included one person with a confirmed case who attended the Apollo Restaurant in Potts Points, and eight who are close contacts of known cases.
Meantime one new case - a female in her 60s from south western Sydney - remains under investigation, and one new case was acquired in Victoria and has been in self isolation.
Another school in Newcastle has also been closed for cleaning, and contract tracing is underway. NSW Health has contacted St Francis Xavier's College, Hamilton East, after a household contact of a previously reported case attended the school from Monday to Wednesday this week.
"While most cases in the past week have been associated with local clusters and close contacts of known cases, some have not been linked to known cases," Dr McAnulty said, while urging people to continue to practise social distancing, hand hygiene and other precautions to stop the spread of COVID-19.
Victoria has recorded 450 new cases of COVID-19 in the past 24 hours, and 11 deaths.
The new cases in NSW bring the total number of cases to 3653, after one previous case was excluded after further testing. There were 27,937 tests undertaken across the state in the 24 hours, compared with 28,035 in the same period the previous day.
"Isolation is mandatory for anyone identified as a close contact of a case," Dr McAnulty said.
"Anyone directed to undertake a 14-day self-isolation period must stay in isolation for the full time, even if they test negative.
"Early testing may not detect an infection, and release from isolation based on a negative test could allow an infectious person to infect others in the community."
There are 109 COVID-19 cases being treated by NSW Health, with 10 patients in intensive care including five on ventilators.
The number of confirmed cases recorded so far in the Illawarra Shoalhaven Local Health District remains stable at 131.
The majority of people have recovered with just two active cases in the region, while one previously confirmed case has this week been excluded after further testing.
Almost 75,000 people have been tested in the region.
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