The nine new cases were diagnosed in the 24 hours to 8pm on Monday night from 12,494 tests.

NSW Health said five of the new cases were linked to a known local case or cluster, one did not have a known source, and three were returned overseas travellers in hotel quarantine.

Three of the locally acquired cases are linked to the outbreak at Concord Hospital, including two healthcare workers, and a visitor to the emergency department.

The boarder at Kincoppal Rose Bay School of the Sacred Heart at Rose Bay in Sydney's east is linked to the CBD cluster.

All boarders and staff in the boarding area have been identified as close contacts and boarding operations at the school have been suspended, while students isolate at home with their families.

One new case is a household contact of a previously reported case linked to the CBD cluster. There are now 66 cases linked to that cluster.

The two healthcare workers reported on Tuesday worked at Concord Emergency Department and contact tracing is underway. They had no symptoms while at work and wore personal protective equipment while caring for patients.

Seven people associated with Concord and Liverpool hospitals have tested positive for COVID-19, including six healthcare workers. The investigation into the source of these infections is ongoing.

Chief Health Officer Kerry Chant said on Monday there was no evidence to suggest NSW hospitals weren't operating safely and effectively, and urged people not to delay urgent care.

NSW Health says anyone who attended the following venues at these times is considered a casual contact and must monitor for symptoms and get tested immediately if they develop. After testing, they must remain in isolation until a negative test result is received:

* Charles St Kitchen, at Putney on Saturday between 10.45am and 11.30am

* Eastwood Ryde Netball Association, Meadowbank Park, on Saturday between 12.15pm and 1.30pm

* Missing Spoon Cafe on Saturday between 4.45pm and 5.30pm

* Croydon Park Pharmacy on Thursday between 1pm and 2pm

Anyone who attended the following venue at these times are considered close contacts and are being directed to get tested and isolate for 14 days, and stay isolated for the entire period, even if the test is negative:

* Plus Fitness, Epping on Saturday between 9am and 10.15am

NSW Health is treating 79 COVID-19 cases, including seven in intensive care, three of whom are being ventilated. Eighty-four per cent being treated by NSW Health are in non-acute, out-of-hospital care.

Australian Associated Press