There have been nine new cases of coronavirus in New South Wales, as a cluster linked to the emergency departments of two Sydney hospitals continues to grow.
Of those, only one was from hotel quarantine, seven are linked to a known cluster, and one case in southeastern Sydney has not been linked to any known source.
Chief health officer Dr Kerry Chant said two of the new cases are linked to the Sydney CBD cluster, with one attending the City Tattersalls Gym and another a household contact of a known case.
Five are linked to Concord and Liverpool Hospitals; two healthcare workers, one patient and two household contacts of that patient.
Investigations into the source of the outbreak are ongoing.
Premier Gladys Berejiklian said new cases over the past few days which health authorities believe are linked to surfaces, rather than transmission through the air, were a reminder that masks were not a complete defence against the virus.
"Please be careful about surfaces, please be careful about what you're touching," she said.
"If you have a symptom you have to stay home, and isolate."
Concord Hospital closed its doors to all visitors on Wednesday and will not reopen until 10am on Friday after multiple staff members tested positive to coronavirus.
Non-essential surgery will also be postponed during this time.
Sydney Local Health District said in a statement all staff who had so far tested positive were in isolation, while those identified as contacts are being tested and also isolating at home for 14 days.
More than 100 staff are believed to be in isolation, and the hospital will undergo a deep clean while its doors are closed.
There are now 12 cases associated with the Concord and Liverpool hospitals, and health authorities believe the virus may have been spread through a surface, as staff were wearing masks.
A spokeswoman for Liverpool Hospital told NCA NewsWire there had been no change to visiting hours for their hospital.