NSW has recorded five new local COVID-19 cases, including a man in his 40s who sought medical treatment at a western Sydney hospital emergency department and was diagnosed with the virus.
Three locally-acquired cases were recorded in the 24 hours to 8pm on Sunday, all connected to the 26-person Berala cluster.
Another two were confirmed after the 8pm cut-off - a man in his 40s who presented at Mount Druitt Hospital on Saturday with respiratory illness, along with one of his household contacts.
The man was confirmed COVID-positive and transferred to Westmead Hospital for treatment, while Mount Druitt Hospital emergency department has been deep cleaned and will re-open on Monday.
"Investigations are under way to assess potential close contacts, including staff and patients," Western Sydney Local Health District said in a statement.
"Anyone determined to be at risk of possible exposure is being contacted by the Public Health Unit and health advice provided."
Another eight COVID-19 cases were uncovered in travellers in hotel quarantine.
Chief health officer Dr Kerry Chant on Monday told reporters the risk profile for other people in the emergency department at that time is still undetermined.
The potential Mount Druitt exposure incident comes as NSW continues to "mop up" two Greater Sydney outbreaks.
The 24-hour tally of three positive people came from more than 18,000 tests, prompting fresh calls from authorities for an uptick in testing.
"NSW under the circumstances is doing relatively well but we are in the phase of mopping up, we are in the phase of really trying to identify any community transmission," Premier Gladys Berejiklian said.
"(We want) to make sure any chains which exist in the community which we hadn't picked up before have been and are being picked up.
"The case regarding the patient at Mount Druitt emergency department is still under investigation, so there's no direct link yet."
A number of new venues, including the Costco in Casula and Myer in Bankstown, have also been declared potential exposure sites.
Late on Sunday, NSW Health also issued an alert for Bankstown Central Shopping Centre over two separate days, as well as a Service NSW site in Bankstown and a Thai supermarket at Marrickville.
Anyone who visited the venues at specific times must get tested immediately and self-isolate until receiving a negative result.
Meanwhile, residents from the northern part of Sydney's Northern Beaches celebrated "Freedom Day" on Sunday, having been let out of lockdown.
But Ms Berejiklian warned NSW residents hotel quarantine leaks and local virus outbreaks would likely continue to occur around the state, regardless of the stringency of quarantine regulations.
She also said regulations had changed from Monday to enforce mask usage at all times for hotel quarantine workers.
"We have to be very honest - there is no way of eliminating this virus so long as it exists around the world," Ms Berejiklian said.
"Perfection is not possible during a pandemic. As much as we'd like to think there is perfection, there's not. We have to assume there will be incidents where there's concern but let's put things into perspective.
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