NSW recorded nine new locally acquired COVID-19 cases overnight, found amid a record 60,000-plus tests.
NSW Premier Gladys Berejiklian said seven of the cases were directly linked to Avalon, while a further two were under investigation.
One of those two was a man in his 20s who lives in the Northern Beaches, but has not yet been linked to the Avalon cluster.
Another was found in a man in his 40s who worked in the Sydney CBD, and Ms Berejiklian said there were fears this worker could have passed the virus on to people in other communities.
She also praised the "beyond amazing and encouraging" daily test results.
"I nearly fell off my chair when we realised that 60,000 people had come forward for testing," she said.
"Given the number of tests and given the number of cases, the results are positive."
The previous testing record was just over 42,000.
Ms Berejiklian said people should continue to get tested on Christmas and Boxing Day, with more than 300 clinics to be open during the holidays.
"Please do not move around if you don't have to," she said.
"We don't want people moving around unless you absolutely have to. It's really important to reduce your mobility."
She said masks were recommended indoors, and people should regularly use hand sanitiser.
NSW Chief Health Officer Dr Kerry Chant said the Avalon cluster now numbers 104.
"It is important that we're not complacent today," she said.
"If you have the mildest symptoms and you are anywhere in NSW, please get tested."
Nine new cases acquired overseas were found in the 24 hours to 8pm, bringing the total cases in NSW since the start of the pandemic to 4,634
More Sydney venues on alert
NSW Health said one of the cases reported today attended the Paragon Hotel Sports Bar near Circular Quay in Loftus Street between 12.45pm and 3.30pm on December 16.
A second person identified this morning, and who will appear in tomorrow's numbers, also attended the Paragon at the same time.
Patrons who were in the Sports Bar from 12.45pm to 3.30pm on December 16 for more than one hour and are considered a close contact and must get tested immediately and self-isolate for 14 days regardless of their result.
Anyone who was there for less than one hour needs to get tested immediately and self-isolate pending a negative result.
People who attended other areas of the Paragon Hotel during this time should monitor for symptoms and isolate and get tested immediately if symptoms appear. These people should have a very low threshold for testing.
Another of today's new cases under investigation is an office worker in the vicinity of Hunter and Bligh Streets in Sydney's CBD.
Anyone who has been in the north eastern part of the city, including the Australia Square, MLC Centre and Chifley Square, should be alert for symptoms and isolate immediately and get tested should even the mildest of symptoms develop.
Likewise who attended the pool deck area of Bondi Icebergs on December 20 between 8am and 9:30am or December 21 between 7am and 8am are asked to get tested immediately and self-isolate.
COVID-19 cases linked to the Avalon cluster have visited a growing list of locations across Sydney.
A full list of locations and public transport routes, and the associated public health advice, is available from the NSW Government website at https://www.nsw.gov.au/covid-19/latest-news-and-updates.