NSW Health Minister Brad Hazzard said he was notified of the new case early on December 3.
“She worked at the Novotel and the Ibis at Darling Harbour. One of those is a police quarantine hotel,” he told Seven’s Sunrise program.
“The good news is her five family members were tested overnight and they are all negative, so that is a good outcome.”
NSW Health is asking anybody who worked at the Ibis last Friday or at the Novotel on Saturday, Sunday or Monday to monitor for symptoms, self-isolate and get tested.
As a precaution, NSW Health is also conducting wider testing of staff at the hotel complex.
“The source of this new infection is under investigation,” a NSW Health spokesperson said in a statement on Thursday.
“Urgent genome sequencing is underway to determine whether this is an infection acquired in the community or through work at the hotel quarantine facility. ”
“These results are expected in the next 24 to 48 hours.”
The woman, who lives in southwestern Sydney, travelled from Minto to Central and on the Light Rail from Central to Darling Harbour on a number of occasions while potentially infectious.
NSW Health is confirming the woman’s route, and is asking people who travelled on the same services to get tested immediately and self-isolate until further notice.
The news comes a day after NSW recorded 25 consecutive days without a single case in the community and Premier Gladys Berejiklian announced a swathe of social restrictions would be eased from Monday.
Chief Health Officer Kerry Chant said on Wednesday she believed the state had probably virtually eliminated community transmission.
Berejiklian said she anticipated there would be more cases.
Hazzard said he also anticipated there would be more cases “because we are in a pandemic”.
“What we have done is open up NSW in a way that is probably world-leading at the present time… We have led the way in Australia,” he said.
He also urged anyone with any symptoms to get tested as soon as possible.
“Please don’t go to work, please don’t go shopping and stay home,” he said.
Meanwhile, NSW Health is calling on people in Sydney’s northwest to get tested if they have even mild symptoms after traces of the virus were detected at a sewage treatment plant in Riverstone.
Fragments of the virus were detected in samples taken on Sunday from the sewerage system that drains parts of Riverstone, Vineyard, Marsden Park, Shanes Park, Quakers Hill, Oakville, Box Hill, The Ponds, Rouse Hill, Nelson, Schofields and Colebee.