New South Wales has recorded one new community case of COVID-19 - the wife of the man who tested positive on Wednesday.
State Premier Gladys Berejiklian confirmed the new case during a 1pm (NZ time) press conference on Thursday.
She said it was "reassuring" no other close contacts have yet to return positive tests. An immediate family member, who does not live in the same household as both of the new cases, has tested negative.
Berejiklian also announced a raft of new measures, including compulsory face mask wearing in some places, limiting household gatherings to just 20 people and ruling all bar patrons must be seated. These restrictions will be in place until at least Monday - meaning they will be enforced during Mother's Day on Sunday.
"I appreciate that it's Mother's Day but we also appreciate that 20 people within the home is manageable for people to celebrate that important day," she said. "The restrictions will come into force at 5pm today."
The measures are being implemented after it was revealed the man who tested positive had visited a variety of locations including a movie theatre, a service station, an optometrist, a golf club and a meat store in Sydney's eastern suburbs while unknowingly infectious.
He was NSW's first community COVID-19 case in more than a month and health officials have been working to figure out how he acquired the virus without a clear border link.
"Urgent investigations into the source of their infections and contact tracing are ongoing," NSW Health said in a statement.
During the press conference, chief health officer Dr Kerry Chant said figuring out how the case was acquired has been "quite hard".
"This person had not come in contact with a quarantine or border worker, so the genomics was pivotal," she said, ABC reported.
A match has been found between the man and a traveller who tested positive while in managed isolation. Dr Chant said they were reviewing CCTV footage to look into how transmission occurred from the traveller.
"We can't find any direct link between our case, so what we're concerned about is there is another person that is as yet unidentified that infected our case, and then the hypothesis is that our case passed it on to the household, which is what we would believe because of the greater risk in households."
Air New Zealand has confirmed there is no impact to its trans-Tasman flight schedule as a result of the new cases.
"From today all flights from Sydney to New Zealand will operate with additional passenger health screening in place prior to boarding at the request of the New Zealand Ministry of Health," a spokesperson said.
"The screening asks whether the traveller has recently been in any locations of interest in New South Wales."
