A new Omicron case has been confirmed as a child in New South Wales who was too young to be vaccinated against Covid-19.
Nine newspapers are reporting the child has been staying with their parents at the Mantra apartments in Chatswood, on Sydney's lower north shore.
The child's parents are fully vaccinated and have both been infected with Covid-19.
Earlier, a new Omicron case was identified by NSW Health following ongoing genomic sequencing of confirmed Covid cases who have recently returned from overseas.
The person arrived on flight QR908 from Doha to Sydney on November 23 and is now isolating in special health accommodation with their family.
Two other members of their household are also confirmed cases of Covid and urgent testing is under way to confirm if they are also infected with the Omicron variant.
"These travellers have not been in southern Africa and NSW Health is concerned transmission may have occurred on this flight," NSW Health said in a statement.
Anyone who was on QR908 from Doha to Sydney on November 23 must immediately get tested for Covid and isolate while waiting for further health advice.
"NSW Health will contact all passengers and flight crew to advise them of their isolation requirements. They can also call NSW Health on 1800 943 553 for further advice," NSW Health said.
The new Omicron case also visited a venue in Chatswood, sparking a full seven-day alert.
Anyone who visited the below venue at the times listed is a casual contact and must immediately get tested and isolate until a negative result is received.
Mantra Serviced Apartments, Chatswood, from November 23 to November 30, all day.
This brings the total number of Omicron cases in NSW to seven and the number nationally to eight.
South Australia changes NSW border restrictions
South Australia has changed the border restrictions for those coming from NSW, as cases of the Omicron variant rise.
"Effective later this afternoon we will be putting further requirements for people coming from NSW to have a test on arrival. This is another way that we will be protecting ourselves," SA Premier Steven Marshal said.
"What I can say is we'll be monitoring the situation, particularly in NSW, extraordinarily carefully. We have been looking at it on a daily basis."
Why Omicron could be a 'blessing'
An infectious disease expert has claimed the Omicron variant is likely already spreading undetected in NSW, though he revealed the new variant could be a blessing in disguise.
Speaking to Sunrise on Thursday, epidemiologist Professor Tony Blakely said it is very likely that cases of Omicron will continue to rise in Australia.
"We do expect case numbers to rise. It has probably got its tentacles into NSW, and it will rise, as it has overseas," he said.
Initial indications suggest the Omicron strain could be more mild than the Delta variant, with Professor Blakely saying this could provide a pathway out of the pandemic for Australia.
"This one should be more mild, but we don't know exactly how much more mild it is, so that means that the hospitalisation rate should be less severe. It might become our get out of the pandemic card," he said.
"This may be a blessing if it displaces Delta and becomes the more mild version, it might help us get out of this pandemic."