It has been confirmed the Omicron COVID-19 variant arrived in New South Wales earlier than previously thought, after a new case of the virus strain was confirmed today.

NSW Health confirmed the new infection, a child, and their COVID-positive parents arrived on flight QR908 from Doha to Sydney on November 23.

Previously, it was believed the virus had only arrived in Sydney on November 25.

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Urgent genomic sequencing is underway to confirm whether the child's parents also have the variant.

The child is isolating in Special Health Accommodation with their parents.

The child's age meant they could not be vaccinated.

Authorities are concerned the travellers caught the virus on the flight as they have not been in southern Africa.

Health authorities are now urging every person who was on flight QR908 from Doha to Sydney on November 23 to get tested and isolate while waiting on further health advice

New exposure site alerts are also in place for venues visited by the family.

Anyone who attended the following venues is now a casual contact.

• Mantra Serviced Apartments in Chatswood from Tuesday November 23 to Wednesday December 1.
• Vodafone, Westfield Shopping Centre in Chatswood, Wednesday November 24 12.25pm to 12.40pm
• Centrelink and Medicare, Chatswood, Wednesday November 24 1pm to 2.30pm
• Priceline Pharmacy, Chatswood Interchange, Wednesday November 24 1pm to 1.10pm
• Woolworths, Chatswood Interchange, Wednesday November 24, 1pm to 2.30pm

If you attended at these times, you must immediately get tested and isolate until a negative test result is received.

It comes as authorities are retesting thousands of COVID-19 swabs for the Omicron variant.

NSW Health will check 2000 positive COVID-19 swabs from recent weeks for signs of the variant.

https://twitter.com/NSWHealth/status/1466236101283090432?ref_src=twsrc%5Etfw

This is to determine how long Omicron has been circulating in the state.

NSW Health Minister Brad Hazzard said pathology has already retested 500 swabs from people who have arrived from southern African countries in the past two weeks.

"They have now completed 500 cases that have come into NSW since the November 22 and they've gone right back through the pathology and I'm pleased to say at the moment none of those proved to be positive to Omicron," he said.

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It comes after a man in south-west Sydney also tested positive to the variant yesterday.

The fully vaccinated man had recently visited southern Africa and arrived on flight QR908 from Doha to Sydney on November 25.

He was on the same flight as the Central Coast woman who tested positive to Omicron on Tuesday.

The man had spent the last six months in Nigeria, which is not one of the eight African countries subject to the border closure issued on Saturday.

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All passengers on the QR908 Qatar Airways flight have been directed to get tested and self-isolate for 14 days.

So far, only one of the eight Omicron cases in Australia is not in NSW.

The eighth is a case in quarantine in Howard Springs in the Northern Territory.