According to NSW Health's Sewage Surveillance Program Young's sample taken on November 22, tested positive, after no traces were found in the sample taken on November 18, however, the previous test on November 15 had returned a positive result.

The sample taken on November 11 was negative, however two samples taken on November 8 and November 4 both returned positive results.

Health authorities agree that it may be people passing through, however they are urging locals with even the mildest of symptoms to come forward for testing as there has clearly been cases in the area.

"Everyone in these areas is urged to monitor for the onset of symptoms, and if they appear, to immediately be tested and isolate until a negative result is received," a NSW Health spokesperson said.

"NSW Health encourages everyone who is eligible to book into a NSW Health vaccination clinic or another provider without delay."

The warning comes as the World Health Organisation listed a new variant of concern coming out of southern Africa that has been named the Omicron variant.

Though not much is known about the new variant at this stage the World Health Organisation listed the variant as a concern after they met on Saturday Australian time.

NSW Health on Sunday confirmed two passengers from the southern African region who arrived in Sydney on Saturday have tested positive to the Omicron variant.

"The passengers arrived on Qatar Airways QR908, Doha to Sydney, which landed around 7pm, Saturday November 27," the NSW Health spokesperson said.

"Fourteen passengers who arrived onboard this Qatar Airways flight are from one of the nine southern African countries of South Africa, Lesotho, Botswana, Zimbabwe, Mozambique, Namibia, Eswatini, Malawi, and the Seychelles.

"These passengers have been transported to the Special Health Accommodation where they will undertake 14 days of quarantine.

"NSW Health is contacting other passengers on the flight considered close contacts to request they get tested immediately, and isolate for 14 days."

NSW Health have updated its information for anyone who has arrived from any of the countries of concern.

"In line with Commonwealth measures, all travelers arriving in NSW who have been in South Africa, Lesotho, Botswana, Zimbabwe, Mozambique, Namibia, Eswatini, Malawi, and the Seychelles during the 14 day period before their arrival in NSW must enter hotel quarantine for 14 days, irrespective of their vaccination status," the spokesperson said.

"All travelers who have been in any other overseas country during the 14 day period before their arrival in NSW must travel directly to their place of residence or accommodation and isolate for 72 hours, pending further health advice.

"All flight crew who have been overseas during the 14-day period before their arrival in NSW must travel directly to their place of residence or accommodation and isolate for 14 days or until their departure on another flight that leaves Australia, consistent with the current rules for unvaccinated flight crew.

"Anyone who has already arrived in NSW who has been in any of the nine African countries within the previous 14 days must immediately get tested and isolate for 14 days, and call NSW Health on 1800 943 553.

"All unvaccinated travelers from any overseas country will continue to enter hotel quarantine."