Genomic sequencing is being done by NSW public health experts to understand links between the Melbourne coronavirus outbreak and cases in NSW, including those in Albury.
It comes as the Victorian Department of Health and Human Services updated its virus tally for Wodonga, removing the mystery case which was reportedly a person in Melbourne.
On the same day that The Border Mail revealed there had been two positive results returned for people in the Albury-Wodonga region, DHHS listed a new active case for the Wodonga LGA.
That case, included in the July 6 statewide coronavirus update and bringing Wodonga's overall case tally since the pandemic outbreak to two, was removed in the July 10 data update.
No further details about the apparent case in Wodonga were provided by DHHS, with even the NSW Premier, Gladys Berejiklian, referencing the case.
"We can't control what's happened on the other side of the border and I've already had advice this morning that [there is] at least one person from Wodonga who has the virus, we're still awaiting details," she said, during a press conference on July 8 about the border closure.
Albury Wodonga Health chief executive Michael Kalimnios later confirmed the person was in Melbourne, despite his staff not conducting the testing for that case.
The DHHS contact-tracing team records a residential address for all patients who test positive for COVID-19; this may not always indicate that the person was tested locally or that they are currently residing in the local government area.
Confirmation the case was not relevant to the Wodonga LGA means the city has been coronavirus-free since April, when its first and only case was confirmed.
There are three active cases in Albury, which were linked to a visit to Melbourne.
NSW Chief Health Officer Kerry Chant explained on Friday that there were many strains of COVID-19, which could reveal the source of infection in some cases.
She said cases in Albury, Merimbula and Ballina were being compared to cases in Melbourne, and cases elsewhere in NSW.
"In those cases, we'll sequence it [the virus], and what we would expect is that if the predominant strain of virus that's circulating in Victoria is 'this', we might see some ... minor genetic changes," she said.
"That indicates they probably come from the same lineage, but they might have slight differences.
"That's certainly what we've observed - minor differences between the viruses when we looked at the virus from the person from Sutherland who also came up from Victoria, to the Crossroads [hotel] strain."
Demand for COVID-19 testing remains high locally, with 1360 tests performed by Albury Wodonga Health for the period July 3 to July 16.
AWH staff are performing on 100 tests per day this month on average, with average turnaround time being two to four days for results.
AWH pandemic response executive director Sally Squire said the health service continued to work closely with the Murrumbidgee Local Health District to support COVID testing, "including the screening of passenger arrivals at Albury Airport and Albury Railway Station in recent weeks".
"We're all in this together as one community. It is pleasing to see that we have had no new cases reported locally in just over a week and we mustn't become complacent," she said.
"We are asking our community, each and every one, to maintain 1.5 metres physical distancing wherever possible, keep up good hand washing and importantly, if you are feeling unwell, stay home and if you have any signs or symptoms of a cold or flu, please seek medical advice."
Anyone experiencing symptoms, however mild, is encouraged to seek testing with their GP or via the AWH screening clinic on (02) 6058 4444.
The Murrumbidgee Mobile Testing Clinics continue to be stationed in the border region, with mobile clinics in Tocumwal and Albury (at the showgrounds) on Saturday.
Anyone who visited Cafe Borellas on June 30, when an infected traveller was present, is encouraged to come forward for testing, even if they don't have symptoms.
For others with even the mildest of symptoms, the mobile clinics will be at the following locations:
Members of the community can also call the Murrumbidgee COVID-19 hotline (open every day from 7am - 9pm) on 1800 831 099.
The July 17 update from DHHS and the Victorian Chief Health Officer showed there was one active case each in East Gippsland and Great Shepparton, five in Ballarat and 16 in Mitchell Shire, with the vast majority of 428 new cases in the Greater Melbourne area.
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Premier Daniel Andrews urged regional Victorians not to become complacent while Melbourne and Mitchell Shire continued to be restricted by stage three lock-downs.
He has recommended regional Victorians wear masks for the first time, in settings where they cannot maintain social distancing.