Epidemiologists flown in to support Albury Wodonga Health are mapping out the Border's COVID cases, which are being driven by young cohorts with little vaccination protection.
Youth aged between five and 18 account for 41 per cent of cases in North East Victoria.
The revelation of case demographics comes after a group of medical experts raised their concern about cases in schools.
Albury Wodonga Health chief executive Michael Kalimnios said pop-up vaccination clinics were being organised for schools.
"Most of our cases are under 40, and most of them are either partially vaccinated or are not vaccinated at all," he said.
"The younger cohort, that probably haven't had the opportunity to get vaccinated until relatively recently ... it does seem that's a pretty big driver.
"Obviously, the numbers continue to grow.
"It should be noted, however, that most of the cases are linked to known cases; they're not mystery cases.
"There was a contact at Zed Bar a couple of weeks ago, which obviously had a large cohort of young people (present) - that's been a bit of a spreader event."
Mr Kalimnios acknowledged under-12s were yet to access vaccination in providing his breakdown of cases:
Those aged above 50 comprise five per cent of the 185 cases south of the Murray River that Albury Wodonga Health is managing.
While those figures do not cover NSW, it's understood the demographic profile of Albury's 240 active cases is similar.
"Our COVID-positive clinic is now caring for over 300 patients in the community, and we currently have three patients in hospital ... in a stable condition at this stage," Mr Kalimnios said.
"We do ask people to minimise their movement if they can, just while we're in the situation, so we don't spread the virus.
"There are more than 1200 first-dose vaccination appointments available in our Wodonga clinic - if people haven't got vaccinated, they should book."
Mr Kalimnios said staff coming from Melbourne to support testing clinics, which again reached capacity within hours today, "has helped".
"We've also started to scale back our non essential services ... and we've redeployed those staff into areas like our testing clinic," he said.
"We're still looking at what staff we might be able to redeploy into those clinics to give us a bit more capacity as well.
"We have got some epidemiology resources from Sydney and Melbourne that are now with us, here, and part of their task is to start mapping at a very granular level what the expected spread of COVID will be.
"Hopefully over the next couple of days, we'll get a much better sense of how prolonged this outbreak will potentially be.
"The area of concern for us at the moment is that increasing number of people in our COVID positive clinic, so we are talking to both NSW and Victorian governments about potential support.
"Whilst we're managing currently, as the cases increase, that may be a bit of a challenge for us."
Mr Kalimnios predicted another spike over the festive season.
"The modelling always was that as states open up, we're going to see increased pressure on the health system," he said.
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"We do expect this outbreak to peak in the next few weeks, and then we do expect to have another peak, as a modelling indicates, in the December, January timeframe.
"So we're preparing for that and making sure we can deal with that.
"At the moment, we're coping well with the demand; it is putting stress on our staff and we have almost 100 staff now that are furloughed."
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