Victoria has recorded 79 new locally acquired COVID-19 cases, 60 of which could have been infectious in the community.
Health Minister Martin Foley on Friday confirmed 19 of the cases were self-isolating throughout their entire infectious period.
"With interviews still going on with quite a range of others, we would expect that number to grow over the course of the day," he told reporters.
Fifty-three of the new cases are linked to known outbreaks, with the source of the remaining 26 under investigation.
It brings the total number of active cases in Victoria to 660, with about one in 10 infections based in the regional town of Shepparton.
About 16,000 residents in the region, which has a population of 65,000, are believed to be self-isolating, forcing the closure of food distributors, supermarkets and pharmacies due to staff shortages.
Goulburn Valley Health chief executive Matt Sharp said some local tier-one exposure sites, particularly those involving schools, could be downgraded early.
"In the next 24 to 48 hours, I'm hopeful we might be able to see some of those exposure sites have their tier rating reclassified," he told reporters in Shepparton on Thursday.
Emergency Services Minister Jaclyn Symes said the government was working with supermarkets to backfill staff from nearby regional stores, while 400 food relief packs had been delivered to those in isolation.
The state's deputy emergency management commissioner Deb Abbott and other senior departmental officials have been sent to Shepparton to coordinate relief on the ground, while 70 Australian Defence Force personnel will support testing efforts and door-to-door checks in the region.
Meanwhile, an aged care worker in Echuca, about 70 kilometres from Shepparton, has tested positive for COVID-19.
The region's local MP Peter Walsh said Wharparilla Lodge, a 92-bed residential aged care facility, has been locked down with no visitors allowed.
In a Facebook post, the Nationals MP said Echuca Community for the Aged's chief executive had written to families of residents and visitors saying the worker was fully vaccinated and had been well during their last shift at the lodge on 20 August.
An Aldi in Echuca had been listed as a tier two exposure site on 20 August between 5.10pm and 5.55pm.
Premier Daniel Andrews has pleaded for Victorians not to delay testing.
Over the past week, data shows only 40 per cent of symptomatic cases reported getting tested when symptoms first developed.
There are 37 Victorians battling COVID-19 in hospital, including 14 in intensive care, nine of whom are on a ventilator.
SBS is providing live translations of daily New South Wales and Victoria COVID-19 press conferences in various languages.
