A third coronavirus case has been linked to the Australian Lamb Colac cluster.
Contact tracing from Colac's two other active cases led to the detection of the case.
The third case is not a student of the school but is a close contact of the initial case.
Victorian Health Minister Jenny Mikakos said in a press conference on Saturday afternoon that it has not yet been determined how the original Australian Lamb case was contracted.
"We are aware of the risks in this particular industry, we know that the refrigeration at these facilities can create an additional risk," she said.
"We are working closely with the facility and will consider testing across the sector."
Two cases of coronavirus have been linked to a south-west cluster.
Trinity College Colac principal Paul Clohesy said on Saturday morning one of their Year 12 students tested positive to COVID-19.
It comes after the student's parent, a worker at Australian Lamb Colac, returned a positive COVID-19 test yesterday.
"We started a deep clean of the school yesterday and hope to reopen on Tuesday, depending on how long contract tracing takes DHHS," he said.
"I think we are all a bit worried but Colac Area Health jumped on it straight away and their testing response has been as good as could be expected.
"It certainly wouldn't be good if there was a cluster in town, it would impact a lot of families, but we're just hoping that's not the case."
The student left school immediately today to be tested after their family member received a positive result.
"All students are asked to be mindful of their movements over the next few days and to follow the usual social distancing and hygiene protocols," Mr Clohesy said.
"I understand this news will be concerning for many of you. I want to assure you we are doing everything we can to contain and slow the spread of the virus, and ensure the health and safety of our whole school community.
"The school will update all families once the contact tracing has been completed and a decision about reopening the school facilities for students is made."
Colac Area Health will open its COVID-19 testing clinic this weekend but is urging residents wanting a test to ring ahead.
If you wish to be tested please call the Colac clinic on 5232 5402. There are also pop up testing clinics in Lorne -5289 4300 and Apollo Bay-5237 8500.
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