One man's non-disclosure equals coronavirus isolation for another 400 people.
That's the worrying arithmetic in Shepparton as the northern Victorian town deals with the outbreak that has infected three people so far.
The man, a Melbourne truck driver, has been referred to Victoria Police after he initially failed to disclose he had visited Shepparton on September 30.
It only came to light earlier this week after the first of the three infected people went for testing.
That has left health authorities scrambling to contain the virus spread.
"I would again just make it clear that we have got about 400 people in the Shepparton community that are either cases, contacts or their contacts, so those are three separate groups of people who are all linked through potential chains of transmission," Premier Daniel Andrews said on Thursday.
"They are isolated at home... because of one person."
Shepparton and surrounding towns are heading into the third day of their testing blitz, with long queues at test sites on Wednesday and Thursday.
Of the 1861 tests on Wednesday, 350 had all come back negative so far and another 2000 tests were expected on Thursday.
The driver, who was infected in the Chadstone Shopping Centre outbreak, previously had admitted to visiting Benalla and Kilmore on September 29 and 30.
He visited the towns on a worker's permit and dined at a Kilmore cafe, sparking an outbreak there.
The truckie also stayed overnight in Kilmore on September 29.
Sources close to the driver told the Herald Sun he was “feeling so much guilt” after he passed the virus on to his “vulnerable father”.
Deputy Chief Health Officer Allen Cheng said the driver had slipped through the contact-tracing net by the time he left for Kilmore.
Long testing queues in Shepparton
The criteria for testing has loosened in the town and has been significantly widened, including the asymptomatic testing of people who’ve visited certain locations in Shepparton.
But that demand has overwhelmed test sites and Mr Andrews has apologised, saying more will be set up if necessary.
"There's absolutely no notice provided here. That's the challenging part of it," he said.
There was some good news for Victoria on Friday – there were only two new cases and no deaths, leaving the state toll at 816 and the national figure on 904.
Melbourne's rolling 14-day new case average had dropped to 8.7, and remains steady at 0.6 for regional areas.
Department of Health and Human Services figures also show the number of mystery cases in Melbourne rose to 17 on Friday.
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