Residents from eight south-west postcodes are isolating after being identified as primary close contacts of coronavirus cases.
They include 3280 (Warrnambool), 3282 (Koroit), 3265 (Terang district), 3260 (Camperdown), 3250 (Colac), 3301 (Hamilton district), 3289 (Penshurst) and 3300 (Hamilton). It is not known how many south-west residents are in isolation, or which sites they were exposed to.
It comes as the state government extended Victoria's lockdown by seven days and health authorities scramble to contain the highly contagious Delta variant from spreading to regional areas.
13 new cases were recorded across the state, taking the total active cases to 85. Nine of the new cases were isolating for the entirety of their infectious period.
About a third of the state's primary close contacts are located in regional Victoria, largely linked to the Mildura outbreak.
Lockdown is set to end at midnight on Tuesday, July 27.
Victorian Premier Daniel Andrews said the state had "made good progress" but had a "long way to go".
"So far, the strategy is unfolding exactly the way that we would like it to unfold, but we have had a couple of super-spreader events," he said.
"Whether they are technically termed that but we've had a couple of transmission events where large numbers of people have finished up positive as a result of being in the proximity, being close to others for a very short period of time.
"Some of those stranger-to-stranger issues that the speed with which this has moved through the Victorian community confirms that we did the right thing to lockdown and it sadly confirmed that we need more time."
There will be no changes to general public health rules, apart from amendments in relevance to school children with special needs.
This means the five essential reasons to leave home will remain in place state-wide, including shopping for essentials, exercise, medical reasons or care-giving, authorised work or education and to get vaccinated.
Victorians must also stay within five kilometres of their homes.
Masks remain mandatory indoors and outdoors.
Changes to permits mean there will be no further red-zone travel for the next two weeks, though there will be exemptions on compassionate grounds.
Mr Andrews is expected to make an announcement on payments to businesses tomorrow.
Restrictions are likely to remain until the majority of positive coronavirus cases have isolated for their infectious period.
It comes as 13 new cases were recorded across the state - four were announced yesterday - taking the total active cases to 85. Nine of the new cases were isolating for the entirety of their infectious period.
About 18,000 Victorians are at home isolating.
Mr Andrews previously flagged regional Victoria's early exit from lockdown in his announcement on Wednesday.
But with almost a third of the state's primary close contacts being in regional Victoria, largely linked to the Mildura outbreak, this is unlikely to occur.
Warrnambool and south-west residents can find their closest vaccination centre here.
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