Two people have tested positive to the virus in Kilmore, 60 kilometres north of Melbourne, after an essential traveller from Melbourne illegally dined at a cafe in the town.

Some 177 customers of the cafe and their households are now self-isolating.

Wimmera Health Care Group infection control nurse Amy Elliot said the outbreak was a grave reminder to take precautions seriously.

"Wimmera Mallee people need to continue to follow the rules to help ensure there is no further outbreak," she said.

"Now is not the time to become complacent around COVID-19 restrictions, especially in light of another Melbourne outbreak.

"That means surgical masks, or at least 2ply cotton masks must be worn in public at all times, and we still need to maintain physical distancing of 1.5 metres at all times.

Speaking at a regional press conference on Thursday morning, Victorian Premier Dan Andrews said Kilmore highlighted how precarious containing the virus can be.

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"The Kilmore example speaks directly to someone who was actually allowed to travel into regional Victoria but did so, and unknowingly did so with this virus and suddenly we've got literally hundreds of people locked in their homes," he said.

"The virus doesn't discriminate between postcodes.

"If you were to open up more broadly, and that ring of steel was not there, at this stage we know exactly what that would mean."

Mr Andrews also alluded to the possibility regional Victoria could open up further without hitting the milestones outlined in the roadmap.

"As soon as we can map out what any potential future stages look like and timing around that, we absolutely will but safety first, because we don't want to fritter away all the good work that regional Victoria, both families, communities and businesses, have done."

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