Mr Fraser said today's new case could be linked to one of the four known household clusters and had been isolating.

"Some really good news overnight," he said.

"We only had one new case which is yet to be confirmed through the department of health, which puts us at 18 cases.

"I was very pleasantly surprised to see that, it is a good result but it probably highlights that we still can't be complacent because we are having lots of people getting tested and it only takes a number of those to come back positive and the situation changes quite rapidly."

He told The Standard he would not comment on individual cases, but said all infections had so far been linked to the same exposure point.

"We know that it's all linked to the one exposure which is then connected across the four households and that explains it as well as we can at the moment," he said.

"I think the transmission occurred before anyone knew, that's as much as I know."

But COVID coordinator Sue Anderton said of 1299 tests conducted yesterday, none had so far been returned.

"Yesterday, we did 1299 tests - not quite 1300 - we're still waiting on the results of those and they should start to come through this afternoon," she said.

"On Wednesday, we did 939 tests and so far 803 test results are back and we're expecting the rest of those back this afternoon.

"So far today, we've tested 575 people at all of our sites and we expect that number to rise significantly throughout the day."

Ms Anderton said wait times for testing were currently upwards of four to five hours.

Mr Fraser said the next two to three days would be critical in terms of how the outbreak would look and residents should still limit their travel as a precaution.

"I'm cautiously relieved because we know numbers can go up and down a little bit," he said.

"I'll be more relieved in two or three days if the numbers continue to stay really low.

"It's a time when we're still in that uncertain time, I'd hate for people to think it's time to come back and flow through, I think the upcoming days and weeks will be very telling for us and like I said yesterday, we'd love for people to come back and utilise Warrnambool, but right at the moment it's time to sit for a little bit and see what happens."

Mr Fraser confirmed the Corangamite Shire household cluster appeared to be contained.

"The Corangamite group of positives we saw earlier and over the weekend looks like it's been very well contained within the one household so that's a fantastic outcome," he said.

"All the tests have come back predominantly - we've still got some from yesterday and the day before - but everything has come back negative."

Anyone requiring hotel quarantine will be sent to Melbourne, Mr Fraser said.

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