A move to stage four restrictions in regional Victoria hasn't been "ruled out", but Premier Daniel Andrews said it will depend on further testing and tracing.
The renewed testing push in Ballarat, as well as other major regional cities, will provide that data, he added.
"We've always tried to be as open as we can and say it's the numbers that will drive us," he said during an online media conference with regional news outlets.
"That's why we've done this testing push, and I think we'll see thousands more tests in Ballarat, Bendigo, and Geelong.
"It's not as an academic exercise and find out how much virus is here, but also it means every person we test we're able to track and trace, keep them away from other people, and hopefully pull it up and keep those numbers relatively low."
On Friday Ballarat's active case count reached 25, the premier said. Full case numbers will be released later this afternoon.
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Mr Andrews said regional numbers were remaining "relatively stable" in aggregate terms, but the challenge is mystery cases - if authorities are accurately able to trace cases and control them, there will be less need to move to stricter measures.
"I certainly can't rule out the need to change rules in the future," he said.
"We're doing everything we possibly can to avoid having to put any additional rules in place, but that's from our part, the message, the ask is, if you've got even mild symptoms, come forward and get tested.
"We've just got to keep a really close eye on this, and get more information to look at, and that's where that testing push comes from."
Mr Andrews also commented on further restricting movement between Melbourne and Ballarat, following Ballarat Health Services announcing students cannot complete clinical placements at BHS unless they remain in a stage three zone for their entire clinical placement as the health service tightens its COVID-19 controls.
"There's things we can do that are not so much about messaging but about making different choices and putting different arrangements in place," Mr Andrews said.
"For some previously unavoidable movements, we can do that differently - the notion of if you come you have to stay, I don't have much more than that.
"We monitor it every day, we monitor through those chains of transmission and the coronavirus detective work to work out where cases have come from, where they've seeded from, and we're doing everything we can to limit movement.
"I wouldn't rule out further steps about trying to curtail movement, because logic tells you if people are making trips that aren't absolutely necessary, there is a risk they can be bringing the virus with them and not even know, that's the other very challenging part of this."
It is now 14 days since movement restrictions were put in place on visitor movement Moorabool, Golden Plains and greater Geelong, and 10 days since stage three restrictions were reintroduced.
Mr Andrews was asked if the restrictions were working if cases continued to rise.
"We'd need to analyse data in detail," he replied.
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"There are challenges with the sheer amount of movement that occurs for best of reasons, it's not a matter of people doing things that they choose to do, it's people getting to work and all those things they have to do.
Ultimately, certain measures will have impacts, it's very difficult to measure what those impacts were - they don't all land on 14th day, sometimes they're kind of cumulative and takes a while to get a complete picture.
"Almost certain, if we'd not taken those steps, you'd have many more cases."
Remember to always maintain good hand hygiene, wear a mask when in public, and keep a 1.5 metre distance from others at all times.
Right now there are only four reasons to leave your home in Ballarat during stage three restrictions: care and caregiving, local exercise, shopping for necessary items, and for work or study if you are unable to do so from home.
Victoria Police are enforcing restrictions, and penalties apply.
Anyone with the slightest symptoms is urged to get a test immediately, and must self-isolate until results come back - phone 4311 1571 to make an appointment.
Testing in Ballarat is available at the Ballarat Respiratory Clinic on the corner of Merz Street and Eleanor Drive in Lucas, or the Community Health Respiratory Clinic at Ballarat Senior Citizens Centre, at 16 Little Bridge St, Ballarat.
For more information, visit the Victorian Department of Health and Human Services website, or phone the hotline on 1800 675 398 for advice if you are displaying symptoms.
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