A regional Victorian city is going into a seven-day lockdown, as the chief health officer warns the state's latest COVID-19 outbreak is yet to reach its peak.
Victoria recorded 423 new COVID-19 cases and two deaths on Wednesday, including four infections linked to the city of Ballarat, about 120 kilometres west of Melbourne.
The new cases in Ballarat, as well as multiple wastewater detections in the region that have not been accounted for, has prompted the city's return to lockdown.
From 11.59pm on Wednesday, Ballarat residents will be under the same restrictions as Melburnians, with the exception of a curfew.
By contrast, the city of Shepparton, north of Melbourne, comes out of lockdown at 11.59pm, with its restrictions to mirror the rest of the regions, after a local outbreak of the Delta variant was brought under control.
"It's great news for Shepparton, not so great for the people of Ballarat," Premier Daniel Andrews told reporters on Wednesday.
"If we allow it to get away in one part of regional Victoria, it becomes a threat and a risk to all of regional Victoria. We simply can't have that happen."
COVID-19 Commander Jeroen Weimar said testing would be ramped up in Ballarat, while thousands of additional vaccine doses would be sent to the area.
Chief Health Officer Brett Sutton said the lockdown would give the city "the best chance of opening up again in the shortest time possible".
However, Professor Sutton warned the state's latest outbreak, which is largely concentrated in Melbourne's northern and western suburbs, had not reached its peak.
"The modelling and everything we know in relation to our current vaccination coverage would suggest that cases will continue to increase," he said.
He said while the state's COVID-19 cases "seems to have stabilised" in recent days, "the risk of getting to 1000 (daily infections) is real".
"We have to press on with vaccinations at the fastest possible rate," Prof Sutton said.
The state's two deaths are Martin Blight, a 46-year-old call centre worker from Whittlesea, and a Wyndham man in his 70s. They bring the toll from the current outbreak to eight.
Mr Blight contracted the virus at his workplace, Serco in Mill Park, and died in hospital on Monday, two days before he was due to be vaccinated.
The premier said Mr Blight was "an otherwise healthy person" and warned "there will be hundreds and hundreds of stories just like his" if Victoria opened with half the state not yet fully vaccinated.
The state government has committed to giving Melburnians more freedoms, including an extra hour of exercise and an expanded travel limit, once 70 per cent of those eligible have received their first dose.
This is was initially forecast to happen on September 23 but Mr Andrews said the target could be reached as early as Thursday.
He said some rules might be relaxed as early as Thursday night.
The roadmap out of lockdown, outlining the state's restrictions through to November, will be released on Sunday.
Opposition Leader Matthew Guy issued a media release on Wednesday morning in which he criticised the government for "stringing the community along for another week" and called for an immediate end to lockdown.
Mr Guy later clarified he meant Melbourne's 9pm to 5am curfew.
© AAP 2021