The last time Victoria recorded more than 300 cases was on 14 August 2020, when 301 infections were logged.
In the 24 hours to Thursday morning, 54,242 tests were processed and 37,604 Victorians received a vaccine dose at a state-run hub.
Premier Daniel Andrews on Thursday said he wasn't shocked by the jump in new infections.
"We are going to see cases go up because this virus is highly, highly contagious," he told reporters outside parliament.
"The key point is to keep those numbers as low as we can - not zero - but to keep them as low as we can so that our nurses have got a fair fight, so that we're not making the job of our nurses even harder."
Mr Andrews said the Burnett Institute was working on detailed modelling, which will forecast the peak of the state's COVID-19 outbreak, how the healthcare system will have to respond and what vaccine uptake will do to slow the spread.
He expects the information will be made public in the coming week.
Under the health department's latest projections, Victoria will reach a total of 18,000 active cases by October 16, which is about 10 times the current rate of infection.
Of those projected cases, 800 will need hospital treatment, including 250 who will require an intensive care bed.
There are about 400 staffed and available intensive care beds available in Victoria daily.
The state can make 1,500 available intensive care beds in the public hospital system if required, though the premier in April 2020 announced $1.3 billion in funds to create 4,000.
Mr Andrews on Thursday said there was an "enormous amount of work" being done to prepare the state's hospitals for a surge in cases.
It comes as all of regional Victoria, with the exception of Greater Shepparton, will exit lockdown on Friday, with cafes, restaurants and bars able to fling open their doors with strict patron limits.
About 200 police officers will be sent to patrol the edges of Melbourne and Shepparton to ensure people do not leave locked-down areas.
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