Victoria's growing coronavirus outbreak "will get worse before it gets better", the chief health officer has warned after the state recorded 75 new cases on Monday.
Chief Health Officer Brett Sutton said he expects to see "at least" as many positive cases in the coming days as test results pour in.
A testing blitz is underway in the suburbs of Albanvale, Broadmeadows, Brunswick West, Hallam, Fawkner, Keilor Downs, Maidstone, Pakenham, Reservoir and Sunshine West, which have seen high levels of community transmission in recent weeks.
More than 50,000 Covid-19 tests have been done in the suburbs and Professor Sutton wants to see the results before deciding on any further measures to contain the virus.
Putting the suburbs into a second lockdown remains an option.
"It is absolutely an option and we flagged the possibility of using it and we will use it if it is required," Professor Sutton said.
Monday's increase is the fourth-highest daily total for the state since the beginning of the pandemic.
The last time more than 70 new cases were recorded in Victoria was on March 31, when the state was in its strictest lockdown stage.
Professor Hamish McCallum from Griffith University said the state is experiencing a second wave of the virus.
"The question is whether it is a ripple, or the start of a tsunami," he said.
"In addition to the increased testing, I think there is a case to lockdown the hotspot suburbs."