Victorian authorities say the next two days will be crucial to confidence that they might finally be getting on top of the state’s latest COVID outbreaks.

Victoria had 11 more coronavirus cases on Monday, including two linked to aged care and already announced on Sunday.

Despite the worrying return to a daily tally in double figures – as millions of Melburnians wait to learn whether the city’s extended lockdown will end on Thursday – state authorities say there are positive aspects to the latest infections.

The most positive is that all are linked to one of the clusters that sent the city into lockdown. They were:

• Three household contacts in the Whittlesea outbreak, taking it to 32;
• Three at Arcare Maidstone – one resident and two staff (the resident and one worker’s infections were confirmed by Arcare on Sunday). That cluster stands at nine;
• Four household contacts – three children and an adult – of the West Melbourne outbreak of the Delta variant of the virus. That outbreak has risen to 14;
• One case linked to the Port Melbourne cluster. It is a cleaner from a worksite in Melbourne’s CBD.

Authorities have again refused to be drawn on whether Melbourne’s lockdown will end on Thursday. Photo: AAP

Monday’s figures came from 24,265 tests in the previous 24 hours. There were 17,719 vaccine doses administered in the same period.

Melbourne’s extended lockdown is due to end at midnight on Thursday, although there is yet to be confirmation that will go ahead.

Chief health officer Brett Sutton refused to speculate about lockdown plans on Monday.

“We make those decisions on a day-by-day basis. I don’t know what today will bring in terms of new notified cases,” he said.

“[But] nine of 11 cases are effectively in quarantine.”

Authorities remain concerned about the speed of the virus’ transmission in the latest outbreaks. The West Melbourne cluster has spread from a family of four to a total of 14 cases in five days.

“It is a pretty rapidly moving leading edge that is not the serial interval for all transmissions for that virus,” Professor Sutton said.

“It does mean we are racing against the clock.”

Victorian testing commander Jeroen Weimar said the three new cases in the Whittlesea outbreak had been picked up on day 13 testing in quarantine. They will remain in quarantine.

The new cases in the West Melbourne cluster, whose origins remain a mystery, were also already in quarantine.

There are new exposure sites for the construction site cleaner, including suburban train routes, and the Arcare staff. All of Victoria’s current exposure sites can be found here.

Professor Sutton said it was “good news” that there hadn’t been a further significant bump in exposure sites.

“That is something I’d expect to see more and more of as days go by,” he said.

“It’s early days still. It’s frustrating. People want to know what things will look like three days from now. We see different changes every day and they can be something from left field … we need to see it play out.”

Mr Weimar said nearly 500 close contacts from the Queen Street construction site were in isolation, and 90 per cent had returned negative COVID tests.

Across Victoria, more than 5800 people are still isolating as a result of the most recent outbreaks. More than 1000 were released on Monday, after negative day 13 tests.

“The next two days, it will be important for us to assess if there is any other potential change of transmission to make sure got that outbreak fully under control,” Mr Weimar said.

“Let’s use today and tomorrow to make sure if you have any symptoms whatsoever, please come out and get tested now, it’s really important we wrap our hands around this so we can move forward with some more positive decisions.”

On Sunday, deputy chief health officer Allen Cheng said as time went on and the virus’s 14-day incubation cycle ran out, officials became less concerned about finding the exact source of some of Melbourne’s mystery outbreaks.

“I think it’s fair to say that, with the passage of time, we get more comfortable with unknown source cases if they haven’t transmitted or there’s no hidden transmission going on after one to three weeks,” he said.

Only 2-3 per cent of Victorians have so far been fully vaccinated.

On Monday, state Health Minister Foley said 40 per cent of all COVID vaccinations given in Australia last week were in Victoria.