As the end of Victoria's extended lockdown looms, health officials will be assessing the next steps in the state's COVID-19 outbreak, which has grown to 70 locally acquired active cases.

Slowly, health officials and contact tracers are getting on top of the outbreak.

Deputy Chief Health Officer Allen Cheng said we're running "neck and neck" with the virus. 

Investigations are continuing into how a West Melbourne family of four was infected with the dangerous Delta variant while on a camping trip in New South Wales.

Genomic sequencing is being run through a national database to find a match. 

Normally, health officials can get a match on genomic sequencing in 80 per cent of the cases.

"We have theories, and we're working through those so we're looking at people, if you sort of think through it, it's the people that the sequencing wasn't possible," Professor Cheng said.

"So obviously, it's like a fingerprinting database, the people that have had the fingerprints, you can say, they're not the source case."

There are now 10 active cases in the West Melbourne cluster.

Two of the new cases were primary close contacts of a cluster originating in Port Melbourne as well as the West Melbourne outbreaks and were already isolating. 

Three outbreaks of unknown origin

Contact tracers have also linked four previous cases to the Port Melbourne outbreak through genomic sequencing.

Two more cases were revealed at the Arcare aged care facility at Maidstone, in Melbourne's west, including a resident and a staff member.

Luckily the staff member had not been working elsewhere and the infection was discovered through daily testing of staff.

That leaves three outbreaks with unknown sources: the Whittlesea outbreak, which began with the Wollert man who left hotel quarantine in early May; the Arcare outbreak and the source of the Delta outbreak linked to West Melbourne.

Professor Cheng says as time goes on and the virus runs through a 14-day incubation cycle, health officials become less concerned about finding the exact source of the outbreak.

"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, you know, hidden transmission going on after, you know, one to three weeks," he said.

There are still more than 6,000 primary close contacts in quarantine but on Sunday, about 1,900 people were released from isolation after getting a negative test on day 13. 

Will the COVID-19 restrictions be eased?

So what does all of that mean for the end of the lockdown?

"It is a day-by-day proposition. That is our expectation but we don't want to be in this any longer than we need," Professor Cheng said.

"If we can, we would leave early but at this stage our expectation is [to] continue to Thursday."

Acting Premier James Merlino said any decision would be based on sound public health advice, but on Sunday he sounded optimistic.  

"We all want to get through this period as quickly as possible, it will be based on public health advice," he said.

"My expectation is that by the end of this period will be in a position to have a further easing of restrictions."