Victoria has recorded six new locally acquired cases of coronavirus today.
It brings the state's active case count to 67 as the number of exposure sites increases to 351.
It comes as health authorities decide on whether to extend Victoria's seven day snap lockdown.
Victoria's Covid testing commander Jeroen Weimar on Tuesday warned at least four of the state's more than 50 locally transmitted cases had come from "fleeting" contact between Victorians.
"What we're seeing now is people are brushing past each other in a small shop ... This is stranger to stranger transmission," he said.
Experts have warned the pandemic is worse today than it was a year ago, with new variants emerging regularly that are more transmissible and resistant to vaccines.
With positive cases continuing in the state, senior ministers met health officials for a "high-level briefing" about the situation and the possibility of extending the state's fourth lockdown.
Officials have not confirmed the extension, but the ABC, Age and Herald Sun have reported the lockdown will carry on beyond tomorrow's deadline.
It is unclear just how long it will last — reports indicate anywhere between three to seven days — but the Herald Sun says "tough restrictions to remain in place until at least early next week".
Regional Victoria is also fighting to stay open, citing no positive cases in country areas.
It says Victorians should expect the five reasons rule to remain in place.
News.com.au has contacted the Victorian Department of Health for comment.
The Age cited a "source close to the government", speaking anonymously because "a final decision had not yet been made".
"Chief health officer Brett Sutton's team was leaning strongly toward recommending a lockdown extension," it reads.
It is expected the decision will be made today, but Victoria's deputy opposition leader Georgie Crozier demanded answers earlier.
"Release the health advice, Victorians deserve info," she said.
NSW Health revealed a positive case from Victoria visited a number of sites, sparking more fears the virus may have spread across states.
'There's more virus in the air'
The worry for officials is how quickly people are becoming infected after just "brushing past" strangers with the virus.
Testing commander Jeroen Weimar said yesterday at least four of the state's 54 locally transmitted cases have come from "fleeting" contact between Victorians.
"What we're seeing now is people are brushing past each other in a small shop, they are going to a display home, they are looking at photos in a Telstra shop," he said.
"This is, relatively speaking, relatively fleeting. They do not know each other's names, and that is very different from what we have been before.
"This is stranger-to-stranger transmission."
Professor MacIntyre told the ABC's Patricia Karvelas the variant spreading in Melbourne is "more transmissible" and "more contagious" and that it has a particular mutation that's "more likely to make it more vaccine-resistant ... so that's a big concern".
"There's more virus in the air, we know that Sars Covid-2 is airborne so an area where someone has been indoors might be more at risk with this particular virus.
"The biggest risk is breathing in the virus through contaminated air indoors, in settings that are poorly ventilated.
"The stakes have been raised with this variant because we know it's more transmissible."
"The pandemic is worse today than it was a year ago and there are new variants emerging regularly. They are particularly more transmissible and resistant to the vaccines we have available, to different degrees, so the stakes are much higher."
Sutton had earlier hinted an extension was likely after describing the spread of the virus as "concerning".
"We've gone from a single case of the beginning of the month to 4200 primary close contacts," he said.
"It has been a rapidly moving virus and the transmission that has occurred in those high-risk settings has been very substantial.
"So we have to take [lockdown] as a day-by-day prospect.
"With more numbers today coming through and those really concerning settings, especially in aged care, we are neck-and-neck with this virus and it is an absolute beast."
Victoria recorded three new Covid-19 cases yesterday.
Health Minister Martin Foley said two of the cases were primary close contacts, who were already quarantining during their infectious period.
The final case is still under investigation.
"They are not a contact and are not are directly linked to any exposure site, but there is very close proximity to other exposure sites and we are confident the investigation ongoing will uncover further crossover," he said.