As Victoria waits confirmation it will end its seven-day Covid lockdown on Thursday, an epidemiologist says there are two major factors that could affect the decision.
Health authorities have refused to comment on whether or not they think the lockdown will end as scheduled on Thursday, with Chief Health Officer Professor Brett Sutton saying 'we have to prepare for anything' and Acting Premier James Merlino warning the situation 'could get worse'.
As the coronavirus outbreak in Melbourne reached 54 cases on Tuesday, genomic testing showed that most of them were connected to the leak in South Australia’s hotel quarantine system.
However a connection to that original case remains unclear as a new case emerged on Tuesday with authorities yet to determine its source.
Two critical factors to end lockdown
Epidemiologist at the Burnet Institute, Professor Michael Toole, told 3AW on Tuesday morning there were two critical factors that would affect whether lockdown would be lifted at the proposed time on Thursday.
“First, will there be any new so-called mystery cases? These are cases that aren’t obviously linked to previous cases,” he said.
“That would be a worry. I think that would be a reason to prolong this lockdown.
“The other … that concerns us all is aged care homes. Will there be any new cases in aged care homes?
“I think all of us in Melbourne have pretty bad memories of last year when the virus spread through aged care homes with such a terrible death toll.”
As new cases linked to aged care homes emerged on Monday, health authorities said on Tuesday the aged care staff member who worked at two different facilities before testing positive has so far not led to any more cases.
There have been no more cases detected in aged care but concern remains over an unlinked case found in a worker on Sunday.
Professor Toole told 3AW it was concerning aged care workers were employed across different facilities, but said it was promising case numbers hadn't "exploded".
On Tuesday Victoria's Covid testing commander Jeroen Weimar said there are no mystery cases as all cases to date as every cases to date has been linked to the Whittlesea or Port Melbourne outbreaks, or the Arcare Maidstone aged care facility cases.
Concern over 'stranger transmission'
Victoria reported nine new cases of coronavirus on Tuesday, six of which however were announced on Monday.
Health Minister Martin Foley confirmed two of the new cases are close contacts of people who have already tested positive and have been self-isolating.
The remaining case is under investigation. Mr Weimar said that case lives near Stratton Finance in Port Melbourne, where a number of positive cases worked.
"He has exposure from the number of coffee shops around there also frequented by Stratton Finance employees ... that appears to be enough to get the infection across," he said.
Mr Weimar said there have been at least four instances of "stranger to stranger transmission" in this outbreak.
"People are brushing past each other in a small shop, they are going to display homes, they are looking at phones in a Telstra shop," he said.
"This is very, relatively speaking, fleeting contact. They do not know each other's names and that is very different from what we have seen before."
Mr Weimar urged anyone who visited busy shopping centres listed as exposure sites, including Craigieburn Central Pacific Epping, Epping North shopping centre and Broadway Reservoir, to get tested.
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