Victoria's chief health officer has warned the state's 6.5 million people its snap five-day lockdown is likely to only end if new positive coronavirus tests come from people already identified from previous exposure sites.
Professor Brett Sutton said it was key to avoid adding to the list of locations which has ballooned to 38 Tier 1 exposure sites after a 17th case was linked to the Holiday Inn cluster on Monday.
He warned further cases linked to the cluster were likely and told ABC Radio on Monday afternoon it was "critical" any subsequent locally acquired cases were already isolating as contacts of previous cases.
"We're hoping that all of those would occur in people that have already been identified, already been quarantined and would not generate any more exposure sites," he said.
"That's the critical thing. We don't want new cases to emerge where we hear that they've been to multiple public areas or gatherings.
"That's, in essence, the reason for this five-day short, sharp lockdown."
On Monday a further 251 close contacts were identified in connection to case 15 and case 17 of the outbreak, Department of Health testing chief Jeroen Weimar said.
One hundred and fifty of those are contacts from the female identified on Monday, who worked at a psychiatric unit at The Alfred hospital and psychiatric wards at Broadmeadows Hospital and the Northern Hospital in Epping.
All three have been shut down.
The other 151 contacts are linked to her three-year-old child after they attended Glenroy Central Kinder and Goodstart Early Learning Centre in Glenroy for three days last week.
There are 1350 primary contacts linked to the Holiday Inn outbreak in total.
Andrews remains coy over lockdown length
Premier Daniel Andrews told reporters on Monday he could not confirm whether the lockdown would end on Wednesday.
"It's too early for us to say. These are promising results but the more detective work you do, the more people that come into focus," he said.
“I know every Victorian on Monday morning wants to know whether this is going to finish on Wednesday night... I’m not in a position to be able to confirm that."
He did however reassure the state is "well placed".
A list of all exposure sites can be found on the Department of Health website.
Do you have a story tip? Email: email@example.com.