Victoria will review airflow within quarantine hotels and change mask policies for staff as it seeks to avoid a repeat of two suspected COVID-19 leaks.
Emergency Services Minister Lisa Neville, overseeing the revamped program, announced a ventilation review of all hotels within the system was underway.
"We don't think at this stage this is about ventilation, but again we're not leaving any stone unturned," she told reporters on Saturday.
From Thursday night, hotel quarantine staff were also required to wear a face shield and surgical mask.
Ms Neville said the change was based on updated advice from infection prevention control experts, with hotel quarantine workers previously wearing just N-95 masks.
They will still don the more protective N-95 mask along with a face shield for encounters with infectious guests and when entering rooms for medical emergencies.
In addition, hotel quarantine organisers have put "buffers" between family groups and other guests from Wednesday, resulting in 140 rooms being taken out of the system.
Food delivery times are also being staggered, reducing the risk of people opening doors at the same time.
The moves follow a case of suspected COVID-19 transmission among two separate groups of guests at Melbourne's Park Royal Hotel, and a worker at the Grand Hyatt testing positive to the virus.
Victoria recorded no new local COVID-19 cases on Saturday as all 17 household and social primary close contacts of the hotel quarantine worker infected with the mutant UK variant returned negative tests.
Health Minister Martin Foley was reassured by a strong testing figure of 23,000, but warned the state isn't out of the woods yet.
"I want to reinforce the message that this is not over," he said.
"That this wildly infectious - particularly now we know it is this mutant new case strain - continues to be highly infectious and a real risk to all Victorians."
Chief Health Officer Brett Sutton said officials wouldn't feel comfortable the state was in "safe territory" until the end of the 14-day incubation period.
"A zero day is a great day any day," he said.
"But in particular with this strain, first identified in the UK, having no positive results out of those exposure sites and numerous primary close contacts is very encouraging.
"There is a bit of luck, a bit of randomness involved in the fact that no cases have been identified."
A further 1200 secondary contacts have also been identified including 507 tennis players, officials and support staff.
The entire tennis contingent has returned negative results, paving the way for the tournament to go ahead as planned from Monday.
In line with restriction changes on Wednesday, the Victorian government clarified its mask policy for tennis spectators on Friday night.
When the roof is closed on the main courts of Rod Laver Arena, Margaret Court Arena and John Cain Arena, fans must wear a face mask.
"These venues are deemed to be indoor spaces under the restrictions and masks use is required by all spectators and officials," a government spokesman said.
Spectators can doff masks when the roof is open, while players are exempt from the rule.
Meanwhile, Victoria has downgraded Perth and the WA's South West and Peel regions from a "red" to "orange" risk zone to coincide with the end of its five-day lockdown.
There are currently 22 active cases of COVID-19 in Victoria.
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