Victoria has recorded 374 new coronavirus cases and three more deaths, as the state's chief health officer says there are encouraging signs restrictions are working.
Premier Daniel Andrews confirmed three women, aged in their 80s, 90s and one over 100, died of the virus overnight, bringing the number of coronavirus deaths in the state to 42 and the national toll to 126.
Two of the women were residents of aged care facilities where outbreaks have occurred.
There are now 3078 active COVID-19 cases in Victoria and 174 people in hospital, with 36 of them receiving intensive care.
Despite the figures being the state's second-worst, Mr Andrews said the cases hadn't been increasing exponentially.
"We're not seeing that absolutely exponential growth, doubling and then doubling again every couple of days. That's not a small achievement, that's quite a significant achievement," he said.
Mr Andrews said it was too early to know whether further restrictions are needed to drive case numbers down. Metropolitan Melbourne and Mitchell Shire entered stage three restrictions almost two weeks ago, on July 9.
Chief Health Officer Brett Sutton said the state's daily case figures have stabilised since Friday, when a record-breaking 428 new infections were announced.
"We are seeing a rollercoaster of numbers and I think to a degree our anxieties do rise and fall as the numbers do, but there has been some levelling in the last four or five days," he said.
"Of the modelling of a couple of weeks ago, if we had been on an exponential curve which is what happens with COVID-19, we would have been thousands of cases at this point.
"We are not, we are at 374. I'm not satisfied with that but it is better than 3000."
Professor Sutton said fewer new cases were being detected in hotspot postcodes and at public housing towers across the city but outbreaks at aged care facilities and hospitals remained a concern.
"There's a mixed bag of good and bad news with different postcodes and different settings across Victoria, but I hope that mask-wearing as a universal setting will make a really significant difference in the transmission risk," he said.
From Thursday, Melburnians must wear a face-covering in public or risk a $200 fine.
The premier said he was pleased to see many people already wearing masks.
"It is heartening to see so many people listening to those messages, changing their normal habits and embedding mask and face covering-wearing as part of just the normal daily routine," Mr Andrews said.
Meanwhile, about 100 healthcare workers will return to work.
A total of 400 have been forced into self-isolation for 14 days after coming into contact with confirmed cases of COVID-19.
The shortage of staff meant both the Northern and the Austin hospitals were unable to take emergency patients overnight.
More than 40 Victorian aged care homes have also recorded outbreaks since the pandemic began, with Health Minister Jenny Mikakos confirming several aged care residents are among the state's COVID-19 deaths in recent days.
New outbreaks have been identified at Iris Manor in Ashburton and Mercy Place in Parkville, which have recorded a single case each, while two cases have been linked to Epping Gardens Aged Care.
A cluster St Basil's Homes for the Aged in Fawkner has nearly quadrupled since Monday to 51 staff and residents, while 42 cases have been linked to Estia Health in Ardeer.
Clusters at three networks across the state have also grown.
Colac Otway Shire's mayor has been calling for a two-week lockdown after 27 people in the region tested positive to the virus. Thirteen of those cases are linked to Australian Lamb Company.
VICTORIA'S WORST VIRUS DAYS:
* July 17 - 428 new cases, 3 deaths
* July 21 - 374 new cases, 3 deaths
* July 19 - 363 new cases, 1 death
* July 16 - 317 new cases