“When I look at a two-week period, the number when it gets to 100, that’s when it starts to exponentially take off and head skyward,” she said.
“That’s because of contract tracers having to get to those exposed to a known case.”
Meanwhile, low double figures would give the green light to opening up sections of the economy such as restaurants, cafes and shops – albeit with social distancing rules still in place.
Unlike the current system of six-week lockdowns, restrictions could change more regularly, depending on the number of cases, she said.
Professor McLaws, a pandemic expert who advises the World Health Organisation, said having a defined number would help the public understand why certain restrictions are implemented.
The current alert level could be publicised through an app and in the media, she said, potentially reducing lockdown fatigue and taking the pressure off authorities.
“By identifying a threshold or rule for lockdowns or something like mask wearing or more testing, I think the public will respond very well,” she said.
“We have to build in resilience to the public, they have to understand it will be at least 12 months for a vaccine and not all of us are able to get it because it’s a double dose.”
While some measures could be lifted in coming weeks, it appears likely that compulsory masks will be a feature of Victoria’s pandemic response after the loosening of stage four restrictions.
Epidemiologist Michael Toole from the Burnet Institute said Victorians should keep wearing masks when the current lockdown is lifted.
“The evidence on masks now is stronger and stronger; every new study that comes out shows just how good they are,” he said.
Masks were proven to reduce transmission by about 80 per cent, Professor Toole said.
Public transport, offices and schools were the places where masks would likely be needed the longest, he said.
“I think public transport should be the last to go because you sit in a bus or a train for more than 15 minutes but you may not stay that long in a butcher shop,” he said.
Chief Health Officer Brett Sutton said on Saturday that he expected masks would continue to be worn “for some time” after stage four restrictions are lifted.
He said there would have to be no community transmission before the rule was completely lifted, however he acknowledged that masks may not be required in all settings.
“It’s clear that they’re not always comfortable, they’re not always convenient, but they’re effective,” he said.
Tom Cowie is a journalist at The Age covering general news.