NSW Premier Gladys Berejiklian has dropped a major hint Sydney's lockdown could continue into next week.
Sydney recorded 35 new cases on Monday — an equal daily high for the state's coronavirus update — and 18 new cases overnight.
The lockdown impacting Greater Sydney is due to end at 11.59pm on Friday, July 9, but Berejiklian told reporters this morning the lockdown "is having its desired effect to date ... but it is still concerning that a number of cases are remaining infectious in the community".
Berejiklian said a decision on the Greater Sydney lockdown will be announced tomorrow morning but warned Sydneysiders that the Delta variant of the virus plaguing the city "is different to what we have experienced" and required "a different type of response".
"If you look at other jurisdictions around the world, we can see that you can't afford to let this get away from you. While we have the best contact tracers in the world, and I believe the right settings at the right time for our population, we have to be mindful that what we are experiencing with this strain is something new during the pandemic," she said.
"NSW wants this to be the last lockdown until we get the majority of our citizens vaccinated," Berejiklian said. "The difference now to what occurred in the last year or so since we had the only other lockdown is the Delta strain."
Berejiklian rejected the notion, put to her by a reporter, that a lockdown decision had already been made.
"The NSW government's priority is always keeping the community safety first and foremost, but also having a keen eye on opening up the economy as well," she said. "It is that balanced approach we will take into our decision-making."
Warnings against ending lockdown
An epidemiologist has warned New South Wales could see another rise in Covid-19 cases if the lockdown is lifted before the state reaches a critical figure.
While the number of people spending their infectious period out in the community is dropping, University of Melbourne epidemiologist Professor Tony Blakely said that figure needed to be at zero before Greater Sydney can safely emerge from lockdown.
"For a lockdown to be successful, we really need to see the number of notified cases that are out in the community down to zero," Blakely told the ABC.
The two-week lockdown for Greater Sydney, the Blue Mountains, Central Coast, Wollongong and Shellharbour is set to end at 11.59pm on Friday, July 9.
However, Blakely said lifting the lockdown while there were still infectious cases popping up in the community could see the outbreak "take off" once more.
"If we just open up restrictions at that point, they will just take off again … that's just how the virus behaves," he said, adding it's not only a risk for NSW, but the rest of Australia as well.
He said if he was in the shoes of chief health officer Dr Kerry Chant he would be a "bit worried" that the numbers weren't dropping.
A team of economists, public health experts and modellers from the Australian National University have also found the benefits of lockdowns that were long enough to get community transmission to zero outweighed the short-term gains of easing lockdowns too early.
"Our key insight was that lockdowns need to be long enough to crush the virus, and that effective, longer lockdowns benefit both public health and the economy," lead author Quentin Grafton said in a statement on Monday.
Decisions must be based on the facts on the ground such as the number of new cases, links to known chains of transmission, and the number of new cases not already in self-isolation, he said.
"The point is to go early [with a lockdown] and go hard and go significantly long enough to bring about zero Covid-19 community transmission. The numbers aren't looking good for Greater Sydney at the moment."
Grafton stopped short of calling for the lockdown to be extended, but said a decision should depend on the data available on Friday.
"We've got to make sure that we get on top of this and we don't get an epidemic."
The virus would not just stay in Sydney, which meant the whole country could be at risk and it would cost hundreds of billions of dollars, he said.
Tom Kompas, from the University of Melbourne, said authorities should rethink how Covid-19 outbreaks were managed.
"We're a long way from a post-Covid world. If we think we can do away with periods of movement restrictions when uncontrolled outbreaks occur, we need to think again.
"The key point here is not to think about the economic costs over a period of a couple of weeks, large as they are, but rather to consider the costs over a period of months if community transmission continues."
On Monday, Berejiklian said the next few days would be "critical" in deciding whether the lockdown will end on time, urging residents to follow the restrictions.