Australia's top doctor said he would "welcome" high case numbers of Covid-19 in NSW, saying finding positive cases is "the most important thing".
On Saturday, NSW reported 77 new Covid-19 cases, taking the total number of locally-acquired cases to 566 since the Bondi outbreak, which started in June.
NSW Premier Gladys Berejiklian said she would be very surprised if Monday's cases were under 100.
Speaking in Canberra on Sunday afternoon, Australia's Chief Medical Officer Paul Kelly was optimistic about the number of cases NSW was picking up.
"At this point (of the outbreak), I would welcome higher numbers," he said.
"Finding people is the most important thing, finding people quickly and making sure they are not out in the community and potentially spreading it further is the important thing."
However he did concede the numbers were "worrying".
"What we want to see is a decrease in the number of people out in the community and potentially infectious in the community... so that is the important component," Professor Kelly added.
"The fact that they are finding most of the people at the moment being close contacts is also a real demonstration that they are doing that contact tracing and getting to people quickly and that is a positive development."
He also anticipates higher case numbers in the coming days and hopes they will start to fall soon, adding the numbers we are currently seeing reflect what was happening within the community one or two weeks ago.
There are 15 Covid-19 patients in intensive care in NSW, with five on ventilators.
Prof Kelly said one of the six SummitCare Baulkham Hills aged care residents who caught Covid-19 from an infected staff member was "seriously unwell" in hospital.
That person was the only unvaccinated infected resident.
Sydneysiders are now required to wear masks in all indoor areas of construction sites and common areas of apartment blocks.
City-wide restrictions were tightened on Friday afternoon, with exercise limited to groups of two and only one person per day from each household allowed to leave the house to go shopping.
Calls for tougher lockdown
An expert has called for NSW to go into a stricter Covid-19 lockdown after cases soared on Sunday.
UNSW Strategic Health Policy Consultant Adjunct Professor Bill Bowtell AO has called for 'Stage 4' restrictions to curb the mounting cases of Covid-19.
"Unhappily today's figures only reinforce just how serious this is. Stage 4 lockdown required. Non-essential big retailers must close," he tweeted.
Speaking with The Daily Telegraph, Prof Bowtell warned NSW was "heading off the cliff" and in the coming days, there will be more cases, hospitalisations and ICU admissions.
"We are on the edge of the exponential, it is out of control," he said.
Prof Bowtell believes a hard two-week lockdown is what is needed to stop the spread, meaning no non-essential retailers.
"A hard lockdown now will knock it off in two weeks and a hard lockdown is not retailers open," he said.
"The virus moves with people. It could take weeks, or months, to bring under control."
Speaking with the ABC on Saturday, Prof Bowtell said Victoria was the "gold standard state for these things", referring to the restrictions.
He said until NSW had a lockdown like Victoria did, it would be "running behind" trying to stop the spread of the highly-contagious Delta variant.
"We have to stay at home, we have to get tested if there's any sign of symptoms, and we have to buckle down and hunker down," he said.
"It's entirely regrettable. It was pretty avoidable, frankly, but every step of the way politics got over the science."
Victoria shuts border to NSW, ACT
Victoria has effectively shut its border to the entirety of NSW and the ACT over concerns Covid-19 could leak out of Sydney.
The Acting Chief Health Officer has declared NSW and the ACT will become red zones under Victoria's travel permit system from 11.59pm on Sunday.
Previously both regional NSW and the ACT were listed as orange zones, allowing people from those areas to enter Victoria if they got tested and isolated until they returned a negative result.
But Victorian health authorities have decided to reclassify them as red zones after NSW recorded 77 new local cases on Sunday.
"Victorian public health authorities are concerned about the risks of transmission beyond current red zones in Greater Sydney and surrounds, and the potential risks this poses to the Victorian community from people entering our state," a statement read.
Victorian residents can still return from red zones, but must isolate at home for 14 days upon their arrival.
The "bubble" arrangement along the Victorian-NSW border remains intact for local residents, though they must continue to travel with proof of address and not enter any red zones.
"You cannot enter if you have been to a red zone outside of the cross-border area, or if you have Covid-19, any symptoms, or have been defined as a close contact by a state health authority," the health department said.
Victorian Premier Daniel Andrews, who grew up living in Wangaratta near the state's northern border, had earlier flagged the imminent tightening of travel restrictions with NSW.
"We do not want this virus here in our state," he told reporters.
"I would say to all of those Victorians who are in Sydney and in NSW more broadly, if you're coming home then you better be quick about it.
"Many warnings were given about exactly this sort of outcome."
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