Sydney is on "high alert" after a new Covid-19 case was detected in Bondi from a "fleeting contact" at Westfield, with Gladys Berejiklian announcing new restrictions for residents.
The NSW premier says there has been one new Covid case that has come about as a result of fleeting contact, and there are new restrictions.
The one new locally acquired case since 8pm last night is a man in his 50s who had been to the Bondi Junction Westfield.
"It appears from CCTV cameras that it could have been a very fleeting contact between the infectious person and this gentleman in Bondi Junction," she said.
She said there are new rules in place.
"In relation to what we are recommending people do in the next few days, we want everybody in greater Sydney and for the purposes of this particular outbreak ... we are excluding ... the Central Coast, Illawarra or Wollongong," she said.
"When we are saying greater Sydney we are sticking to the geographic definition. For the next five days we want everybody to wear masks on public transport to make sure that if the virus is circulating it doesn't spread on public transport.
"In relation to mask-wearing, we are recommending that in all indoor venues in Greater Sydney, and is again strictly greater Sydney excluding Illawarra, Central Coast and Wollongong. If you go to an indoor venue you wear a mask, whether it is a cinema, hospitality or front-line hospitality workers.
"It is not compulsory but we are recommending that especially if you cannot guarantee social distancing especially in those places around the eastern suburbs."
One of the nation's leading epidemiologists says restrictions needed to brought in quickly to control a growing Covid-19 outbreak in Sydney, saying the Harbour City is "in trouble".
There have now been three cases picked up in the city's outbreak after a woman in her 70s tested positive on Thursday. There is also another possible case, a man in his 40s from Sydney's northwestern suburbs.
Berejiklian has not yet flagged any restrictions but warned residents in Sydney's east to be on high alert — after the first three cases were picked up there.
She advised them to avoid gatherings and wear masks while investigations were underway into the source of the infections.
One of them is a limousine driver in his 60s, infected with the Delta strain, whose passengers included international flight crews.
Looking at the cases, the circumstances and the strain that could be spreading in Sydney, UNSW epidemiologist Mary-Louise McLaws says it's time for authorities to take action.
"We're in trouble, now we know the strain is Delta," she told the ABC.
"The restrictions need to be strictly and quickly because this virus has learnt how to be highly infectious and doesn't need a lot to spread.
"It's up to 70 per cent more infectious than other strains, so it's very problematic."
Despite the warnings, the new case northwestern suburbs has not passed the virus onto his three household contacts to date.
However authorities say his test results showed low virus levels and he is not yet linked to any known cases.
"An expert panel convened by NSW Health this evening reviewed the results of additional testing and was unable to rule out the possibility the person had Covid-19," NSW Health said in a statement.
Berejiklian meanwhile has urged those south of the bridge to be on high alert, but stopped short of adding restrictions to gatherings or mandating masks.
"Unless you absolutely have to attend a large gathering, unless you absolutely need to engage in activity of a social nature in next few days, we ask everybody to refrain from that," she said.
"Assume that everybody you're in contact with has the virus and assume you have the virus yourself and that's the best advice we can give you as the next few days unfold."
As residents await to see whether any new cases have been picked up in the past 24 hours, questions are being asked about how Sydney is in the situation yet again.
Many are asking why the original case wasn't vaccinated and whether necessary infection controls were in place while he was transporting the international aircrews.
All drivers transporting international aircrew are required to be tested for coronavirus every day, however it was revealed the driver's first time being tested was on June 15.
This has left NSW health authorities frantically "putting the pieces of the puzzle together", prompting others to question whether the current infection control were enough to protect the community.
Dr Greg Kelly, who works at the Children's Hospital at Westmead in Sydney, took to Twitter to air his frustration at the current measures in place for quarantine workers.
"This latest NSW leak 100% preventable. Australia, all that is standing between airborne #COVID-19 & frontline workers (and therefore you, grandma & the rest of us) is a flimsy surgical mask," he wrote.
"No airborne PPE, no smart workplace engineering, & no vaccine. THIS JUST ISN'T GOOD ENOUGH."