As Sydney's eastern suburbs Covid cluster climbs to nine cases, mask-wearing indoors is now mandatory in seven local council areas.
It comes as NSW residents await the announcement of official coronavirus numbers on Monday amid fears of harsher restrictions.
“At this stage, we didn’t want to make the decision to have compulsory face mask wearing across all Greater Sydney but if the situation changes overnight, that is an option we will have to consider,” Premier Gladys Berejiklian said on Sunday.
Anyone shopping, working in hospitality or indoors must wear a mask unless eating or drinking if they live in the local government areas of Randwick, Bayside, Botany Bay, Inner West, City of Sydney, Waverley and Woollahra.
Ms Berejiklian said on Sunday the government would also extend compulsory mask-wearing on public transport in Greater Sydney until Thursday, and expand the order to Wollongong and Shellharbour local government areas.
Late on Sunday, NSW Health released a list of 27 new exposure sites including a North Face outlet in Drummoyne. More causal sites are in Drummoyne along with others at Castle Hill, Merrylands, central Sydney and Hurstville.
Greater Sydney and Blue Mountains residents have been told to avoid non-essential visits to aged care and disability facilities, and if visiting must wear a mask with a limit of two visitors a day.
Two new local cases were reported in the 24 hours to 8pm on Sunday, one of which had been revealed by health authorities on Saturday. The other case is a close contact of the previously recorded case.
Another two additional cases in the southern Sydney shire of Sutherland were recorded after the 8pm deadline. They are both close contacts of previously reported cases.
Authorities are urging people to get tested with even slight symptoms and the premier warned the state was entering a critical period.
"The next few days are critical. We ask people not to be complacent. If cases continue to emerge we will need to go further. We are nowhere near having vaccinated the majority of our population yet," she said on Sunday.
The latest outbreak was sparked when an unvaccinated limousine driver, who transported overseas aircrew to and from the airport, tested positive last week to the highly transmissible Delta variant after visiting multiple venues, including the popular Bondi Junction shopping centre.
Four more Sydney LGAs will become "orange zones" from Monday under Victoria's border permit system, while South Australia has joined Queensland by imposing an immediate ban on travellers from the Waverley Council area.
The West Australian government, meanwhile, is setting up Covid-19 testing clinics at Perth Airport's domestic terminals from Sunday to enforce new conditions imposed on travellers from NSW.
Vaccine rollout on cabinet meeting agenda
Meanwhile there will be one item on the agenda when Scott Morrison chairs an emergency national cabinet meeting on Monday: the Covid-19 vaccine rollout.
The prime minister will chair the meeting via video link from The Lodge, where he is in isolation following his European trip last week.
The meeting was called last week after Australia's health experts decided the AstraZenaca vaccine should now be given only to people over 60, rather than over 50s as was their previous advice.
It followed fresh concerns over extremely rare clotting events following the vaccination, which has caused two deaths among the 3.8 million doses that have been delivered.
It will put extra pressure on rolling out the Pfizer vaccine.
Chief Nursing Officer Alison McMillan told reporters in Canberra on Sunday a vaccine update would be delivered after the meeting.
Acting Victorian Premier James Merlino said the Commonwealth's vaccine rollout was an "absolute shambles".
"We do not have the supply of second doses from the Commonwealth to match the demand for first doses," he told reporters in Melbourne.
Western Australia Health Minister Roger Cook is equally frustrated by supply limitations.
"But we're working with what we've got and WA has been very successful. We have vaccinated a higher proportion of our population than any mainland state," he told reporters in Perth.
For more news from NSW go to our NSW news page.
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