Extended Christmas gatherings in Sydney homes remain on hold despite the halving of newly-reported cases connected to the COVID-19 cluster on the city's northern beaches.
Causing concern for authorities is the creeping spread of the venues visited by confirmed cases, including a hospital in Sydney's upper north shore.
Queensland, meanwhile, will from Tuesday reimpose NSW border checkpoints after some Sydneysiders allegedly attempted to enter the state illegally.
NSW recorded 15 new locally-acquired cases of COVID-19 amid a record haul of more than 38,500 tests in the 24 hours to 8pm on Sunday.
The state recorded 30 new cases in the previous 24-hour period.
Premier Gladys Berejiklian said the 15 new cases were all connected to the northern beaches, taking the size of the cluster to at least 83.
"(But) one day's result doesn't tell us a trend," she told reporters on Monday.
No decisions would be made on coronavirus-related gathering restrictions for Christmas Day until Wednesday - two days before December 25.
"There could very well be developments in the next few hours which causes us to go back to the number of cases we've seen in the past few days," the premier cautioned.
"I would love to be able to tell everybody today what Christmas might look like in NSW or the northern beaches, but we're not in a position to do that yet."
More health alerts were issued for gyms, cafes, restaurants, a nursery and a sports centre across Freshwater, Mona Vale, Newport, Narrabeen and Warriewood on the northern beaches.
Alerts have also been issued for Twenty-One Espresso in Double Bay in Sydney's east, as well as Anytime Fitness in Berowra, the Asquith Golf Club and Aura Threading and Beauty in Hornsby Westfield in the upper north shore.
The Sydney Adventist Hospital in Wahroonga has also informed staff the hospital was visited by a coronavirus-infected person.
Close and casual contacts have been identified, the hospital cleaned and staff Christmas functions cancelled.
Five cases are now linked to the Turramurra Salon for Hair on Sydney's north shore, and two cases to the Rose of Australia hotel at Erskineville.
The government has imposed numerous restrictions on the Sydney region, including the Blue Mountains, Central Coast and Wollongong, which will remain in place until midnight on Wednesday.
People in those areas can have a maximum of 10 in their homes and patrons need to maintain a four-square metre distancing at venues. Up to 300 people are permitted at places of worship and hospitality venues.
On Sunday, northern beaches residents were put into lockdown until midnight on Wednesday and no one can enter or leave the area without a lawful excuse.
Health Minister Brad Hazzard said everyone in Sydney should be wearing masks when shopping, on public transport or when out in the general community, but the government had no plans to make it mandatory.
Opposition leader Jodi McKay implored the government to change tack.
"Public transport is a high-risk situation yet we know how important it is to get people to continue going to and from work," Ms McKay told reporters.
NSW Chief Health Officer Kerry Chant said any decision around Christmas restrictions would be based on the prevalence of COVID-19 outside of the northern beaches, and whether new clusters formed.
"What we're interested in is making sure we don't see any further transmission that is not linked exactly to the Avalon cluster," Dr Chant told reporters.
From Tuesday, NSW will also force international air crew members into police-supervised hotel quarantine arrangements. Those who reside in NSW may self-isolate at home, but only after undertaking a COVID-19 test.
Every state and territory has now moved to block Greater Sydney residents from entry, with some also blocking those in the Central Coast and Illawarra-Shoalhaven.
WA has re-imposed its hard border for NSW residents, while Queensland on Monday declared it would re-establish checkpoints at the NSW-Queensland border.
Queensland Premier Annastacia Palaszczuk said Sydneysiders had been attempting in recent days to enter the state, in contravention of state health orders.