Australia's top medic has commended Sydney's northern beaches community for self-imposing restrictions to stem a coronavirus outbreak, which now numbers 40 cases.
Acting Chief Medical Officer Paul Kelly said the community had begun self-isolating and businesses and places of worship had closed their doors even before Premier Gladys Berejiklian announced the strict lockdown.
Key shopping precincts in the peninsula community are quiet and residents have been seen lining up to get tested.
"It's extraordinary, it's a wonder to watch," Prof Kelly told reporters in Canberra on Saturday.
The official lockdown from Saturday to Wednesday would simply reinforce what was already happening, he said.
NSW has recorded 23 fresh COVID-19 cases in the past 24 hours, bringing the outbreak to a total of 40 cases.
Christmas Day plans across the country have been thrown into disarray as states and territories reimpose restrictions on travellers from NSW.
Northern beaches residents have been told to stay home and face mandatory quarantine if they travel anywhere in the country.
Prof Kelly said the AHPPC - a collective body of health officials from all jurisdictions - was meeting daily again and he was having daily conversations with the NSW chief health officer.
A mystery remains for the state's contract tracers as to how the virus got to Avalon RSL.
Genomic testing has indicated this particular strain of the virus came into Sydney via the US on December 1 but it is not known what infection spread may have occurred between then and December 10 and 11 when it appeared in three locations in the suburb of Avalon.
"There's still a mystery there about how that actually happened," Prof Kelly said.
He encouraged Sydneysiders to download the COVIDSafe app to help with contract tracing.
Prof Kelly pushed back on the idea of speeding up vaccine delivery to Australia in light of the Sydney outbreak, saying the rollout was still on track for March, pending approval of the Therapeutic Goods Administration.
"The rest of the country is doing very well. We don't need an emergency vaccine right now," he said.
Prime Minister Scott Morrison has urged Australians to remain calm as the outbreak right before Christmas ruins festive plans.
Western Australia has ordered all NSW visitors to self-isolate for 14 days, while Victoria requires travellers to carry a permit.
Victorian Health Minister Martin Foley said on Saturday that anyone coming from NSW to Victoria this week who had been in the northern beaches "red zone" would spend Christmas Day in hotel quarantine.
The federal government's latest economic update is based on the expectation all state borders remain open next year.
Prime Minister Scott Morrison insists he us not concerned about the impact Sydney's cluster will have on the budget.
