Extra support is at hand and state border closures are re-emerging as South Australia enters a critical phase of containing its coronavirus outbreak.
Prime Minister Scott Morrison remains positive Australia will be open by Christmas, as Queensland, Western Australia, the Northern Territory and Tasmania announced broad travel restrictions on Adelaide arrivals.
South Australia's cluster is at 17, with 15 of those in the same family.
The number doesn't include three children who have tested negative but are being treated as cases because they have symptoms and their parents tested positive.
Victoria - marking 17 days without new infections or deaths - and NSW have increased screening for Adelaide arrivals, while WA has re-introduced its hard border for the state.
Anyone who has recently been in SA will be blocked from entering WA unless they can secure an exemption.
More Australian Defence Force troops are on the way to help SA while international flights to Adelaide are paused for the rest of the week to ease the burden on hotel quarantine facilities.
WA and Commonwealth contact tracers are helping the SA teams in a bid to stop the cluster from growing.
SA Premier Steven Marshall says time is of the essence.
"We cannot wait to see how bad this gets. The next 24 hours will be critical," he said on Monday.
The state has re-introduced a range of restrictions, including gyms, recreation centres and play cafes closed for two weeks.
Mr Morrison hopes state border closures will be temporary.
"As soon as South Australia is able to get on top of this I would expect that states would keep on the path that we have set towards Christmas," he told reporters in Melbourne.
Acting Chief Medical Officer Paul Kelly convened an emergency meeting of the nation's key health advice panel on Monday to discuss the SA situation.
He believes authorities will be able to get on top of the cluster.
SA's Chief Public Health Officer Nicola Spurrier urged people to maintain hand hygiene, cover coughs and sneezes with their elbow, and to stay 1.5 metres from others.
"I know that's been difficult to do and an element of complacency has, you know, inevitably, occurred here in South Australia but everybody needs to heed those three messages."
© AAP 2020