Australia's learning how hard it is to put the genie back in the bottle, as New South Wales' delta Covid-19 variant marches beyond that state's borders.
Five states now have active community cases with some form of local transmission: the other four are Northern Territory, Queensland, Victoria and Western Australia.
Sydney now has the largest number of Australians living under Covid-19 restrictions since the pandemic arrived last year. States are closing their borders with one-another.
Greater Darwin, in the Northern Territory, yesterday announced it would go into a snap, two-day lockdown after a case linked to an outbreak in a gold mine exposed more than 1650 workers.
Nine hundred of them are so-called 'fly-in, fly-out' workers who left the mine before the positive result came back some are now in other states and New Zealand's Ministry of Health is checking whether any flew back here.
New Zealanders in Darwin are worried they will have infected others in their previously safe city.
Darwin had never had a lockdown until the state's chief minister imposed a strict 48-hour stay-at-home order yesterday afternoon, starting at 1pm.
Northern Territory's chief minister Michael Gunner says this is the biggest threat the state has faced since Covid-19 began and he cannot rule out more restrictions.
New Zealander Ritihia Neho-Popata, originally from Kaitaia, told reporter Jordan Bond the restrictions are unprecedented.