Federal Health Minister Greg Hunt admits it is a challenging day for Australia as NSW reported 30 new COVID-19 cases, Darwin went into an immediate 48-hour lockdown and Western Australia reimposed restrictions.
The Northern Territory on Sunday reported four new diagnoses, with the government imposing a 48-hour lockdown for the capital city and some surrounding areas, which followed a positive case of a local miner.
In NSW, total cases have ballooned to 110 after entering into a 14-day lockdown in Greater Sydney area and other areas.
In WA, a woman who visited Sydney and returned home also picked up the virus, prompting increased restrictions including mask wearing indoors.
"I know today is a challenging day for Australians," Mr Hunt told reporters in Melbourne on Sunday.
"We've done this before, we know how to do it. And we will get through it."
He reminded Australians this is a global pandemic, noting that in the UK alone there were 18,000 new cases reported overnight.
Health authorities are continuing to track hundreds of passengers from five Virgin flights on Friday and Saturday which carried people between Brisbane, Melbourne, Sydney and the Gold Coast.
The alert was raised after a Sydney-based flight attendant tested positive to COVID, and was possibly infectious on Friday and Saturday.
NSW Chief Health Officer Kerry Chant said the crew member did not have any symptoms when working those shifts and was unaware of having been a close contact of a worker at Sydney's Marrickville Great Ocean Foods, which has been identified as a transmission hotspot.
The Great Oceans Foods cluster has grown to 11.
"We have texted from the manifest people who have been on those flights, but in case they were text messages that did not get received, I am alerting everyone in the community to check the website and ask them to immediately isolate and get tested," she said.
Premier Gladys Berejiklian praised the early behaviour millions of NSW residents after entering the 14-day lockdown.
"The anecdotal evidence we have today is that people have been compliant and we are deeply grateful for that," she said.
The NT situation was sparked by the positive case of a mine worker at the Newmont-owned Granites gold mine in the Tanami desert, some 540km northwest of Alice Springs.
More than 1600 people in three states have been ordered into isolation after he tested positive.
Chief Minister Michael Gunner said the worker was on a flight to Darwin with 80 other people. There are more than 200 other workers who flew from the mine to Darwin and authorities are still to contact about 20 of them.
Queensland has reported two new local cases, with both people believed to have been active in Brisbane for several days.
An updated list of possible transmission sites has been released on the Queensland Heath website.
Amid fears the contagious Delta COVID variant could spread from Greater Sydney, New Zealand has paused a quarantine-free trans-Tasman bubble until at least Tuesday.
"We understand and respect that and regard that is reasonable under the circumstances," Mr Hunt said.
Most Australian states and territories have imposed travel restrictions and are telling residents not to travel to NSW.
© AAP 2021