Travel between New Zealand and Perth has been put on hold after the Western Australian state entered an emergency three-day lockdown.
Minister for Covid-19 Response, Chris Hipkins, said travel between New Zealand and Western Australia has been paused, pending further advice from the state government.
He said New Zealand health officials are in contact with their Australian counterparts and are completing a risk assessment.
A flight due to leave Perth for New Zealand later tonight will not take off following Western Australia's decision, and any New Zealanders affected are asked to follow the advice of Western Australian authorities, a statement said.
All passengers on an earlier flight from Perth to Melbourne that carried a passenger later found to have Covid-19 have been contact traced and no one on that flight has travelled on to New Zealand.
Another update will be provided tomorrow, Hipkins said.
"Air New Zealand flight NZ176 from Perth to Auckland this evening has been cancelled due to the three-day lockdown in Western Australia," an Air NZ spokesperson said.
"Customers are being given the option to rebook, put their flight into credit, or receive a refund if they have purchased a refundable ticket.
"There are no Air New Zealand services to or from Perth tomorrow. We expect to be able to provide further clarity on the impact to Sunday's return service tomorrow afternoon."
From tonight, Perth and the Peel region entered a three-day lockdown, with West Australian Premier Mark McGowan saying his state is undergoing "an emerging and serious issue".
The news comes five days after the transtasman bubble began, allowing quarantine-free travel between New Zealand and Australia. It's not yet clear how many New Zealand travellers will be affected by the lockdown.
From midnight tonight until midnight on Monday, April 26, residents must stay in Perth and Peel and will not be able to leave unless they have an exemption.
"There will be four reasons to leave your house," McGowan said. "These are: Work, because they can't work from home or remotely; shopping for essentials like groceries, medicine and necessary supplies; medical or healthcare needs, including compassionate requirements and looking after the vulnerable; and exercise with a maximum of four people, limited to one hour per day."
The snap lockdown follows an outbreak in Perth's hotel quarantine system, with a Victorian man testing positive in Melbourne today after completing 14 days of quarantine at a WA hotel.
That case ended Victoria's 56-day run without a locally acquired infection.
A pregnant woman and her 4-year-old daughter have also tested positive after their stay in WA, having contracted the virus from an infected couple who had returned from India and were staying in a room opposite them.
Transtasman bubble: What happens now?
It's too early to say what the Perth community cases and subsequent lockdown could mean for the transtasman bubble, experts say.
Infectious diseases expert Dr Siouxsie Wiles said the key question is whether there has been widespread community transmission in the Western Australian city as a result of the two community cases.
If transmission hasn't occurred or been widespread New Zealand would be "very unlucky" to have an infected person among those crossing the Tasman.
But if New Zealand was going to be cautious, we could ask those arriving from Perth during the danger period to self-isolate or require them to go into managed isolation - but that must be one which is separate from those used by arrivals from higher-risk countries.
"Ideally hopefully people don't actually need to do 14 whole days in managed isolation."
Anyone coming from Perth who had been to locations of interest relating to the community cases must make that known, Wiles said.
The situation in Perth was also a reminder to Kiwis not to let our guard down - keep using the Covid tracer app, wear masks when required and stay home when sick.
"The responsibilities are on all of us."
Epidemiologist Michael Baker also thought it was too early to say what the response should be.
The system in Australia, as in New Zealand, was designed to manage Covid-19 community cases - short, sharp lockdowns and, when necessary, closing state or regional borders.
"Unless there's a large community outbreak it's a very low risk of an infected person getting on a flight to New Zealand."
Authorities on both sides of the Tasman will be assessing the risk right now, Baker said. There's a low tolerance for risk when it comes to Covid-19, and good reasons for that.
"The situation will evolve over the weekend."
About 8pm, a Ministry of Health spokesperson said: "We are currently gathering information from our Australian counterparts and any updates will be provided in due course."
Perth-Auckland flight due tomorrow
Air New Zealand couldn't be contacted this evening, but according to Perth Airport's website, an Air New Zealand flight from Perth to Auckland is due to leave at 7.45pm local time (11.45pm NZT).
NZ176 is due to land in Auckland at 5.50am NZT tomorrow, according to Auckland Airport.
The flight is the return journey of NZ175, which arrived in Perth from Auckland today at 1.40pm today local time (5.40pm NZT).
The next flight from Auckland to Perth is NZ175 at 10am on Sunday.
At 7.20pm, Air NZ still had flights for sale between Perth and Auckland in both directions. It is, however, unclear if the flights will still take place.
Traffic light system
As of yesterday, about 14,500 travellers have arrived from Australia since the bubble began, the Government said in its Covid-19 update today.
The transtasman bubble is designed to allow Kiwis and Aussies to travel quarantine-free between the two countries.
But the exception to that could be if an outbreak occurs in Australia while you visit. You may then have to enter a managed isolation facility on your return to New Zealand.
The Government has set up a green, orange and red traffic-light system to deal with Covid-19 outbreaks in Australia.
You should be able to continue travelling quarantine-free if a Covid case occurs where authorities think there is a low risk of further transmission, such as if it is a border worker who tests positive.
But if there is a Covid case from an unknown source and that Australian state goes into a short lockdown, flights to New Zealand could be paused for up to 72 hours.
Multiple cases from an unknown source could lead to flights to New Zealand being suspended for a longer period.
If you are stranded by the suspension of flights, you will be on your own, with the Government not planning to provide any accommodation.
That means you should plan to have extra money and emergency contingency options in place.
You should also be prepared in case you need to stay in a managed isolation facility if you are returning from an Australian state that has been in lockdown.
Infected man in community for five days
Premier McGowan revealed at the beginning of this afternoon's emergency press conference that the Melbourne man who has since tested positive may have been infectious for a five-day period in the Perth community.
Running through his movements, the premier said the man, who is in his 50s, arrived in Perth on April 3 on flight SQ223 from Shanghai.
His room at the Mercure Hotel was close to other cases recorded in the hotel – a couple from India and a family from Britain.
On Day 12 of hotel quarantine, he returned a negative test result, and subsequently left quarantine on April 17.
After leaving quarantine on April 17, he stayed with a friend and her two children at their home in Kardinya and went to a Malaysian restaurant. That friend tested positive to Covid-19 this afternoon.
On April 18, the man visited a swimming pool in the southern suburbs. He had a coffee in Leeming, dinner in Northbridge, and then stayed at St Catherine's College (which offers short-stay accommodation) at the University of Western Australia (UWA).
On April 19, he visited a Chinese traditional medicine doctor, went to Northbridge, and stayed another night at St Catherine's.
On April 20, he visited Kings Park and Northbridge again.
On April 21, he had breakfast at St Catherine's and was driven by his friend to the airport. He boarded flight QF778 from Perth to Melbourne at 1.05pm.
Anzac Day services cancelled in Perth
McGowan also announced that Anzac Day services across Perth and Peel have been cancelled.
"I encourage everyone to take part in the driveway dawn service again this year and I will do that again," McGowan said.
Police Commissioner Chris Dawson called this weekend a "precious and collaborative weekend because of Anzac Day".
"It is probably the most important commemorative day for our fallen diggers and all Australians and New Zealanders know how special this is," he said.
Roughly 100 events that had been planned have now been called off.
As soon as news of this afternoon's emergency update was aired, Perth supermarkets were swamped by panicked shoppers.
'Our hotels were not built for this purpose'
McGowan said at today's announcement that Australia's hotels were not built for the purpose of holding returned travellers who could potentially be infected with Covid-19.
"Our hotels were not built for this purpose but that is the only solution we have at this point in time if we're going to have returning Australians," he said.
"We all know Australians want to come home … If Western Australia is going to participate in this, the risk is out there."
For the time being, he's requested from Prime Minister Scott Morrison that the number of Australians returning to WA is halved "so that we can reduce the risk to our state through our hotel system in light of what has occurred".
Despite the raft of changes WA has made to its hotel quarantine system, Covid-19 is "insidious", McGowan said.
Surge in infected returnees
In the past 24 hours, multiple Australian states and territories have seen a dramatic rise in Covid-19 infections in those returning from overseas.
New South Wales and the Northern Territory saw the most significant rise in hotel quarantine cases, recording 18 and 13 infections overnight.
South Australia recorded nine new cases in hotel quarantine.
As a whole, there were 46 Covid-19 cases from overseas travellers recorded across the country today.
NT Health authorities have confirmed all its new cases were discovered in travellers returning from India, prompting further concerns about how the country's growing outbreak could affect Australia.
It comes after Morrison announced international arrivals from India would be reduced by a third as the country deals with an escalating Covid-19 outbreak.
Anyone travelling to Australia from India will also have to take a Covid-19 test before boarding.
The virus situation in India has been likened to a "tsunami", with the country recording 312,731 new infections in just 24 hours on Thursday.
- With news.com.au