The six-day-old transtasman bubble has suffered its first major setback.
Covid-19 Minister Chris Hipkins last night halted travel between New Zealand and Western Australia after Perth and a neighbouring region went into a three-day lockdown.
The lockdown of Perth and the Peel region came after authorities discovered two people infected with Covid-19 had been in the community for five days, and there were numerous locations of interest, including a pool, eateries, short-stay accommodation and a Qantas flight to Melbourne.
The situation was "emerging and serious", West Australian Premier Mark McGowan said in announcing the lockdown, which began at midnight (4am NZT).
As set out in the transtasman bubble protocols, travel between New Zealand and Western Australia had been "paused", pending further advice from the state government, Hipkins said.
"New Zealand health officials are in contact with their Australian counterparts and are completing a risk assessment."
All passengers on an earlier flight from Perth to Melbourne that carried a passenger later found to have Covid-19 had been contact traced and no one on that flight had travelled on to New Zealand, he said.
Air New Zealand confirmed last night that flight NZ176, due to arrive in Auckland from Perth at 5.50am today, had been cancelled.
Customers could rebook, put their flight into credit or get a refund if they had bought a refundable ticket, a spokeswoman said.
"There are no Air New Zealand services to or from Perth [today]. We expect to be able to provide further clarity on the impact to [tomorrow's] return service [this] afternoon."
The last New Zealand flight to arrive in Perth before the lockdown was NZ175, which landed yesterday afternoon.
Any Kiwis affected should follow the advice of Western Australian authorities, Hipkins said.
The situation in Western Australia was an example of the type of scenario both countries had planned for.
More information would be shared today.
As of midnight last night (WA time) until midnight on Monday, April 26, those in Perth and Peel 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. A Victorian man tested positive in Melbourne yesterday after completing 14 days of quarantine at a WA hotel.
McGowan revealed at the beginning of yesterday's emergency press conference the man might have been infectious for a five-day period in the Perth community.
A pregnant woman and her 4-year-old daughter have also tested positive after their stay in Western Australia. They contracted the virus from an infected couple who had returned from India and were staying in a room opposite them.
Speaking before Hipkins' update, infectious diseases expert Dr Siouxsie Wiles said a key question was whether widespread community transmission had occurred.
If transmission hasn't occurred or been widespread New Zealand would be "very unlucky" to have an infected person among those crossing the Tasman before travel was suspended.
But if New Zealand was going to be cautious, we could ask those arriving from Perth 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.
The risk assessment taking place now would determine what people arriving from Western Australia would need to do, should the travel "pause" be lifted after the three-day lockdown, a spokesman for Hipkins said.
The situation in Perth was 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, Wiles said.
"The responsibilities are on all of us."
Traffic light system
As of Thursday, about 14,500 travellers had arrived from Australia since the bubble began, the Government said in its Covid-19 update on Friday.
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, as the Government is 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.
Premier McGowan revealed at the beginning of Friday's emergency press conference that the Melbourne man who had since tested positive might 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 had 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.
About 100 events that had been planned have now been called off.
As soon as news of Friday's emergency update was aired, Perth supermarkets were swamped by panicked shoppers.
'Our hotels were not built for this purpose'
McGowan said at Friday'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 has 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 had 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 Australia on Friday.
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"; the country recorded 312,731 new infections in just 24 hours on Thursday.