Christchurch residents will be holding their breath in the coming days, hoping the city isn't plunged into level 3 lockdown after it recorded its first Delta community cases.
The Government has so far kept the city in level 2, holding off calling a snap lockdown due to early information indicating that the two Covid cases had little close contact with others.
The cases raise questions about whether travel restrictions between the North and South Islands are tough enough after one of the cases flew home from Auckland.
It also highlights the challenges around vaccine mandates and whether unvaccinated people can be prevented from boarding flights taking them home.
Christchurch Mayor Lianne Dalziel called the new cases a "wake-up call" and a "lucky break".
"It's really good news that we are staying at level 2, but it's a big reminder, a wake-up call for everyone in Christchurch," she said.
South Island residents have so far enjoyed one of the most charmed lives anywhere in the world since the pandemic began last year.
The South has only had one Covid community case during this latest Delta outbreak at a time when Aucklanders have been stuck in their homes in lockdown for the past 10 weeks.
That solitary case was found in Blenheim last week in a person who flew back from the North Island - yet so far that case has not led to any more infections in the community.
Before that the South Island's previous Covid community case occurred more than a year ago.
However, Covid Response Minister Chris Hipkins said the Delta variant is now in New Zealand to stay, and if it doesn't spread with the current Christchurch cases, it is only a matter of time until it returns to the city.
On this occasion, the virus got into Christchurch when one of the new cases flew home from Auckland.
That person had earlier travelled to Auckland to provide childcare - a permitted activity under level 3, if no other person is available.
They returned a negative Covid test, before both their trip to Auckland and their trip back to Christchurch on October 15.
The second Covid case lives with the first person and is a truck driver, who spent four days at work during their infectious period, Hipkins said.
The two new cases then became unwell and returned positive results to their October 26 Covid tests.
There have so far been nine close contacts identified in three houses - all are now isolating.
There are also nine initial locations of interest spread across Christchurch, at a supermarket, takeaway outlets and multiple dairies.
Mayor Dalziel said pushing ahead with vaccinations is crucial.
Canterbury DHB is having a successful vaccination campaign, with 89 per cent of eligible residents having had their first dose.
However, the city is lagging in second dose vaccinations, with just 68 per cent of eligible residents double-jabbed.
She also urged residents to wear masks and scan into businesses using the Government's Covid Tracer app after it was revealed the new cases hadn't been using the app.
Prime Minister Jacinda Ardern, meanwhile, said Christchurch wouldn't necessarily move into level 3 restrictions if more cases are found.
So far contact tracers had been able to get a good understanding of all the locations visited by the two new cases, and this combined with the city already being in level 2 gave the Government confidence the outbreak could be contained.
However, if new cases were found that couldn't be easily linked to known cases, more restrictions may be needed.
Ardern also said the new outbreak showed the complexity of vaccine mandates.
The Christchurch Covid case who flew from Auckland is unvaccinated.
Meanwhile, the New Zealand International Film Festival's opening has been postponed to next Friday.
It was originally meant to begin in Christchurch today.
Festival organisers say they decided to postpone the festival by one week following Covid's arrival in the city.
Christchurch was chosen to open the festival after it was cancelled completely in Auckland.
Christchurch locations of interest
• The Mad Dairy Hornby - October 18 (12:45 PM - 1:15 PM)
• Hornby Chinese Takeaways - October 18 (12:45 PM-1:30 PM)
• Burger King Curletts Rd Sockburn - October 18 (4:30 PM - 5:30 PM)
• Z Curletts Rd Sockburn - October 18 (5:00 PM - 5:30 PM)
• Supervalue Fendalton Village - October 18 (6:45 PM - 7:45 PM)
• Try's Bakery Islington - October 20 (7:30 AM - 8:30 AM)
• Caltex Blenheim Road Riccarton - October 20 (5:45 PM - 6:15 PM)
• Gloucester & Stanmore Corner Dairy Linwood - October 20 (6:00 PM-6:30 PM)
• Pannell Discounter Wainoni - October 22 (1:00 PM - 1:45 PM)
• Waimairi Takeaway Bryndwr - October 23 (4:15 PM - 5:15 PM)
• Kims Corner Dairy Bryndwr - October 23 (4:30 PM - 5:15 PM)
• New World Bishopdale - October 25 (11:30 AM - 12:30 PM)
• Kens Takeaways Bishopdale - October 27 (4:00 PM - 5:00 PM)