Experts are optimistic the latest rogue case of Covid-19 won't lead to a repeat of Auckland's August outbreak, thanks to the person's small number of close contacts and their vigilance at scanning QR codes.
But two top epidemiologists nonetheless argue it's now time to "turn the tap down" on travel to New Zealand from countries struggling with mass transmission.
The case - a 56-year-old woman released from Auckland's Pullman Hotel on January 13 - visited 30 locations around southern Northland including cafes, restaurants and tourist attractions before developing symptoms and testing positive for Covid-19.
Officials were scrambling to contact trace the woman's movements and notify anyone who may have come into contact with her.
Covid-19 modeller Professor Shaun Hendy said while the new case was concerning, it was not the same situation health officials faced in Auckland in August, when the first cases couldn't be linked to the border.
"With what we know at the moment - that the person has had only four close contacts - it is unlikely that we will need another lockdown," Hendy said.
"Going forward, it will be important to determine whether the person acquired the case in managed isolation and quarantine [MIQ], as this might mean there are other returnees who could have been exposed and officials will want to tighten any procedures that could have led to exposure.
"It is also possible that the person has had a very long incubation period - this is rare, but not unheard of."
Hendy said the genomics of the case would also prove helpful - potentially linking the case to other returnees within MIQ or to cases overseas.
"It will also tell us whether we are looking at one of the new strains. These are becoming
more prevalent overseas so it is certainly a possibility."
ESR and Otago University virologist Dr Jemma Geoghegan said genome sequencing of the case was still ongoing this evening, with no results yet.
It was too early to say whether the person had picked up one of the highly-transmissible variants of the virus.
"Given that we've been sequencing everything that's in MIQ, hopefully we'll be able to link it back to a particular case."
Geoghegan said it was "definitely concerning" there was potential for those variants to be involved, given their higher transmission rate.
"But, given that MIQ procedures in place should be preventing any transmission in the normal sense, I don't think there needs to be any extra precautions taken just because of these variants, because the system should be virus-proof."
She was also encouraged by the person's relatively few close contacts.
"It means that they've probably not been to a super-spreading event, which is something we're always concerned about with Covid-19."
Other experts say the incident should prompt the Government to beef up New Zealand's measures to keep the virus out.
"The Government urgently needs to respond proportionately to the now extremely high risk of an outbreak and uncontrolled spread," Otago University epidemiologist Dr Amanda Kvalsvig said.
"The only proportionate response to that level of risk is to throw everything we have at keeping New Zealanders safe.
"If it looks to many people like an overreaction, then it's probably about right. It would be a terrible tragedy to have more outbreaks and deaths just weeks before the vaccines get to New Zealand."
She said the new variants were much more transmissible - and appeared to cause more severe disease as well.
"In response, the Government must turn down the tap to reduce the number of infectious cases on long-haul flights and in MIQ facilities," she said.
"The Government has a duty of care to protect travellers, MIQ workers, and guests, as well as the general population."
She said a five-day pre-flight hotel quarantine with at least two tests would greatly reduce the risk.
"Reducing the number of MIQ spaces unfortunately looks increasingly necessary until the protective effect of vaccines has properly kicked in."
Her colleague, prominent Otago University epidemiologist Professor Michael Baker, echoed those points.
Around half of travellers currently entering MIQ facilities were coming from "red zone" countries - the US and UK among them - where the virus was running rampant.
"I think that, rather than just accepting anyone who comes in as a fact of life, we need to change that," Baker said.
"It's much more efficient to focus on the 300 people getting on a flight to New Zealand every day than it is the five million people in this country."
But Baker said it was nonetheless crucial Kiwis used the NZ Covid Tracer app everywhere they could.
In the latest case, data expert Dr Andrew Chen said it was heartening to hear the woman had done just that, and was using the Bluetooth tracking function.
But whether others around her, who may have been exposed, were too was another question.
"A person with Covid-19 may not show any symptoms for a few days, but they could be contagious in that time," said Chen, a research fellow with Koi Tū: The Centre for Informed Futures at the University of Auckland.
"We have a case who may have been in the community for 10 days already for example.
"You can't just wait for the outbreak and then start scanning, you need to be scanning as a preventative measure in advance of any cases being detected in the community."