Public health experts are calling on the Government to "urgently respond" to the case of COVID-19 found in the community in Northland.
A 56-year-old woman, who left Auckland's Pullman Hotel MIQ facility on January 13, later developed symptoms and returned a positive test.
After leaving MIQ, she travelled around southern Northland, including Helensville, Mangawhai, and Dargaville. She has four close contacts, one of which is the person she lives with.
The Ministry of Health said she was "extremely assiduous" in using the COVID Tracer App and scanned into locations as she travelled around.
But Dr Amanda Kvalsvig, a senior research fellow at the University of Otago, Wellington's Department of Public Health, says the Government needs to respond to the "now extremely high risk of an outbreak and uncontrolled spread".
"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," she says.
"It would be a terrible tragedy to have more outbreaks and deaths just weeks before the vaccines get to New Zealand."
Director-General of Health Dr Ashley Bloomfield said during a press conference on Sunday that they are working on the assumption that the woman has a more transmissible strain of COVID-19 - either the United Kingdom or South Africa variant.
In response to these new strains, Dr Kvalsvig says the Government must reduce the number of infectious cases on long-haul flights since it has a duty of care to protect travellers, MIQ workers and guests, and New Zealanders.
"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," she says.
Epidemiologist Professor Michael Baker also believes this could be an additional step that could be taken to help prevent the virus from coming to New Zealand.
"The systematic change here is to reduce the number of infected people arriving on flights from overseas," he told Newshub earlier on Sunday.
"New Zealand could potentially suspend travel from those countries where there's a higher risk of infected people arriving, and also where the new variant is becoming dominant. We could suspend travel for a few months until we have sufficient vaccines in New Zealand to vaccinate all the MIQ workers, and we feel confident that we can manage this risk effectively."
Along with this, a brief period of self-quarantine could be required at an airport in the person's home country along with a rapid test before they board the plane. This would be in addition to the pre-departure test that has been required since earlier this month.
"This is a really big wake-up call for New Zealand, because it reminds us, yet again, that the risk of a border incursion has got a lot bigger," he says.
"That is because most of the countries we receive most of our travellers from going to MIQ are countries where the pandemic is, unfortunately, still out of control."
Psychologist Dr Sarb Johal says investigations of this case are likely to cause concern for many New Zealanders, but that it's worth remembering people tend to have a blind spot for dangers that have a long lead-in time.
He says COVID-19 being present in the community for days before people start testing positive is important to note, and it means it is "absolutely critical" the COVID Tracer app is used to scan into locations.
"The argument that 'we don't need to use the app because we don't have COVID-19 here' is a false one, because the virus may well be present - it just hasn't been detected yet," he says.
"By using the app, you are making a valuable personal and community contribution to being able to tackle any outbreak swiftly, should one occur.
"Use the QR codes, no matter where you are in New Zealand - our response may depend on it."
But Professor Michael Plank of Te Pūnaha Matatini and the University of Canterbury says New Zealand is "well-prepared" for border incursions like this.
"The case has a clear link to the border and has not had a huge number of close contacts in the community. This means there is a relatively low risk that a large number of people have been infected," he says.
"Once we have the results from testing close and casual contacts in the next few days, we will have a clearer picture of whether any change in alert level is needed."
He says whether the woman has a more transmissible strain of the virus will be confirmed by genome sequencing over the coming days, but it is important to still test widely.
"Given that these variants are more transmissible, it makes sense to cast a wide net with contact tracing and testing as many people who may have crossed paths with the case as possible."
COVID-19 Response Minister Chris Hipkins is urging New Zealanders to get tested if they're feeling sick, and then isolate while they're awaiting results.