In one week, Aucklanders can leave the city and travel throughout New Zealand, so long as they're fully vaccinated or can show proof of a negative COVID-19 test in the past 72 hours.
But health experts are warning that once they travel out of the city and people move around the country more freely, more COVID-19 cases will pop up in other parts of New Zealand.
Epidemiologist Professor Michael Baker says the opening of Auckland's boundary on December 15 is "probably the single most consequential COVID-19 response change" before the end of the year.
"Under alert level 3 and 4 restrictions, regional travel was highly limited to prevent infected people spreading the infection more widely. Under the traffic lights system there are no routine travel restrictions, though temporary restrictions can be imposed (as is the case at present for travel into and out of Auckland)," he says.
"Given the relatively high levels of SARS-CoV-2 virus circulating in Auckland, people leaving Auckland in large numbers over the Christmas-New Year period are likely to disseminate the virus widely across New Zealand."
This probably won't result in large outbreaks initially, Baker says, given the country's relatively high vaccination coverage, continued testing, and restrictions on indoor gatherings in hospitality will help limit the spread. But there will "almost certainly" be infections, cases of serious illness, and death, especially when COVID-19 pops up in communities that have low vaccination rates where it can spread more easily.
"The requirement that all people 12 years of age or over are either fully vaccinated or have a negative pre-travel test prior to them leaving Auckland will help to reduce that risk," Baker says.
"However, these requirements for travel within New Zealand are markedly less than the ones that are applied to travellers flying into New Zealand from overseas. Even under the more relaxed requirements that are proposed for international travellers entering New Zealand starting in January next year, all travellers will need a minimum of full vaccination, a pre-departure test, a test on arrival, seven days of self-isolation, and a further test at that point."
But there are ways New Zealanders can reduce the risk of spreading COVID-19 after Auckland's border opens on December 15. Baker says people can encourage others to get tested in addition to being vaccinated, ask Aucklanders to perhaps avoid visiting or staying with unvaccinated or vulnerable family members, and ensure the enforcement of vaccine and testing requirements for those leaving the city.
"Not following these requirements could be seen as comparable to drunk-driving as both of these behaviours have the potential to cause serious harm and death to others. This is not the time to let people off with a warning. The consequences of breaking the law in this situation should include fines and also being required to return to Auckland (until fully vaccinated or tested)," Baker says.
There could be tens of thousands of Aucklanders leaving the city over summer if previous years' data is anything to go off, says Dr Dion O'Neale, the principal investigator at Te Pūnaha Matatini and a lecturer at the University of Auckland's Physics Department.
"It's possible to learn a lot about the number of trips that people make to and from Auckland using data on electronic transactions from past years. During a typical (pre-COVID) week, we would expect to see about 150,000 trips per week into Auckland and about 200,000 trips per week originating in Auckland and travelling outside the region," he says.
"These numbers decreased a bit once COVID reached Aotearoa in 2020, but during periods where the country was at alert level 1, we still saw over 100,000 trips per week to and 200,000 trips from Auckland. This is without accounting for the summer holiday surge in travel when trips outside of Auckland typically double."
O'Neale says removing regional travel boundaries will mean more cases will spread around New Zealand. He adds that while requiring people to be vaccinated or test negative 72 hours before travelling can slightly reduce further cases spreading outside the Auckland region, there are "a number of reasons" why these measures might not be as effective as hoped.
"In the current outbreak, about 24 percent of cases have been in children who are too young to be vaccinated and who aren't required to have a negative test," he says.
"Related to this, although vaccination significantly reduces the chance that you will be infected (and reduces the chance that you will transmit COVID further if you have a breakthrough infection), it does not remove that risk. Similarly, a negative test in the three days before travel is not going to mean that adults are still non-infectious when they travel.
"And while vaccination is great at preventing transmission in general, it can make it trickier to prevent spread outside of a region since it can reduce the symptom severity of breakthrough infections sufficiently that people may not realise that they are infectious when travelling."
Something that could play in New Zealand's favour is the relatively low number of daily cases in Auckland, O'Neale says, but even a period of only 100 daily detected cases means there would be around 1500 active known cases.
"In terms of where Aucklanders typically travel to, Waikato, Northland, and Wellington are the most significant destinations in a typical week," he says.
"With the removal of the travel boundary coming close to the summer holidays, it is possible that Aucklanders' movements might look more like their typical patterns over the Christmas and New Year period where Northland, Thames-Coromandel, and Tauranga-Bay of Plenty see big spikes in incoming trips. The population of Thames-Coromandel, for example, more than doubled over past holiday periods."
O'Neale adds that given many of the regions Aucklanders tend to travel have lower vaccination rates, he hopes that some people choose to stay in the city for the holidays and possibly delay their trip until other areas have caught up their vaccine numbers with major cities.
