Experts have questioned the new report, with one calling its border proposal "impractical".
Published today but written in August 2020, the report is based on the Covid-19 situation at that time. Since then, new Covid-19 strains have spread around the world, including in New Zealand where the South African variant infected the recent community cases.
The University of Auckland's Professor Shaun Hendy said its specific conclusions have been "overtaken by global events".
But the authors say despite the document being based historic figures, "they don't change the overall conclusion, which is built on a dynamic model that changes daily to reflect the exact figures".
The report puts the case forward for a "traffic light" or risk-based border control system where international travellers are rated according to the Covid-19 situation in their origin country.
Under the system, travel would be unrestricted from Covid-19-free locations, as of August 2020, like Taiwan and Thailand.
"With regular surveillance, no imported infections are expected," the report said.
Travellers coming from countries classed as either level 1, 2 or 3 would have a PCR test before being allowed on the plane and then face different durations of MIQ in New Zealand.
The Government has introduced universal pre-departure testing since the report was written.
Level 1 travellers would be tested on arrival in New Zealand and spend one night in MIQ and level 2 travellers would stay five nights in MIQ and have a test on day four.
Level 3 and 4 travellers would stay the full 14 days in quarantine and be tested on day three and 12.
Auckland Airport chief executive Adrian Littlewood said the model was dynamic in that the recommended controls would change as a country's risk profile changes.
"In the case of Australia, a state-by-state risk-rating can also be assessed should state-to-country re-opening become possible."
The report predicts more than 60,000 travellers a month would come into the country under the model, up from the 11,271 who entered in August 2020.
That would be a relief for tourism operators struggling to keep their heads above the water with no international tourists.
Across all travellers and levels, the report said as of August 2020, 24 infections per month would enter the "traveller journey", that around half would be screened out in the pre-departure test and, following MIQ, 0.50 (one infection every two months) will exit MIQ undetected.
It also said that as travellers would have different quarantine times, MIQ could process them faster.
Littlewood said the model was in line with emerging international standards that encourage each country to design strong border controls that match each country's virus management strategy.
"As a business that normally welcomes more than 70 per cent of passengers into our country, we need to be planning long-term for a future where our staff and terminal infrastructure are responding to new requirements and protections to reduce the risk of virus transmission. Gaining a science-based understanding of the border risks and mitigations is key to this future planning."
Experts react
Professor Hendy said while the study is useful, it doesn't provide a "workable scheme" for managing travel bubbles.
The report uses fatalities as a matter of calculating traveller risk, which Hendy said was "questionable" as there was a three-week lag period between infection and death.
"Looking back to March 2020, if we had been using the system proposed by the authors, the lag between infection and death would probably have prevented us from escalating border controls fast enough to prevent the alert level 4 lockdown."
The University of Canterbury's Professor Michael Plank said the model's predicted risk means that breaches like the one that occurred at the Pullman Hotel recently will occur 20-50 per cent more frequently.
Plank said there are also several other factors any border relaxation plan would need to consider, including risk to border workers.
"The majority of our border breaches have occurred when a border worker got infected by a recent arrival. If the number of infected arrivals increases, this will also increase the risk of future infections in border workers."
He said a risk-based border system based on current Covid-19 rates in different countries "makes sense" and would be needed to relax border restrictions once the world begins to emerge from the pandemic.
But, for now: "Covid-19 is more prevalent now than at almost any point in the past. At the moment, we need to do everything we can to reduce the risk of importing Covid-19 into the community, not taking on additional risk."
The University of Auckland's Dr David Welch said many people have called for the number of travellers entering New Zealand from different countries to be based on the Covid risk in those countries.
"But they estimate, based on August 2020 figures which have since dramatically changed, that this would result in roughly 25 per cent more cases in the community than we have so far had. The model could equally be used to argue that the numbers from high-risk countries be reduced to lower overall risk."
