New Zealand's elimination strategy has made our country the envy of the world so far in the pandemic – and experts say there's little logic in abandoning it now. Science reporter Jamie Morton looks at three obvious reasons for staying the course.
It's protected our health – and our economy
There are now more than enough studies to demonstrate why New Zealand got it right by opting for a zero-Covid strategy that was denied to other countries.
Let's look at a few of them.
One paper, published by Otago University epidemiologists last month, explored data up to the first quarter of this year.
It found that New Zealand had the lowest cumulative Covid-19 death rate in the 38-nation OECD – 26 deaths, or 5.2 per one million of population – which was 242 times lower than the group's average.
In terms of "excess deaths" – or those from all causes during a crisis that were above and beyond those expected under normal circumstances – New Zealand had the largest negative value in the OECD, and equivalent to around 2000 fewer deaths than expected.
Australia - seemingly now looking to choose another path - had the second lowest death rate in the OECD, although it still came in at seven times that of New Zealand's, at 36 per million of population.
The researchers also considered benefits by measuring something called "quality-adjusted life years", or QALYs.
These are generic measures of disease burden, including both the quality and the quantity of life lived.
Based on QALY loss due to premature death from Covid-19, New Zealand's response prevented the equivalent loss of around 38,100 QALYs.
The study acknowledged that New Zealand's tactic came with a large economic hit: largely by closing the country to international tourists, students and workers, and mainly in the first half of last year.
In the second quarter of 2020, for instance, GDP was down more than 10 per cent on the previous quarter, while unemployment levels rose to 5.2 per cent in the third quarter of the year – up 1.1 per cent on pre-pandemic levels.
Yet, the year also saw an economic rebound starting from the third quarter, when GDP was up nearly 14 per cent on the previous one, while the first quarter of 2021 saw positive growth of 1.1 per cent above average.
Going by GDP change over five quarters since the start of the pandemic, New Zealand proved to be the OECD's sixth best performer – at 0.5 per cent vs the OECD average of -0.3 per cent – behind Ireland, Turkey, Chile, Luxembourg and Estonia, and just ahead of Australia.
Those findings echoed a comprehensive Australian study in March, which simulated four different responses in the state of Victoria - which had a similar age, population and income structure to New Zealand - and then analysed how each of them performed against various health and economic indicators.
The four modelled responses included "aggressive" and "moderate" elimination - both which aimed to stamp out the virus altogether, but at different pace.
The former was more akin to New Zealand's "go hard, go early" approach.
The other two strategies - "tight" and "loose" suppression - aimed to minimise spread while living with the virus, and had respective targets of keeping daily cases per million people to between one and five, and five and 25.
While the number of days in hard lockdown were similar across all four strategies, "aggressive" elimination came with the highest percentage of days, with the lowest level of restrictions.
The long-term health impacts of aggressive and moderation elimination were similar, and relatively low, but those for tight and loose suppression were nearly eight and 40 times higher, respectively.
In terms of virus-related deaths over a year-long period, aggressive and moderate elimination kept mortality numbers to 58 and 64 - while the two suppression approaches came with 483 and 2,249 deaths.
The total cost to the economy was estimated to be relatively similar between all strategies, but, from the perspective of health-system related costs, aggressive elimination proved the best option.
For instance, health expenditure costs for the first year came in at $3.7 million for aggressive elimination - compared with $117m for loose suppression.
Otago University epidemiologist Professor Nick Wilson, a co-author of both studies, said commentators arguing against elimination often failed to consider how the strategy had delivered economic benefits to countries that used it.
"If you compare New Zealand and, say, Sweden, which has used a combination of mitigation and suppression, New Zealand has done vastly better on health, and also better in terms of GDP impact," he said.
"So simply, what is their argument? That New Zealand's economy has been wrecked? Our unemployment level is lower than it was before the pandemic."
In another global comparison, the just-released report by an expert group led by Sir David Skegg singled out Scotland: a country with a similar population size to New Zealand.
Compared with New Zealand's 26 deaths, Scotland had suffered more than 10,000 - and a great many more Scots had experienced serious illness.
If New Zealand had held off taking its hardline stance, even for a short while, the window to achieve elimination may have closed - and meant much more death and misery.
Modelling by Te Punaha Matatini researchers, for instance, has indicated that 200 Kiwis may have died had the Government held off ordering the nationwide lockdown for another three weeks - while nearly 12,000 people may have been infected.
New Zealand moved to alert Level 4 on March 25, before dropping back to Level 3 on April 27, during a period when the country registered just over 1500 cases and 22 deaths.
Nearly 11 weeks later, Covid-19 had been eliminated.
Had the shift to Level 4 been delayed by 20 days, the country could have recorded more than 11,500 cases and 200 deaths - and slashed the chance of eliminating the virus to just 7 per cent.
An architect of the strategy, Otago epidemiologist Professor Michael Baker, pointed to a further boon of elimination: the simple fact Kiwis had been able to live relatively normal lives.
"The Economist magazine's Normalcy Index, for instance, puts us right up with Hong Kong in terms of having had the least disruption."
As well, opening up New Zealand's borders wouldn't mean we could suddenly reconnect with the rest of the world - much of which has severe travel restrictions still in place.
Even the UK, increasingly touted as a pathfinder in relaxing Covid-19 rules, required travellers from most European nations to quarantine and be tested before and after travel.
"Elimination has demonstrably been the most successful response," Baker said.
"That's the evidence to date."
We're still vulnerable
As Skegg's advisory group reported to the Government, elimination wasn't only viable, but also the best option at this stage of the pandemic.
Stamping out clusters of Covid-19 as they arose, they found, would mean that New Zealand's health system wasn't overwhelmed by large numbers of patients requiring healthcare.
In some countries, they added, disruptions to healthcare may have caused even more deaths than the virus itself.
Further, our health system remained poorly resourced to deal with any large outbreak.
As New Zealand entered the pandemic, our provision of intensive care beds, per capita, was less than a third of the average among 22 OECD countries.
As the Herald reported on Saturday, the situation hadn't much improved.
There were currently 284 fully staffed ICU beds across public hospitals, and 629 ICU-capable ventilators, with 133 in the national reserve if required.
However, more important than the number of beds or ventilators is whether there are adequately skilled and trained staff to treat the patients using them.
Middlemore Hospital was particularly short-numbered - an alarming weakness given it served more patients with underlying health conditions, who are most vulnerable to Covid-19 infection and serious illness.
Even under Level 4 restrictions, the health system was running at full stretch, meaning there's little ability to absorb more patients without knock-on effects such as delaying surgeries.
Wilson believed that, if not just for saving the system even greater strain, the current elimination strategy needed to stay in place while we completed the vaccination rollout.
As at this week, only a quarter of eligible people had received both doses of the Pfizer/BioNTech shot - and more than half hadn't even received the first dose.
"If we can achieve elimination [after this outbreak], it will allow the vaccination rollout to be achieved before either we abandon some of the control measures, or loosen up border control," Wilson said.
"And even if we decide elimination is not achievable, we'd still want to maintain pretty strict control measures until we get vaccination rates up - that's only sensible."
The strategy can change
It's true that New Zealand's elimination is one of the most - if not the most - hardline Covid-19 strategies in the world.
But that didn't mean it couldn't be modified once we'd completed the vaccination drive.
Prime Minister Jacinda Ardern said as much this week.
"Going through into next year, we'll continue to get the advice of our public health officials and our external advisers and experts as we've always done, and say, 'look, here was our experience through this outbreak. Does it change our approach going forward?", she told reporters on Monday.
"And I expect we will continue to do that over the coming months."
As the Delta outbreak hit, the Government had already been in the process of opening a self-isolation trial for vaccinated travellers to prepare for a "phased resumption" of quarantine-free travel.
Skegg's group found that allowing more quarantine-free travel would raise the risk of Covid-19 entering the country again - and even with high vaccination levels, there'd still be some clusters of infection and occasional large outbreaks.
But, by sticking with elimination, these could be stamped out by public health and social measures such as testing, together with rapid tracing and isolation of contacts, as well as physical distancing and mask-wearing where appropriate.
Scientists remain optimistic the game-plan can still hold even against faster-spreading variants like Delta.
"Obviously an aim would be to minimise the need for raising alert levels, with the economic and social costs these impose," Skegg's group reported.
"Nevertheless, some localised elevations of alert levels may be unavoidable after borders are reopened."
The ongoing need for public health controls was driven home by a just-released modelling study that found re-opening borders without any measures could lead to more than 11,000 hospitalisations - and more than 1000 deaths - within a timeframe of only two years.
And that would be the case even if we managed to vaccinate nine in 10 of all Kiwis - an unlikely probability.
"But high vaccine-induced immunity should certainly make it easier to stamp out outbreaks of Covid-19, using the public health and social measures that have been so important over the last year," Skegg's group pointed out.
Baker turned to the UK's current situation.
"The UK has high vaccination rollout rate, and quite high immunity when you consider exposure to the virus as well," he said.
"But at the same time, it has a lot of virus circulation - more than 30,000 cases, and getting up towards 1000 hospitalisations and 100 deaths - a day.
"If that's the best you can hope for, that's still pretty grim. That's basically clogging up your whole health system.
"Translated to New Zealand, we could be looking at 2500, maybe 3000 deaths each year - or five times more than influenza - and that would add about 10 per cent to our annual mortality risk rate.
"So, I say that, if that's the scenario we're heading towards, is that really what people want?"
For the time being, it appeared the answer was no.
A new Spinoff-commissioned poll has suggested seven in 10 Kiwis favour sticking with elimination - with just 10 per cent opposed.