Top epidemiologist Sir David Skegg says anyone crying out for an immediate move to alert level 1 is either ignorant or trying to score political points.
The Otago University professor is warning that a second wave remains a possibility, and complacency is now the greatest threat as Kiwis - buoyed by seven days of no new cases - head into the long weekend with greater freedoms on social gatherings.
"I am glad the Cabinet decided we will remain at alert level 2 for several weeks, " Skegg said in an exclusive interview with the Herald.
"There is abundant evidence from other countries that a favourable situation like ours can very quickly turn to custard."
One of the dangers is that if a Covid-infected person goes to a big gathering, it could trigger dozens of branches of transmission that might take weeks to show up in test results.
That is one of the main reasons director general of health Ashley Bloomfield called for at least 28 days - two two-week incubation cycles - at level 2.
• Covid 19 coronavirus: Expert professor says no blanket quarantine at border risks a longer lockdown
• Watch: Covid 19 coronavirus - Cabinet urged not to play 'Russian roulette' with New Zealanders' health by rushing lockdown decision
• Covid 19 coronavirus: Lockdown 'not enough', top professor tells Govt video conference
• Covid 19 coronavirus: The brink of elimination? Number of higher risk cases down to two
One prominent voice calling for a move to level 1 is Deputy Prime Minister Winston Peters, who this week said the health risks were outweighed by the need to address the economic devastation.
Skegg didn't single out Peters, but made a general comment about the push for level 1.
"People who advocate a move to level 1 straight away are either ignorant or indulging in political posturing."
There is now only one active case in New Zealand. Cabinet is planning to review level 2 settings on June 8 and will meet no later than on June 22 to consider moving to level 1.
Prime Minister Jacinda Ardern has not said what would need to happen to consider moving D-Day to a date earlier than June 22, saying only that Bloomfield's advice will be "fundamental".
Skegg said he understood the desire to move to level 1, especially with the tourism, hospitality and events industries still suffering under level 2 restrictions.
"But if we have to return to higher alert levels, that will be very damaging for the economy and for society.
"Our current control measures are already less restrictive than in most comparable countries, including Australia."
Although great progress had been made, Skegg wanted to see 28 straight days of no new cases before concluding that Covid-19 had been eliminated.
That is in line with the Ministry of Health's elimination strategy.
Skegg has been an independent adviser to Parliament's Epidemic Response Committee, which was formally closed this week.
On the committee, he was a vocal proponent of wider testing, greater contact-tracing capacity and a tighter quarantine at the border before the Government broadened testing criteria, imposed a blanket quarantine, and was trying to rapidly build up contact-tracing.
"There were steps they could have taken more quickly, but it is easy to be wise in hindsight," Skegg said.
"When one compares our situation with that in most other countries, I think we can feel very proud."
Skegg said New Zealand had made "fantastic progress" towards elimination, and its advantages included our marine borders, low population density, and relative lack of crowded public transport.
But he said the country had to confront Covid-19 following decades of chronic underfunding of public health units by successive governments.
In his book last year titled The Health of the People, Skegg wrote: "There must be very few countries in the world, at our stage of development, where the capacity of central government for public health surveillance and action is so weak."
On March 17, the ministry and public health units were able to contact-trace only 10 active cases. At the time, there were already 125 cases - most undetected - in the country.
Countries such as Taiwan have had more success against Covid-19 because of their greater public health resources, despite a less stringent lockdown.
"If our public health capacity - such as for contact-tracing - had not been so run down, we could probably have avoided a lockdown, or at least such a rigorous one," Skegg said.
"Most people would be stunned to hear that our Ministry of Health employed no epidemiologists. A group had to be seconded quickly from the University of Otago [for the Covid response]."
He said there remained questions about contact-tracing that had not been challenged during the weeks of low new cases.
"That situation will change if new cases arise as a result of relaxing border restrictions, such as for Australian visitors or international students."
The ministry is in the process of bringing the 12 regional public health units under a national information system, following Dr Ayesha Verrall's report that highlighted how fragmented and incompatible the system had been.
But the latest data shows that the ministry is still taking nine days to isolate 80 per cent of close contacts after someone's first symptoms.
The benchmark standard for this, according Verrall's audit in April, is four days.
Government report card - generally brilliant
In light of these challenges, Skegg said the Government's performance in general had been "brilliant".
"They acted early and decisively. They have been willing to listen to scientists and to modify policies in response to new evidence."
He said New Zealand had been on the brink of a "terrible situation", which could have overwhelmed hospitals and seen thousands of deaths.
"By late March the number of new cases was rising towards a hundred every day. Early and decisive action was critically important, because of the exponential growth of infections with this virus."
"A group at Columbia University has estimated that the US could have avoided about 54,000 deaths by early May - 83 per cent of the total - if control measures had been introduced only two weeks earlier."
He singled out more heroes beyond government leadership and communication, including: "Sterling work by depleted public health staff (such as medical officers of health and contact tracers), people in the Ministry of Health, and laboratory workers; wonderful support of the lockdown by most people in the community; and a modicum of good luck."
He said there was a danger that the streak of zero-case days would see people with mild symptoms deciding not to get tested.
"This could mean that new cases slip through without being detected."
Borders remained a vulnerable area, and Skegg questioned why air and sea crew were not required to isolate for 14 days.
Air NZ is testing crew at the airport, and Bloomfield has signalled that surveillance testing may be ramped up at the border - but no details have been released.
"There needs to be a thorough review of both surveillance testing and preventive measures at airports and sea ports," Skegg said.
"At present none of us can judge whether or not these are adequate."
He shared other concerns from epidemiologists about the Ministry of Health's presentation of case data.
"All epidemiologists have been frustrated by the unsatisfactory tabulation and updating of information about cases of Covid-19. Often we had to depend on a journalist asking the appropriate question at one of the media conferences.
"I hope there will not be a resurgence of cases but, if that does occur, this problem needs to be addressed."
A transtasman bubble and international students
While Peters has been pushing for some transtasman flights immediately, Ardern has said September is "realistic".
Skegg said Australia was lagging behind New Zealand and he would like to see improvements before flights resumed.
"We will need to see more progress in eliminating Covid-19 in Australia before we could feel comfortable about transtasman travel without quarantine measures," Skegg said.
"Australia is not doing as well as New Zealand in this regard. They are still having a steady stream of new cases each day and they are reporting well over 400 active cases. By contrast, New Zealand now has only one active case."
But Skegg, a former Otago University vice-chancellor, said foreign students returning for the 2021 academic year was more realistic - with managed isolation and testing.
"Complex arrangements and precautions will be required, before and after travel, and I believe it would be unwise to rush this development while we are still working towards elimination."
On Simon Bridges' contributions
Skegg said the Epidemic Response Committee showed the public a side of politics that was less partisan.
"In those early days, everyone was worried about the developing epidemic and wanted to help the country avoid a dangerous situation. It was often difficult to tell which political party a member was representing.
"Simon Bridges was an effective chairman and I'm sure the committee helped to focus the attention of the Government on a number of key issues.
"In several instances, important actions followed quickly."
Without singling out anyone, he said the committee's members became more interested in scoring political points as time marched on.
"I fear this may continue in the reconvened Parliament. Given that this country still faces formidable health and economic challenges, it's a pity that far-reaching decisions have to be made so close to an election."