The study is also the first to have assessed the impacts of a country's public health decision-making on the spread of Covid-19 - and reaching a national goal of elimination.
However, it's also highlighted the need to address a problem that was flagged early in New Zealand's Covid-19 experience - systemic barriers around access to healthcare.
The paper unpacked and analysed how New Zealand's science-informed public health measures managed the first wave up to May 13 - a period that saw 1503 cases, 95 hospitalisations and 22 deaths.
Nearly half of those cases - 702 - were linked to just 34 local outbreaks.
Most of New Zealand's cases in that first wave - or 69 per cent - were linked to overseas travel, and tended to be younger adults, Europeans, and with higher socioeconomic statuses.
Still, New Zealand recorded among the lowest numbers of cases and deaths from Covid-19 reported internationally during the first wave, lead author and ESR public health physician Dr Sarah Jefferies said.
Over the crucial 10-day period where New Zealand moved to lockdown, the estimated average daily case infection rate peaked at 8.5 cases per million - and afterward sharply dropped by 62 per cent.
"There was a marked reduction in the spread of disease in the first two weeks of lockdown, and with large improvements in testing capacity, targeting of testing in high risk and vulnerable people, and improving case and contact management, contacts were increasingly traced and cases rapidly detected," Jefferies said.
"Integral to this was the collective efforts of a lot of people, inside and outside the health sector, including every New Zealander who played their role in protecting themselves and their communities."
It further found it was likely its early, intense response, prevented the burden of disease suffered by other high-income countries that were slow to lock down - Australia, the UK and Italy among them.
New Zealand went into lockdown and then had strict rules about gathering limits and mask use on public transport. Photo / Alex Burton
The study stated: "Integral to New Zealand's response has been decisive governance, effective communication, and high population compliance — in an earthquake-prone country, communities and emergency management systems are primed for disaster response."
Jefferies said New Zealand's experience offered valuable insights to other countries.
"We currently face a global challenge where we do not yet have a vaccine against this novel virus and only a few experimental treatments potentially showing promise," she said.
"So, we need to understand how to optimise the use of non-pharmaceutical interventions, such as the measures applied during different alert levels, to inform future responses in New Zealand and around the world."
Early evidence in Asia had suggested that measures like movement restrictions, physical distancing, hygiene, and contact tracing were effective in controlling the pandemic.
But Jefferies said it had been unclear how well this could be implemented in societies with little experience of successfully containing a novel respiratory virus.
"New Zealand followed World Health Organisation advice and combined emerging scientific evidence with leadership and communication strategies.
"Rapid control of community transmission through mandatory physical distancing provided time to enhance the response, including prioritised testing of higher-risk groups to ensure that Covid-19 did not overburden health system capacity."
The study still pointed to one area that needed more focus: tackling health inequity.
"Our study supports the ongoing need for the response to address systemic barriers, such as health-care access, to achieving equitable health outcomes for minority and higher-risk groups, particularly in the absence of elimination."
