New Zealand’s pandemic response has been globally lauded for saving thousands of lives – and now, a major analysis suggests much of its wider health benefits have been sustained over the long-term.

While Covid-19 has claimed around 3,250 Kiwi lives since 2020, while causing myriad other impacts and disruptions, successive studies have validated the hardline approach New Zealand initially took with all-out elimination.

Otago University researchers have estimated that, had the country not largely succeeded at keeping the virus at bay for the pandemic’s first two years, thousands of Kiwis would have died.

They calculated a US or UK experience would have translated, per capita, to 19,900 and 13,700 more deaths here respectively over that period.

Now, Medical Research Institute of New Zealand (MRINZ) have again put mortality rates under the lens, to answer whether our elimination strategy had resulted in a much-speculated “rebound” of deaths from all causes.

Their findings, published in prestigious scientific journal The Lancet, suggest there’s been no such major effect since December 2021, when the arrival of Delta and our vaccination roll-out brought an end to elimination.

Using Stats NZ data, the researchers found that stamping out Covid-19 brought about an 11 per cent reduction in “all-cause” mortality over a 30-week period in 2020, contrasting dramatically with other countries over-run by the virus at that time.

In that first year, New Zealand recorded around 440 fewer deaths per million – something that also owed to the temporary squashing of flu transmission, and a drop in deaths from road and work accidents, air pollution and post-surgical complications.

The next year, weekly mortality rates fluctuated around the historical average.

With the arrival of Omicron, New Zealand’s excess mortality - or that above and beyond the “normal” rate in the decade before the pandemic - then rose to about 660 deaths per million of population in 2022, largely due to Covid-19.

Over those three years however, the analysis showed that loss of life from causes other than Covid-19 had been reduced.

Virus-attributed mortality aside, there were some 11.7 fewer deaths per million of population in 2021, and just around 209 more deaths per million in 2023, compared with historical rates.

“New Zealand has been a country of considerable global interest in view of its elimination strategy for Covid-19, which prevented the high rates of mortality from Covid-19 experienced by most other countries,” MRINZ director and study author Professor Richard Beasley said.

“What this study has shown is that the benefits have been maintained long term, even after relaxation of most of the public health measures.”

Fellow author, and MRINZ’s Covid-19 programme lead, Dr Thomas Hills, said the patterns were “informative” for guiding public health measures for future pandemics.

It follows an earlier analysis showing how New Zealand was the only one of four territories that managed to shift from a zero-Covid policy while keeping “excess deaths” low.

In that paper, Hong Kong researchers compared rates of excess mortality in New Zealand, Australia, South Korea and Singapore as each shifted to living with the virus.

While Singapore, South Korea and Australia had rises in excess mortality of 20 to 40 per cent after the transition, New Zealand’s rate stayed within 10 per cent – something the study authors partly attributed to an “ultra-high” vaccination rate among older people.

The results come as another major study has reviewed international scientific evidence on the effectiveness of “non-pharmaceutical interventions” used in the pandemic, ranging from lockdowns and border restrictions, to masking, social distancing and contact tracing.

Using New Zealand as a key case study, its UK authors found these measures granted limited protection on their own, but when combined, were “unequivocally effective in reducing the spread of infections” while vaccines and anti-virals were being developed.

Otago University epidemiologist Professor Michael Baker, a key architect of our elimination strategy, said the new research was helpful.

“Aotearoa New Zealand’s experience has shown that these measures can protect an entire nation for more than a year while pharmaceutical measures are being developed.”