A recent published medical study is shining the light on the speculation about the possible long-term effects of New Zealand’s Covid-19 elimination strategy on mortality rates  and, in particular, whether it might have led to a rebound increase in loss of life from other causes.

This speculation has been put under a scientific lens by the Medical Research Institute of New Zealand (MRINZ), through an analysis of weekly all-cause New Zealand mortality rates using data from Stats NZ Tatauranga Aotearoa.

A study, published by the MRINZ in the prestigious international medical journal The Lancet, shows that while there has been a significant burden of Covid-19 deaths there has not been a substantive rebound in deaths from non-Covid causes since December 2021, when New Zealand moved from an elimination strategy to a mitigation strategy after achieving high vaccination rates.

“The patterns of mortality observed in the study are informative in terms of guiding public health measures for future pandemics,” says MRINZ Covid-19 programme lead and study author Dr Thomas Hills.

The report showed that in 2020, the elimination strategy not only successfully eradicated Covid-19, but also resulted in an 11 per cent reduction in all-cause mortality over a 30-week period, an outcome that contrasted markedly with most other countries globally in which all-cause mortality increased due to the pandemic.

In fact, there were around 440 fewer deaths per million in New Zealand in 2020, likely due to numerous potential factors including the elimination of Covid-19, markedly reduced burden of influenza and other respiratory viruses, and fewer deaths from road traffic accidents, occupational causes, air pollution and post-surgical complications.

In 2021, weekly mortality rates fluctuated around the historical average.

In 2022 when widespread community transmission of the Omicron variant occurred, the New Zealand population was highly vaccinated, and public health restrictions were progressively relaxed. During this time there was excess mortality of about 660 deaths per million population, predominantly due to Covid-19.

As a result, total mortality rate minus Covid-19-attributable deaths was 444·5 fewer deaths per million population in 2020, 11·7 fewer deaths per million population in 2021, and 209·3 more deaths per million population 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,” says MRINZ director and study author Professor Richard Beasley.

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

Key points at a glance:

‘New Zealand’s COVID-19 elimination strategy and mortality patterns’ study, authored by Stacey Kung, Thomas Hills, Nethmi Kearns, and Richard Beasley, was published in the Lancet on Thursday August 24.

The study compared weekly all-cause mortality rates in New Zealand in 2020, 2021, and 2022, with historical figures from 2011 to 2019.

Overall, during the three years of the pandemic, loss of life due to causes other than Covid-19 was reduced.

The report shows there has not been a substantive rebound in deaths from non-Covid causes since December 2021, when New Zealand moved from an elimination strategy to a mitigation strategy after achieving high vaccination rates.

All-cause mortality in New Zealand was reduced in 2020 and 2021 due to the Covid-19 public health measures.

Link: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)01368-5/fulltext

Medical Research Institute of New Zealand 
Rangahautia Te Ora

The Medical Research Institute of New Zealand (MRINZ) is New Zealand’s leading independent medical research institute. MRINZ research is guided by a simple philosophy: it must challenge dogma, increase knowledge, and have the potential to improve clinical practice and outcomes, both in Aotearoa New Zealand, and internationally. Committed to contributing toward a more equitable society that celebrates Te Ao Māori and upholds Te Tiriti o Waitangi, MRINZ’s research teams are dedicated to investigating important public health problems, delivering high quality evidence on which to improve the management of disease and patient care. 

Tom Hills, MRINZ Covid-19 programme lead 
Tom Hills’ mahi sits at the intersection between clinical practice and clinical research. Alongside his role at MRINZ, Tom works in Auckland as a Clinical Immunology and Infectious Diseases Physician. Collaborating with researchers locally and internationally, Tom’s work has culminated in several high-impact publications including in the New England Journal of Medicine, The Lancet, and the Journal of the American Medical Association. 

Professor Richard Beasley, MRINZ Director 
Richard Beasley, MBChB, MD, DSc, CNZM, is a physician at Wellington Regional Hospital, Director of the Medical Research Institute of New Zealand, Professor of Medicine at Victoria University of Wellington, and Visiting Professor, University of Southampton, United Kingdom. He was previously the Deputy Chair of the Health Research Council of New Zealand. His research interests in respiratory medicine are primarily in the fields of epidemiology and clinical management.