It has long been reported that New Zealanders have high life expectancy. We know the leading causes of health loss, but we do not know how severely COVID-19 will affect the the health of New Zealanders.
A good view of mortality data (note: written about 36 hours ago, as things are changing fast) is available in this Brookings Institute data. https://www.brookings.edu/blog/future-development/2020/03/23/a-mortality-perspective-on-covid-19-time-location-and-age/
Age and underlying health conditions are major factors in the case fatality rate, which also makes the underlying health of New Zealanders a subject of great interest right now.
Below are images from the Health and Independence 2017 report that illustrates causes of health loss and the number of years New Zealanders are living in poor health.