Excess deaths in New Zealand

Is it really bucking the trend?

The official data shows minimal excess mortality in New Zealand which can all be accounted for by deaths attributed to covid.

Figure 1: Official cumulative excess and covid deaths

The big question is why deaths were so low in 2020 and 2021. Notably, if deaths attributed to covid are subtracted the mortality remains very low currently. It has been argued that missing influenza deaths may have contributed to the decrease and that is possible. It does bring into question the accuracy of the baseline. Were people wrongly expecting more deaths than it is reasonable to expect?

It all depends where you estimate the trendline from. Figure 2 shows age standardised mortality. By taking the mortality rate for each age group and projecting it onto a population with a set number of people in each age group, fairer comparisons can be made. I have presented it as data from June to July which splits the winter months but allows for a clear distinction between pre-vaccine and post-vaccine periods.

Figure 2: ASMR from June to July for New Zealand with two alternative trendlines

The orange trendline is based on the data from June 2011 to July 2016 and projecting that forward. It would suggest there were bad years for mortality in 2017 and 2018, when there was indeed a high influenza mortality, but that 2020/2021 the expected number of deaths.

The green trendline is based on data from June 2015 to July 2020. The extent of the excess since 2020 is markedly different depending which of these measures is used.

The key point is that no-one knows. It is impossible to say how many deaths there should have been. Should ASMR keep declining? Should it plateau? Might it rise? Who knows! Any estimates of excess are by definition subjective and based on assumptions that are not always reasonable ones. Anyone sticking to the official measures needs to explain why the non-covid deaths are so much lower than predicted.