The paper develops a Bayesian hierarchical model for expected monthly deaths by age and sex, built on long-term mortality forecasting methods and fitted to 22 years of New Zealand data, including sparse confidentialised counts. Applied from February 2020 to December 2025, it reproduces pre-pandemic features of the series and yields excess-death estimates with wide uncertainty. The estimates show relatively few excess deaths during the pandemic and mortality back on its pre-pandemic trend by 2025.
Why it is interesting: Existing excess-mortality baselines break down after one to two years, which is precisely the window needed to judge whether post-pandemic mortality has returned to trend.