On measuring COVID-19 excess mortality: Insights and challenges

In this paper, we examine all-cause excess mortality due to the COVID-19 pandemic across 16 countries by age and sex. Utilising the Short-Term Fluctuations data series from the Human Mortality Database, we analyse various measures of excess mortality on weekly and yearly basis from 2020 through the end of 2023. We explore the strengths and limitations of different approaches to offer a comprehensive understanding of the pandemic’s impact on diverse nations. Specifically, we evaluate two methodologies employed by the UK’s Office for National Statistics, considering observed death counts both with and without adjusting for population sizes. We also apply a method based on annual mortality improvements and, as a final approach, implement a statistical model to weekly death counts. Each method defines excess mortality differently, allowing for comparison across alternative perspectives. Our analysis demonstrates largely consistent outcomes across different measures during the first two years of the pandemic, with significant variations in the last two years. These findings contribute to a nuanced understanding of various measures by highlighting their strengths and limitations.