Underestimation of COVID-19 mortality during the pandemic

Stacey Kung; Marjan Doppen; Melissa Black; Irene Braithwaite; Ciléin Kearns; Mark Weatherall; Richard Beasley; Nethmi Kearns

doi:10.1183/23120541.00766-2020

Underestimation of COVID-19 mortality during the pandemic

ERJ Open Res. 2021 Feb 15;7(1):00766-2020. doi: 10.1183/23120541.00766-2020. eCollection 2021 Jan.

Authors

Stacey Kung¹, Marjan Doppen¹, Melissa Black¹, Irene Braithwaite¹, Ciléin Kearns¹, Mark Weatherall², Richard Beasley^{1

3}, Nethmi Kearns^{1

3}

Affiliations

¹ Medical Research Institute of New Zealand, Wellington, New Zealand.
² Dept of Medicine, University of Otago, Wellington, New Zealand.
³ Capital and Coast District Health Board, Wellington, New Zealand.

Abstract

Background: There has been considerable international variation in mortality during the COVID-19 pandemic. The objective of this study was to investigate the differences between mortality registered as due to COVID-19 and the excess all-cause mortality reported in countries worldwide during the COVID-19 pandemic.

Methods: Ecological analysis of 22 countries compared 5-year historical all-cause mortality, reported all-cause mortality and expected all-cause mortality (calculated as historical mortality plus the reported deaths attributed to COVID-19). Data available from the first week of January 2020 to that most recently available were analysed.

Results: Compared to the preceding 5 years, there was an excess of 716 616 deaths, of which 64.3% were attributed to COVID-19. The proportion of deaths registered as COVID-19-related/excess deaths varied markedly between countries, ranging between 30% and 197% in those countries that had an excess of deaths during the period of observation. In most countries where a definite peak in COVID-19-related deaths occurred, the increase in reported all-cause mortality preceded the increase in COVID-19 reported mortality. During the latter period of observation, a few countries reported fewer all-cause deaths than the historical figures.

Conclusion: The increases in all-cause mortality preceded the increase in COVID-19 mortality in most countries that had definite spikes in COVID-19 mortality. The number of deaths attributed to COVID-19 was underestimated by at least 35%. Together these findings suggest that calculation of excess all-cause mortality is a better predictor of COVID-19 mortality than the reported rates, in those countries experiencing definite increases in mortality.