An international collaboration, led by researchers at the Nuffield Department of Population Health at the University of Oxford, including Professor Martin White of the MRC Epidemiology Unit, has calculated that approximately one million excess deaths occurred in 2020 across 29 high income countries. The results are published today in the BMJ.

Assessing the coronavirus pandemic’s full impact on deaths across the world should include both direct deaths from COVID-19, and indirect deaths from other diseases. This requires estimating the number of ‘excess deaths’: the difference between the number of deaths from all causes during the pandemic and the expected number of deaths (based on historical data from recent years). Calculating excess deaths avoids complications from potential misclassification of deaths from COVID-19, and variations in testing rates between countries.

In this study, the researchers calculated weekly excess deaths in 2020 for 29 high-income countries. Unlike many previous studies on excess deaths during the pandemic, they accounted for age and sex differences between countries, and also for seasonal and yearly trends in mortality over the five preceding years. The results showed that:

• Overall, an estimated 979,000 total excess deaths occurred in 2020 across the 29 countries analysed. All countries experienced excess deaths in 2020, except New Zealand, Norway, and Denmark.
• The five countries with the highest absolute number of excess deaths were the US (approximately 458 000), the UK (94,400), Italy (89 100), Spain (84 100), and Poland (60 100).
• New Zealand was the only country examined which had a lower number of excess deaths than expected (around 2500 fewer deaths). There was little difference between observed and expected deaths for Norway and Denmark.
• The excess death rate increased exponentially with age in both genders. Accounting for differences in age, excess death rates were much higher in men than women. The highest excess death rates (per 100 000) were in Lithuania: for men this was around 360, and for women this was around 152.
• Many countries had major waves of excess deaths during the known peaks of COVID-19 infections (March-May and October- December).
• In most countries, the estimated number of excess deaths exceeded the number of reported deaths from COVID-19: this was 33% higher for the United Kingdom (UK), but over 50% higher for some countries. This suggests that many countries underestimated COVID-19 deaths and/or experienced a significant increase in non-COVID-19 deaths.
• Many countries had lower deaths than expected in children aged less than 15 years. This may be due to fewer injuries (for instance, from car accidents) and/or changes in lifestyle and environmental factors during lockdown (such as reduced air pollution).

Lead Author Dr Nazrul Islam of the Nuffield Department of Population Health said:

Our study adds important insights on the direct and indirect effects of the COVID-19 pandemic on total mortality. It underscores the importance of using age and sex disaggregated data for more nuanced analysis and estimation of the direct and indirect effect of the pandemic.”

Senior author Professor Sarah Lewington, also of the Nuffield Department of Population Health said:

A lack of detailed data from low- and middle-income countries, especially those in Asia and Africa, calls for a globally coordinated effort to improve local capacity in reporting vital statistics to aid evidence-based healthcare policy decisions.”

Dr Ben Lacey, also a senior author at the Nuffield Department of Population Health said:

Reliable and timely monitoring of excess deaths would help to inform public health policy in investigating the sources of excess mortality in populations and would help to detect important social inequalities in the impact of the pandemic to inform more targeted interventions.”

Dr Islam concluded:

Our study provides a detailed and robust assessment of the impact of the covid-19 pandemic on total mortality up to the point that mass vaccination programmes started to become widely available throughout these countries. Future work will be needed to understand the impact of national vaccination programmes on mortality in 2021.”

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• Full paper: Excess deaths associated with covid-19 pandemic in 2020: age and sex disaggregated time series analysis in 29 high income countries Nazrul Islam, Vladimir M Shkolnikov, Rolando J Acosta, Ilya Klimkin, Ichiro Kawachi, Rafael A. Irizarry, Gianfranco Alicandro, Kamlesh Khunti, Tom Yates, Dmitri A. Jdanov, Martin White, Sarah Lewington, Ben Lacey. The BMJ. 19 May 2021. DOI:10.1136/bmj.n1137