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1. Key messages

  • The year 2020 was marked by three major lethal events: the two waves of the COVID-19 epidemic and the August heat wave. These three events resulted in 18.765 deaths in excess.
  • Excess mortality, daily and monthly number of deaths in Belgium were historically high classifying undeniably the first wave of the COVID-19 epidemic as a fatal event.

2. A high excess all-cause mortality was observed in 2020

Be-MOMO estimates 18 765 deaths in excess in 2020. This can be explained by 19 720 COVID-19 deaths in 2020 and excess mortality during the Augustus’ heat wave with 1 545 deaths in excess [1]. However, the number of deaths in excess is less than the total number of COVID-19 deaths. This is because not every COVID-19 death was necessarily an additional death, for the following reasons: (1) some of the COVID-19 victims were of an age at which they were statistically expected to die in the year, and a small proportion of the deaths were probably prevented by lockdown measures, (2) when the number of deaths in excess is calculated over a long period, as is the case over a calendar year, this period includes periods with excess as well as periods of mortality deficits. The excess mortality over a full year is then the result of the sum of these periods of excess mortality and under-mortality, while the number of COVID-19 deaths is always increasing.

Good fit between excess mortality and COVID-19 mortality data from epidemiological surveillance

Based on the data of June 2021, excess mortality was observed in Be-MOMO during the first wave of the COVID-19 epidemic between 20/03/2020 and 28/04/2020. During this period of statistically significant excess mortality, 7 893 deaths in excess were observed (64.3 % of excess mortality) and 7578 persons died of COVID-19 [1,2]. An excess mortality due to influenza can be excluded as the flu epidemic ended on 15 March 2020 and was nonexistent thereafter [2].

During the second wave, there was a statistically significant excess mortality between 20 October 2020 and 24 December 2020, showing 8 350 deaths in excess (41.6% of excess mortality) and 8 686 persons died of COVID-19.

  • First wave
  • Second wave

Number of deaths from all causes from 20 March to 28 April 2020, Belgium
Source: Be-MOMO [2,3], Sciensano


Number of deaths from all causes from 20 October to 24 December 2020, Belgium
Source: Be-MOMO [2,3], Sciensano


During the first wave, an excellent correlation was found between the all-cause mortality and the COVID-19 mortality. This validated the inclusion criteria for the COVID-19-related deaths [4].

Expected number of deaths and confidence intervals, observed number of deaths, and COVID-19 deaths in 2020-2021, Belgium
Source: Be-MOMO [8] and COVID-19 mortality database, Sciensano

The excess all-cause mortality is a more suited indicator than the COVID-19 specific mortality for international comparison of the impact of the COVID-19.

In specific research published in June 2021, Karlinsky and Kobak compared excess mortality in 103 countries. They suggest that the true number of COVID-19 deaths in several countries is greater than the official number of COVID-19 deaths [5].

WHO released a report in May 2022 on estimates of COVID-19 deaths based on excess mortality. They estimate that 14.9 million excess deaths are associated with the COVID-19 pandemic between January 1, 2020, and December 31, 2021 (range from 13.3 million to 16.6 million), compared to official figures of about 5.5 million deaths for the same period. This report highlights not only the impact of the pandemic but also the need for all countries to invest in more resilient health systems capable of maintaining essential health services during crises, including more robust health information systems [6]. For Belgium, the COVID-19 mortality rate for the period 2020-2021 is estimated by the WHO to be an average of 77 per 100,000 inhabitants. Belgium has an intermediate position among the EU-14.

These two studies support that in Belgium the number of COVID-19 deaths reported by the epidemiological surveillance closely matches the excess deaths recorded, indicating correct registration.

Excess deaths associated with COVID-19 pandemic from all causes per 100,000, EU-14, 2020-2021
Source: Global excess deaths associated with COVID-19, WHO [6]

3. Read more


In the context of measuring the impact of the COVID-19 on the mortality, it has been recommended [4-7] to use the excess all-cause mortality to:
  • Measure the global impact of the COVID-19 on the mortality burden
  • Allow international comparisons that are less biased than the COVID-19 mortality
  • Assess the reporting of the COVID-19 mortality resulting from the ad-hoc surveillance system
The number of all-cause deaths in Belgium is registered by the Belgian National Register nearly in real-time (97% of deaths in 2 weeks). However, this information does not contain the cause of death, which will become available after 2 years. The information on all-cause mortality is transmitted to Sciensano via the Be-MOMO project [3]. The weekly updated figures of Be-MOMO can be found on Epistat. 


Be-MOMO project
The Be-MOMO project (Belgian mortality monitoring) is a surveillance of all-cause mortality carried out by Sciensano weekly. The mortality monitoring model is a tool for rapid detection and quantification of unusual mortality (from disease epidemics such as influenza or from extreme environmental conditions such as heat/cold waves or environmental pollution) to guide public health measures, e.g. vaccinations for influenza and the national heat action plan [3,8]. The weekly updated figures of Be-MOMO can be found on Epistat.
Expected number of deaths 
The Be-MOMO model predicts the daily expected number of deaths along with a prediction interval, by modeling the past 5-year mortality data and past epidemic seasons and extreme environmental events (cold and heat waves, and air pollution) [3,8].  
Excess mortality
When the number of observed deaths exceeds the upper prediction limit there is a statistically significant excess mortality for this day [3,8].


  1. Sciensano. Analyse de la surmortalité liée au COVID-19 en 2020. 
  2. Bustos Sierra N, Bossuyt N, Braeye T, Haarhuis F, Peeters I, Proesmans K, et al. Excess mortality during the first and second waves of the COVID-19 epidemic in Belgium (data from 10 March 2020 to 14 February 2021). Brussels: Sciensano; 2021.
  3. Leroy M, Dupont Y, Braeye T, Bossuyt N, Bustos Sierra N. Epistat – Belgian Mortality Monitoring (Be-MOMO).
  4. Bustos Sierra N, Bossuyt N, Braeye T, Leroy M, Moyersoen I, Peeters I, et al. All-cause mortality supports the COVID-19 mortality in Belgium and comparison with major fatal events of the last century. Archives of Public Health. 2020.
  5. Karlinsky A, Kobak D. Tracking excess mortality across countries during the COVID-19 pandemic with the World Mortality Dataset. Davenport MP, Lipsitch M, Lipsitch M, Simonsen L, Mahmud A, editors. eLife. 2021. 
  6. WHO. Global excess deaths associated with COVID-19 (modelled estimates). Available from: 
  7. Institut national d’études démographiques (Ined). The demography of COVID-19 deaths - Seven data-related key issues. Ined - Institut national d’études démographiques.
  8. Cox B, Wuillaume F, Van Oyen H, Maes S. Monitoring of all-cause mortality in Belgium (Be-MOMO): a new and automated system for the early detection and quantification of the mortality impact of public health events. Int J Public Health. 2010. 
  9. Renard F, Scohy A, Van der Heyden J, Peeters I, Dequeker S, Vandael E, et al. Establishing an ad hoc COVID-19 mortality surveillance during the first epidemic wave in Belgium, 1 March to 21 June 2020. Eurosurveillance. 2021. 

Please cite this page as: Sciensano. Factsheets: Excess mortality during the COVID-19 crisis in 2020, Health Status Report, 05 Sep 2022, Brussels, Belgium,