Establishing an ad hoc COVID-19 mortality surveillance during the first epidemic wave in Belgium, 1 March to 21 June 2020

Background COVID-19-related mortality in Belgium has drawn attention for two reasons: its high level, and a good completeness in reporting of deaths. An ad hoc surveillance was established to register COVID-19 death numbers in hospitals, long-term care facilities (LTCF) and the community. Belgium adopted broad inclusion criteria for the COVID-19 death notifications, also including possible cases, resulting in a robust correlation between COVID-19 and all-cause mortality. Aim To document and assess the COVID-19 mortality surveillance in Belgium. Methods We described the content and data flows of the registration and we assessed the situation as of 21 June 2020, 103 days after the first death attributable to COVID-19 in Belgium. We calculated the participation rate, the notification delay, the percentage of error detected, and the results of additional investigations. Results The participation rate was 100% for hospitals and 83% for nursing homes. Of all deaths, 85% were recorded within 2 calendar days: 11% within the same day, 41% after 1 day and 33% after 2 days, with a quicker notification in hospitals than in LTCF. Corrections of detected errors reduced the death toll by 5%. Conclusion Belgium implemented a rather complete surveillance of COVID-19 mortality, on account of a rapid investment of the hospitals and LTCF. LTCF could build on past experience of previous surveys and surveillance activities. The adoption of an extended definition of ‘COVID-19-related deaths’ in a context of limited testing capacity has provided timely information about the severity of the epidemic.


Supplementary table 1 -Chronology of the evolution of the COVID-19 case definition Date
Case definition 18/01/2020 Travelers coming back from Wuhan who develop respiratory symptoms during or within 14 days after traveling, should consult their medical doctor and mention the journey.
13/02/2020  Travelers coming back from Wuhan who develop respiratory symptoms during or within 14 days after traveling, should consult their medical doctor and mention the journey.  Persons who had contact with a lab-confirmed case in the 14 days prior to the onset of symptoms should also consult their physician and mention the contact.
18/02/2020 Every person with:  upper/lower respiratory symptoms (acute start of minimal 1 of following symptoms: fever, cough, sore thought, myalgia, respiratory difficulties, headache,…) AND  or a travel history to China in the 14 days before the onset of the disease  or a physical contact with a laboratory confirmed COVID-19 case in the 14 days prior to the onset of the disease. A radiologically confirmed case is a person in whom the laboratory test for COVID-19 is negative, but in whom the diagnosis of COVID-19 is made on the basis of a suggestive clinical presentation AND a compatible CT-scan of the chest.

Confirmed case:
Person with a lab confirmed COVID-19 infection 08/05/2020 Possible case: A possible case of COVID-19 is a person with -at least one of the following main symptoms: cough; dyspnoea; thoracic pain; acute anosmia or dysgeusia without obvious cause; OR -at least two of the following symptoms: fever; muscle pain; fatigue; rhinitis; sore throat; headache; anorexia; watery diarrhea with no apparent cause; acute confusion; sudden fall with no apparent cause ; OR -worsening of chronic respiratory symptoms (COPD, asthma, chronic cough...).

Radiologically confirmed case:
A radiologically confirmed case is a person in whom the laboratory test for COVID-19 is negative, but in whom the diagnosis of COVID-19 is made on the basis of a suggestive clinical presentation AND a compatible chest CT-scan. Supplementary materials to "Establishing an ad hoc COVID-19 mortality surveillance during the first epidemic wave in Belgium, 1 March to 21 June 2020"

Confirmed case:
A confirmed case is defined as a person with laboratory confirmation of COVID-19 infection.

15/05/2020 Possible case:
A possible case of COVID-19 is a person with -at least one of the following main symptoms that appear acute, with no other obvious cause: cough; dyspnoea; thoracic pain; acute anosmia or dysgeusia; OR -at least 2 of the following symptoms, with no other obvious cause, fever; muscle pain; fatigue; rhinitis; sore throat; headache; anorexia; watery diarrhea; acute confusion; sudden fall ; OR -worsening of chronic respiratory symptoms (COPD, asthma, chronic cough...), with no other obvious cause.

Radiologically confirmed case:
A radiologically confirmed case is a person in whom the PCR for COVID-19 is negative, but in whom the diagnosis of COVID-19 is made on the basis of a suggestive clinical presentation AND a compatible chest CT scan.

Confirmed case:
A confirmed case is defined as a person where the diagnosis of COVID-19 infection has been confirmed by a molecular test . Supplementary materials to "Establishing an ad hoc COVID-19 mortality surveillance during the first epidemic wave in Belgium, 1 March to 21 June 2020"