3. Deaths by COVID-19 or related to another cause
The cause of death can be attributed to COVID-19 as a result of various biological tests, clinical diagnosis, or if the infection is mentioned on the death certificate. Patients who died in hospital were usually tested prior to admission.
Deaths at home or in institutions can be qualified in various ways. Therefore, the count of deaths by COVID-19 may differ from country to country depending on the criteria used to attribute the cause of death to COVID-19.
The analysis of death certificates, listing the medical causes that led to death, will make it possible to account for COVID-19 counts. This may be the main cause or may be associated with other diseases. Observations made in hospital show a higher risk of death in cases of multi-morbidity. This result is also consistent with the increased risk of COVID-19 death with age; age also increases the risk of multi-morbidity.
The compilation of statistics on causes of death is a fairly lengthy process; only part of it is quickly accessible, in France or England for example, thanks to the electronic transmission of medical certificates of death; at the time of the French epidemiological review describing the situation on 21 April, just over 5700 electronic death certificates attributed death to COVID-19.
While these partial data can provide an initial insight into the epidemiological profile of the deceased, the analysis of mortality by COVID-19 based on medical death certificates can only be deepened once all the certificates have been processed.
To date, it is possible to use another approach to mortality during the epidemic, using death reports transmitted to national statistical institutes, without identification of the cause.
If deaths directly due to COVID-19 cannot be identified by this source, the excess mortality observed during the epidemic period can be estimated (Pison, Meslé, "The conversation"). In France, the weekly mortality figures published by INSEE very clearly show each year the mortality peaks associated with influenza epidemics. Since the beginning of 2020 and until the first half of March, weekly mortality did not exceed that of the previous year, due to a very low seasonal influenza epidemic in 2020. It was even lower than the mortality in 2018 and 2017, when the influenza epidemic was more lethal.
Since 16 March, mortality has been significantly higher than in previous years. Between 16 March and 6 April, there were more than 76,000 deaths from all causes in 2020, compared to 63,700 in 2019 and 71,000 in 2018 (Insee).
At this stage, it is not possible to determine the share of deaths directly attributable to COVID-19 (main cause), the share of those to which COVID-19 contributed (by weakening the body) and the share of those from other causes, particularly those related to the lockdown situation, in this excess of deaths. While some causes, such as road accidents, have obviously decreased, it is possible that the withdrawal or postponement of consultations or care may have led to deteriorating health status and increased mortality from other causes during this period.
Figure 3.1 Estimated weekly "all-cause" excess mortality in France between 2014 and 2020.