Over- and under-estimation of COVID-19 deaths

Abstract

The ratio of COVID-19-attributable deaths versus "true" COVID-19 deaths depends on the synchronicity of the epidemic wave with population mortality; duration of test positivity, diagnostic time window, and testing practices close to and at death; infection prevalence; the extent of diagnosing without testing documentation; and the ratio of overall (all-cause) population mortality rate and infection fatality rate. A nomogram is offered to assess the potential extent of over- and under-counting in different situations. COVID-19 deaths were apparently under-counted early in the pandemic and continue to be under-counted in several countries, especially in Africa, while over-counting probably currently exists for several other countries, especially those with intensive testing and high sensitization and/or incentives for COVID-19 diagnoses. Death attribution in a syndemic like COVID-19 needs great caution. Finally, excess death estimates are subject to substantial annual variability and include also indirect effects of the pandemic and the effects of measures taken.

Keywords: COVID-19; Death certificates; Diagnostic testing; Excess deaths; Mortality.

Fig. 1

Nomogram of inflation ratio R (test-attributed deaths divided by deaths truly caused by COVID-19) for different combinations of values of X, m, and F. Red color corresponds to r > 5, orange color R = 2–5, yellow color R = 1–2, light blue color R = 0.5–1.0, dark clue color R < 0.5

Fig. 2

Scatterplots of reported COVID-19 deaths as of May 9, 2021 (in deaths per 100,000 population) against (a) overall population mortality rate (annual, per 1000 population) and b percentage of population over 65 years. Panel c shows a scatterplot of the overall mortality rate against the percentage of population over 65 years. Countries with < 50 tests done per 1000 population during the pandemic and those with no information on number of tests done are shown with smaller markers, since under-counting of deaths is very likely in them. Data for overall mortality rate are from ref. 11, data for COVID-19 mortality are from ref. 21 and both data have been completed also from Ref. and from https://www.indexmundi.com/. Data for age structure are from https://data.worldbank.org/indicator/SP.POP.65UP.TO.ZS. All the data are in the Supplementary data file