Excess mortality during the COVID-19 pandemic: a geospatial and statistical analysis in Aden governorate, Yemen

Abstract

BackgroundThe burden of COVID-19 in low-income and conflict-affected countries remains unclear, largely reflecting low testing rates. In parts of Yemen, reports indicated a peak in hospital admissions and burials during May–June 2020. To estimate excess mortality during the epidemic period, we quantified activity across all identifiable cemeteries within Aden governorate (population approximately 1 million) by analysing very high-resolution satellite imagery and compared estimates to Civil Registry office records.MethodsAfter identifying active cemeteries through remote and ground information, we applied geospatial analysis techniques to manually identify new grave plots and measure changes in burial surface area over a period from July 2016 to September 2020. After imputing missing grave counts using surface area data, we used alternative approaches, including simple interpolation and a generalised additive mixed growth model, to predict both actual and counterfactual (no epidemic) burial rates by cemetery and across the governorate during the most likely period of COVID-19 excess mortality (from 1 April 2020) and thereby compute excess burials. We also analysed death notifications to the Civil Registry office over the same period.ResultsWe collected 78 observations from 11 cemeteries. In all but one, a peak in daily burial rates was evident from April to July 2020. Interpolation and mixed model methods estimated ≈1500 excess burials up to 6 July, and 2120 up to 19 September, corresponding to a peak weekly increase of 230% from the counterfactual. Satellite imagery estimates were generally lower than Civil Registry data, which indicated a peak 1823 deaths in May alone. However, both sources suggested the epidemic had waned by September 2020.DiscussionTo our knowledge, this is the first instance of satellite imagery being used for population mortality estimation. Findings suggest a substantial, under-ascertained impact of COVID-19 in this urban Yemeni governorate and are broadly in line with previous mathematical modelling predictions, though our method cannot distinguish direct from indirect virus deaths. Satellite imagery burial analysis appears a promising novel approach for monitoring epidemics and other crisis impacts, particularly where ground data are difficult to collect.

Excess mortality during the COVID-19 pandemic: a geospatial and statistical analysis in Mogadishu, Somalia

“…(Alawa et al, 2020) Additionally, fear and stigma associated with hospital care and an existing preference for homecare (Tanne et al, 2020) could both have increased the proportion of unreported deaths and burials. As with a similar study in Yemen, results indicate a considerable under ascertainment (Besson et al, 2021) of excess deaths. Given the scarcity of COVID-19 testing in Somalia, such an estimate provides a useful metric for establishing the full impact of the pandemic.…”

Under-reporting of deaths limits our understanding of true burden of covid-19

“…Citizen science initiatives have been relied on in some settings to shed light on the scale of the pandemic. These include drone footage of cemeteries in Aden, Yemen, which provided one of the first indications of under-reporting in the city36 and later prompted the use of satellite imagery to quantify burials 16…”

Signatures of the Venezuelan Humanitarian Crisis in the First Wave of COVID-19: Fuel Shortages and Border Migration

“…Countries in Africa also appeared to have a delayed first wave [ 26 ], with younger age, cross-reactive immunity, previous vaccinations or experience with prior epidemics all invoked as possible causes. However, several studies indicate that insufficient data represent a major explanation [ 27 , 28 , 29 ], with data on excess mortality from funeral houses or burials demonstrating the significant under-ascertainment of deaths. In Venezuela, official data are hard to come by.…”