More than a year into the coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the difference in the severity of the clinical syndrome by country-wide income levels has become clear. A new preprint, released on the medRxiv* server, examines some patterns revealed by a study of the factors operating in different regions and countries, to offer plausible hypotheses of these variations.
Several researchers have pointed to factors such as different scales and profiles of social interactions within households, endemic infections and median population age as affecting COVID-19 risk and mortality.
However, these factors have not been found to form a connected framework whereby the risk of clinical severity can be predicted. The current study aimed to set up such a network of hypotheses linked to drivers of viral spread, age distribution among cases and fatalities, and population-level case fatality rates.
The highest number of cases and of deaths due to COVID-19 has been reported in the Americas, while Africa contributes less than 3% of total deaths and an even smaller proportion of global cases, even though it harbors almost 15% of the world’s people.
The reasons offered for the seeming loss of clinical severity in low-income countries (LICs) include those relating to under-ascertainment (less testing, poor access to healthcare), and those relating to more effective or earlier control (proactive containment measures triggered by the warnings issuing from the earlier affected countries, and lower community transmission)…