In December 2019, a cluster of patients with pneumonia of unknown aetiology was linked to an infection with a novel coronavirus - the SARS-CoV-2. Since then, the infection has become pandemic and spread affecting almost every country in the world. Knowledge of virus dynamics and the host's immune response to it is essential to understanding the pathogenesis as well as in formulating diagnostic, therapeutic and preventive strategies. There are no studies, however, related to these issues, particularly in Sub-Saharan Africa (SSA) context. Previous studies by the investigators have shown that the immune profile of healthy Ethiopians shows evidence of chronic immune activation with significant low nave cells but high activated memory cells, of both CD4+ and CD8+ T-cell sub populations. The above immune system characteristics of Ethiopians as compared to Europeans led the investigators to the assumption that these could contribute to possibly milder COVID-19 symptoms, lower viral loads and thus reduced transmissibility. Persistent immune activation due to continuous infections with protozoa and helminths is common in the entire SSA region. Such activation usually skewes the immune system towards T helper (Th)-2-type responses. The immune response against SARS-CoV-2 is typically of a Th1 type. Here, the investigators hypothesize that SARS-19 induced immune activation as observed in patients in the industrialized world (with concomitant cytokine storms and extensive non-specific CD8 T-cell cytotoxicity) is more prominent than in people from SSA, due to the Th2 profile of their immune system.

The investigators propose to study the profile of the immune response of Ethiopian population and will examine its relationship with the noted low CD4+ T-cell count and underlying immune activation status among patients with COVID-19 and will compare results with those residing in Europe. Current diagnosis of SARS-CoV-2 infection is based on molecular assays, their availability in SSA is limited. Hence, this project will evaluate the performance of various rapid diagnostic tests (RDTs) for SARS-CoV-2, taking into account the above-determined immune system characteristics. In addition, the investigators will evaluate the RDTs for use in the screening of infected patients who are asymptomatic, in particular in health-care settings, as well as for monitoring recovery or clearance of virus shedding for use in resource-constrained setting. Such comparative studies will help identify immune factors that could play a role in attenuating the disrupted immune responses caused by SARS-CoV-2 infection and thus contribute to the design and development of effective diagnostic, therapeutic or vaccine.