Abstract
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of coronavirus disease 19 (COVID-19), has been rapidly spreading since December 2019, and within a few months, it turned out to be a global pandemic. The disease affects primarily the lungs, but its pathogenesis spreads to other organs as well. However, its mortality rates vary, and in the majority of infected people, there are no serious consequences. Many factors including advanced age, preexisting health conditions, and genetic predispositions are believed to exacerbate outcomes of COVID-19. The virus contains several structural proteins including the spike (S) protein with subunits for binding, fusion, and internalization into host cells following interaction with host cell receptors and proteases (ACE2 and TMPRSS2, respectively) to cause the subsequent pathology. Although the pandemic has spread into all countries, most of Africa is thought of as having relatively less prevalence and mortality. Several hypotheses have been forwarded as reasons for this and include warmer weather conditions, vaccination with BCG (i.e., trained immunity), and previous malaria infection. From genetics or metabolic points of view, it has been proposed that most African populations could be protected to some degree because they lack some genetic susceptibility risk factors or have low-level expression of allelic variants, such as ACE2 and TMPRSS2 that are thought to be involved in increased infection risk or disease severity. The frequency of occurrence of α-1 antitrypsin (an inhibitor of a tissue-degrading protease, thereby protecting target host tissues including the lung) deficiency is also reported to be low in most African populations. More recently, infections in Africa appear to be on the rise. In general, there are few studies on the epidemiology and pathogenesis of the disease in African contexts, and the overall costs and human life losses due to the pandemic in Africa will be determined by all factors and conditions interacting in complex ways.
Highlights
Since late 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of COVID-19, has plagued the world
It is important to know the role(s) of malaria, BCG vaccination, BCG strain type, blood type, age group, genetic background, comorbidities, etc., and their interactions when one is superimposed over the others
It may be too early to speak of low rates of the infection or mortality in Africa because the pandemic is still spreading. e available evidences call for more randomized, controlled studies that take into account all possible variables. e suggested protective effects by BCG, weather, etc. cannot substitute other preventive measures such as face masks, ventilation, and physical distances; all of them are relatively inexpensive and effective when combined. e microbiome may play a role in these complex interactions and needs to be explored
Summary
Since late 2019, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of COVID-19, has plagued the world. SARS-CoV-2 invades larger surface area of the lung It has a high affinity, even higher than that of SARSCoV-1, for its receptor ACE2 [3]. SARS-CoV-1, MERS, and a bat coronavirus use ACE2 as their receptor to enter human host cells [4, 5]. Is leads to shortness of breath, tachypnea, and organ damage These are manifestations of acute respiratory distress syndrome (ARDS). It may cause cardiovascular disease due to inflammatory cytokine surge [6, 7]. COVID-19 causes diffuse pulmonary intravascular coagulopathy in the lungs of COVID-19 patients [6]
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