Review Article

The COVID-19 pandemic in sub-Saharan Africa: The significance of presumed immune sufficiency

Abel O. Idowu, Yusuf O. Omosun, Joseph U. Igietseme, Anthony A. Azenabor
African Journal of Laboratory Medicine | Vol 12, No 1 | a1964 | DOI: https://doi.org/10.4102/ajlm.v12i1.1964 | © 2023 Abel O. Idowu, Yusuf O. Omosun, Joseph U. Igietseme, Anthony A. Azenabor | This work is licensed under CC Attribution 4.0
Submitted: 01 June 2022 | Published: 30 January 2023

About the author(s)

Abel O. Idowu, Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmacy, College of Medicine, University of Lagos, Lagos, Nigeria
Yusuf O. Omosun, Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, Georgia, United States
Joseph U. Igietseme, Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, Atlanta, Georgia, United States; and, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, United States
Anthony A. Azenabor, Department of Pharmaceutical Microbiology and Biotechnology, Faculty of Pharmacy, College of Medicine, University of Lagos, Lagos, Nigeria

Abstract

A novel coronavirus known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in China in 2019 and later ignited a global pandemic. Contrary to expectations, the effect of the pandemic was not as devastating to Africa and its young population compared to the rest of the world. To provide insight into the possible reasons for the presumed immune sufficiency to coronavirus disease 2019 (COVID-19) in Africa, this review critically examines literature published from 2020 onwards on the dynamics of COVID-19 infection and immunity and how other prevalent infectious diseases in Africa might have influenced the outcome of COVID-19. Studies characterising the immune response in patients with COVID-19 show that the correlates of protection in infected individuals are T-cell responses against the SARS-CoV-2 spike protein and neutralising titres of immunoglobin G and immunoglobin A antibodies. In some other studies, substantial pre-existing T-cell reactivity to SARS-CoV-2 was detected in many people from diverse geographical locations without a history of exposure. Certain studies also suggest that innate immune memory, which offers protection against reinfection with the same or another pathogen, might influence the severity of COVID-19. In addition, an initial analysis of epidemiological data showed that COVID‑19 cases were not severe in some countries that implemented universal Bacillus Calmette–Guerin (BCG) vaccination policies, thus supporting the potential of BCG vaccination to boost innate immunity. The high burden of infectious diseases and the extensive vaccination campaigns previously conducted in Africa could have induced specific and non-specific protective immunity to infectious pathogens in Africans.


Keywords

COVID-19; coronavirus; immune response; sub-Saharan Africa; infectious diseases

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