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

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 SARSCoV-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 Calmette­Guerin (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.

Children caught in the long shadow of COVID-19

Despite the more transmissible delta variant being associated with higher rates of COVID-19 in unvaccinated adolescents, children have remained relatively spared from severe disease. Nevertheless, children are indirectly affected by the COVID-19 pandemic, which threatens to have far-reaching consequences. The effect of disruptions of seasonal patterns of circulation of respiratory pathogens on future immunity against such pathogens, childhood immunization programmes, and HIV and tuberculosis treatment programmes poses a threat to the future wellbeing of children. Furthermore, the economic devastation caused by the pandemic, including an increase in unemployment, gives rise to numerous challenges, such as food insecurity, which is likely to worsen childhood nutritional status. Also, COVID-19 has ongoing effects on the mental wellbeing of children, driven in part by the interruption of schooling and other opportunities to socialize. An increase in psychological illnesses has manifested in children consequent to the stresses of the pandemic, lockdowns, caregiver deaths. In this article, we highlight the indirect effects of COVID-19 on children, and suggest solutions to mitigate against the long-term sequelae. A focused health, nutrition, education and child protection response is required from government and healthcare practitioners to safeguard the health and wellbeing of South African children.

Complex interactions between malnutrition; infection and immunity: relevance to HIV/AIDS infection

Various grades of protein-energy malnutrition; usually complicated by concurrent micronutrient deficiencies; occur extensively in Nigerian populations who are consequently; immunologically compromised. The affected individuals present with marked tissue depletion of the antioxidant nutrients; including glutathione ((-glutamyl-cysteinyl-glycine) and its enzymes. HIV infection in deprived subjects intensifies the nutritional deficits and further enhances cellular oxidative stress. The latter; by modifying the functions of such transcription factors as NF-9B; contributes to HIV replication and acceleration of disease progression. In the HIV-infected individual who is usually anorexic; the marshalling of nutrient resources from endogenous sources to promote optimal immune function is of high importance; but this is compromised in the malnourished. The importance of good nutrition in HIV management in Nigeria is not diminished by the advent of antiretroviral drugs; whose metabolic effects on underprivileged; malnourished subjects are yet to be carefully characterized

Complex interactions between malnutrition; infection and immunity: relevance to HIV/AIDS infection

Various grades of protein-energy malnutrition; usually complicated by concurrent micronutrient deficiencies; occur extensively in Nigerian populations who are consequently; immunologically compromised. The affected individuals present with marked tissue depletion of the antioxidant nutrients; including glutathione ((-glutamyl-cysteinyl-glycine) and its enzymes. HIV infection in deprived subjects intensifies the nutritional deficits and further enhances cellular oxidative stress. The latter; by modifying the functions of such transcription factors as NF-9B; contributes to HIV replication and acceleration of disease progression. In the HIV-infected individual who is usually anorexic; the marshalling of nutrient resources from endogenous sources to promote optimal immune function is of high importance; but this is compromised in the malnourished. The importance of good nutrition in HIV management in Nigeria is not diminished by the advent of antiretroviral drugs; whose metabolic effects on underprivileged; malnourished subjects are yet to be carefully characterized

Immune activation; allergic drug toxicity and mortality in HIV-positive tuberculosis

This study was conducted to correlate serum levels of markers of immune activation with mortality and drug toxicity in HIV+TB. Design: Substudy of a randomised clinical trial of streptomycin-thiacetazone-isoniazid (STH) vs. rifampin-isiniazid-pyrazinamide (RHZ) in HIV + TB. Design: Substudy of a randomized clinical trial of streptomycin-thiacetazone-isoniazid (STH) vs. rifampin-isoniazid-pyrazinamide (RHZ) in HIV + TB. Results: Neopterinor =14 ng/mg; TNF-alpha receptorsor = 6.5 ng/ml; and negative skin test were independently associated with increased mortality (P0.01). Among STH-treated subjects; dermatologic toxicity and mortality (P0.05); although these two adverse events occurred independently. Activation markers increased from baseline after 2 months of therapy with the less rapidly bactericidal STH regimen; whereas they declined in those treated with RHZ; suggesting a relationship with continued mycobacterial replication. Conclusions: Immune activation in HIV+TB is associated with shortened survival and increased risk of drug toxicity. HIV+TB patients with elevated serum neopterin should be treated with a rapidly-bactericidal drug regimen which does not include thiacetazone

Improved survival rate in neonatal tetanus among babies of immunised mothers

Fifty-two neonates admitted for tetanus into our neonatal unit at Wesley Guild Hospital; Ilesa over a thirty-month period were analysed in relation to maternal immunisation with tetanus toxoid during pregnancy. Seventeen (32.7) of the babies were delivered to mothers who had tetanus toxoid immunisation during pregnancy. The male to female ratio; mean age and weight of babies in the two groups were similar. Six mothers took discharge of their babies against medical advice. Twenty (43.5) of the remaining 46 babies died. The fatality rates in the 16 infants of mothers who had tetanus toxoid and 30 infants of mothers who did not have tetanus toxoid during pregnancy were 12.5and 60respectively (P0.01). This report thus shows that neonatal tetanus can occur in babies of mothers immunised with tetanus toxoid during pregnancy but that maternal immunity probably improved the prognosis of neonatal tetanus in such infants