Why is There Low Morbidity and Mortality of COVID-19 in Africa?

Njenga, M. Kariuki; Dawa, Jeanette; Nanyingi, Mark; Gachohi, John; Ngere, Isaac; Letko, Michael; Otieno, CF; Gunn, Bronwyn M.; Osoro, Eric

doi:10.4269/ajtmh.20-0474

Cited by 167 publications

(187 citation statements)

References 39 publications

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“…There is however a good reason to believe that Africa did not experience the same severity of disease found in the other continents. 22 Objectively, the seroprevalence of COVID-19 among asymptomatic healthcare workers in this study was 45%, indicating a latent exposure to the disease, and this is even higher than seroprevalence in the general population in France, Italy, and Spain where mortality was massive. 23 This high prevalence is not surprising because the hospitals were opened for most of the pandemic period, and healthcare workers continued to attend patients with minimal precautionary measures.…”

Section: Discussionmentioning

confidence: 53%

SARS-CoV-2 Seropositivity in Asymptomatic Frontline Health Workers in Ibadan, Nigeria

Olayanju

Bamidele

Edem

et al. 2021

The American Journal of Tropical Medicine and Hygiene

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Global health has been thrown into turmoil by the COVID-19 pandemic, which has caused devastating morbidity and unprecedented loss of life in almost all continents of the world. It was predicted that the magnitude of the pandemic in Africa will be high because of poor health structure and intensely poor living condition, but that has not happened, surprisingly. It was hypothesized that the youthful population and a vastly primed immune system were protective, and many people may have been exposed without coming down with the severe disease. Most of them would have presented in hospitals with other medical conditions and possibly transmit COVID-19 to health workers inadvertently. This study is designed to measure serum SARS-CoV-2 IgG levels in health workers as a marker of latent exposure. Asymptomatic frontline health workers were randomly selected from the University College Hospital Ibadan, Nigeria; venous blood samples were obtained from them, and the serum SARS-CoV-2 IgG level was determined using ELISA techniques. A proportion of participants with seropositivity were obtained, and factors associated with seropositivity were determined. A total of 133 participants were recruited for this study, and 60 (45.1%) of them were seropositive for SARS-CoV-2. Among the seropositive participants were doctors, nurses, health assistants, laboratory scientists and technicians, and nonmedical staff. Obstetrics, gynecology, and emergency departments had higher odds of seropositivity. Seroprevalence of SARS-CoV-2 is very high among frontline health workers, though asymptomatic. This calls for a more stringent precaution against further spread within the hospital environment.

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Section: Discussionmentioning

confidence: 53%

SARS-CoV-2 Seropositivity in Asymptomatic Frontline Health Workers in Ibadan, Nigeria

Olayanju

Bamidele

Edem

et al. 2021

The American Journal of Tropical Medicine and Hygiene

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“…On the other hand, the above results does not falsify the hypothesis that CoVID-19 interacts negatively with other pathogens. The prevalence of toxoplasmosis may act as a proxy measure of group hygiene and our results may indicate a negative interaction of CoVID-19 with other, yet unidentified pathogens that are more widespread in resource-poor countries 16 . www.nature.com/scientificreports/ Coronaviruses surround us, and we most probably get into unnoticed and symptomless contacts with human coronaviruses like HCoV-OC43 and HCoV-229E, and porcine and feline coronaviruses (PEDV, FCoV) quite frequently.…”

Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 78%

A negative covariation between toxoplasmosis and CoVID-19 with alternative interpretations

Jankowiak

Rózsa

Tryjanowski

et al. 2020

Sci Rep

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Coronaviruses may exert severely negative effects on the mortality and morbidity of birds and mammals including humans and domestic animals. Most recently CoVID-19 has killed about half million people (27th of June, 2020). Susceptibility to this disease appears to differ markedly across different societies but the factors underlying this variability are not known. Given that prevalence of toxoplasmosis in human societies may serve as a proxy for hygiene, and it also exerts both direct and immune-mediated antiviral effects, we hypothesize a negative covariation between toxoplasmosis and measures of the CoVID-19 pandemic across countries. We obtained aged-adjusted toxoplasmosis prevalence of pregnant women from the literature. Since the differences in the CoVID-19 morbidity and mortality may depend on the different timing of the epidemics in each country, we applied the date of first documented CoVID-19 in each country as a proxy of susceptibility, with a statistical control for population size effects. Using these two indices, we show a highly significant negative co-variation between the two pandemics across 86 countries. Then, considering that the wealth of nations often co-varies with the prevalence of diseases, we introduced GDP per capita into our model. The prevalence of toxoplasmosis co-varies negatively, while the date of first CoVID-19 co-varies positively with GDP per capita across countries. Further, to control for the strong spatial autocorrelation among countries, we carried out a Spatial Structure Analyses of the relationships between the date of first CoVID-19, prevalence of toxoplasmosis, and GDP per capita. Results of this analysis did not confirm a direct causal relationship between toxoplasmosis and susceptibility to the CoVID-19 pandemics. As far as an analysis of observational data let us to suggest, it appears that the interaction between CoVID-19 and toxoplasmosis is mediated by GDP per capita and spatial effects. This prompts the question whether the formerly known covariations of CoVID-19 and BCG vaccination or air pollution might have also emerged as spurious indirect effects. Coronaviruses are positive-stranded RNA viruses that may exert severely negative effects on the mortality and morbidity of a broad range of birds and mammals including humans and domestic animals. The strain called SARS-CoV-2 host-switched from bats to humans in Wuhan, China in November 2019 and subsequently gave rise to a devastating global pandemic called CoVID-19 1-3. Susceptibility of human societies appear to be markedly heterogeneous ranging from modest to very high morbidity. Contrary to general expectations, more developed, wealthier communities living under better hygienic conditions appear to be more threatened than others. Thus, Austria is seemingly more severely hit than Hungary, the Czech Republic than Slovakia, and Israel than Palestine or Jordan.

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“…However, the reasons behind the discrepancy in the COVID-19 pandemic trajectory between SSA and elsewhere might include population demography, climate and prior cross-reactive immunity ( 16 ). In Malawi, for example, the population is younger (median age 17 years old) ( 11 ), and the elderly who mostly experience worse outcomes in other settings ( 10 ), are 5.1% of the population ( 11 ), largely residing in rural areas.…”

Section: Resultsmentioning

confidence: 99%

High SARS-CoV-2 seroprevalence in Health Care Workers but relatively low numbers of deaths in urban Malawi

Chibwana

Jere

Kamng’ona

et al. 2020

Preprint

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Background In low-income countries, like Malawi, important public health measures including social distancing or a lockdown, have been challenging to implement owing to socioeconomic constraints, leading to predictions that the COVID-19 pandemic would progress rapidly. However, due to limited capacity to test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, there are no reliable estimates of the true burden of infection and death. We, therefore, conducted a SARS-CoV-2 serosurvey amongst health care workers (HCW) in Blantyre city to estimate the cumulative incidence of SARS-CoV-2 infection in urban Malawi. Methods Five hundred otherwise asymptomatic HCWs were recruited from Blantyre City (Malawi) from 22nd May 2020 to 19th June 2020 and serum samples were collected all participants. A commercial ELISA was used to measure SARS-CoV-2 IgG antibodies in serum. We run local negative samples (2018 - 2019) to verify the specificity of the assay. To estimate the seroprevalence of SARS CoV-2 antibodies, we adjusted the proportion of positive results based on local specificity of the assay. Results Eighty-four participants tested positive for SARS-CoV-2 antibodies. The HCW with a positive SARS-CoV-2 antibody result came from different parts of the city. The adjusted seroprevalence of SARS-CoV-2 antibodies was 12.3% [CI 9.0-15.7]. Using age-stratified infection fatality estimates reported from elsewhere, we found that at the observed adjusted seroprevalence, the number of predicted deaths was 8 times the number of reported deaths. Conclusion The high seroprevalence of SARS-CoV-2 antibodies among HCW and the discrepancy in the predicted versus reported deaths, suggests that there was early exposure but slow progression of COVID-19 epidemic in urban Malawi. This highlights the urgent need for development of locally parameterised mathematical models to more accurately predict the trajectory of the epidemic in sub-Saharan Africa for better evidence-based policy decisions and public health response planning.

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Why is There Low Morbidity and Mortality of COVID-19 in Africa?

Cited by 167 publications

References 39 publications

SARS-CoV-2 Seropositivity in Asymptomatic Frontline Health Workers in Ibadan, Nigeria

SARS-CoV-2 Seropositivity in Asymptomatic Frontline Health Workers in Ibadan, Nigeria

A negative covariation between toxoplasmosis and CoVID-19 with alternative interpretations

High SARS-CoV-2 seroprevalence in Health Care Workers but relatively low numbers of deaths in urban Malawi

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