COVID-19: the case of Africa
The dampened course of COVID-19 in Africa may reveal innovative solutions to be explored. Demographics, genetic inheritance, early and severe containment measures seem to be some interesting avenues for further investigation. At least, this is what an international group of scientists, including researcher Benjamin Dewals from the FARAH (Veterinary Medicine), has proposed in an opinion published in the scientific journal Science.
S
ARS-CoV-2, the coronavirus responsible for COVID-19, has spread rapidly and widely in most countries of the world, with significant mortality in Europe and the United States. While experts had predicted millions of deaths from the disease in Africa, it now turns out that the predicted figures have still not been reached. While it is not entirely certain that Africa will be spared by this pandemic, certain factors, notably genetic, demographic or immune factors, could explain the lower impact of the virus on African populations. In any case, these are some of the paths of reflection put forward by a group of scientific researchers including Benjamin Dewals, immunologist and FNRS Researcher Associate at the ULiège FARAH research unit. To reach to these conclusions, the researchers put on the table several data or characteristics specific to Africa that could have contributed to the slowing down of the pandemic.
Demographic, immune and genetic factors may be one reason why the disease has had less impact. The African population is much younger than those in the United States or Europe (average age 19.7 years in Africa and 38.6 years in the USA)," explains the researcher, "but we know that the virus is much more devastating in older populations while younger populations develop very few symptoms. "A more rapid development of "herd immunity" in the younger population may also have led to a decrease in severe cases. Antibody tests (serosurveillance) have yet to be performed and analyzed, but they could determine whether transmission was more widespread with a high rate of asymptomatic and mild cases in these countries than on other continents.
The genetic characteristics of the coronavirus (SARS-CoV-2) and human genetics could also be among the reasons for the low incidence of COVID-19 in Africa. "The effectiveness and adequacy of adaptive responses to viral infections depend on multiple factors, including past or present infections with other pathogens. Therefore, it is possible that previous exposure to related human coronaviruses could generate immunological cross-reactivity. "Another hypothesis, related to the immune response, suggests that early and chronic exposure to endemic unrelated pathogens leading to immune cell activation in challenging environments, such as those found in Africa, induces a strong regulatory immune response to dampen excessive inflammation, as in the case of SARS-CoV-2.
Measures such as testing, curfews, school closures and travel restrictions that were taken earlier than in Europe or the United States could explain a decrease in the number of imported cases and a reduction in transmission within African countries, that would have given the authorities sufficient time to prepare the already stretched laboratories for diagnosis and to develop strategies for quarantine, contact tracing and social distancing in a continent that already has experience of these practices to control epidemics such as Lassa fever and Ebola. “It is clear that containment measures have not been followed in many countries," says Dewals, "and it is also unclear whether the release of these measures will lead to an increase in the number of cases. »
There are differences of opinion regarding the pattern of spread of COVID-19 in Africa compared to Europe or the USA, as there is still a lot of data missing (asymptomatic cases, antibodies, etc.), but the authors believe that Africa should be included in the research programmes on COVID-19. "The COVID-19 pandemic should highlight the need for the widespread implementation of public health tools such as high-quality data, accurate diagnostics for tracking and tracing, good communication and effective vaccine. Rapid testing of vaccines in different parts of Africa is essential, as high levels of exposure to pathogens can limit vaccine responses, he concluded. »
The first trials of the COVID-19 vaccine are beginning in South Africa (VIDA trial of the Ox1Cov-19 vaccine) and more are planned. It is hoped that this will stimulate Africa's full participation in the fight against the pandemic.
Scientific reference
Moustapha Mbow, Bertrand Lell,Simon P Jochems, Badara Cisse, Souleymane Mboup, Benjamin G. Dewals, Assan Jaye, Aalioune Dieye, Maria Yazdanbakhsh, COVID-19 in Africa : Dampening the storm. The dampened course of COVID-19 in Africa might reveal innovative solutions. Insights, Science, august 2020.
Contact
FARAH (Fundamental and Applied Research for Animal & Health) | Faculty of Veterinary Medicine
