The WHO reports on August 7 that more than 1 million infections have been registered in Africa, citing a tipping point. Still, the number of sick and dead on the continent is relatively low. How is that possible? In an article in Science, researchers from the Leiden University Medical Center (LUMC) and partners in Africa describe possible causes. They suggest that the different structure of the immune system may play a role in the relatively low COVID-19 mortality rates in Africa.
Many predicted a very murky scenario for Africa with millions of COVID-19 deaths, according to the authors. After all, many African countries are struggling with poverty, poor health systems and unsanitary conditions. However, factors such as lockdowns, banning large gatherings, the relatively young population, and less diabetes and cardiovascular disease likely contributed to the low COVID-19 death rates to date.
Exposure to microorganisms and parasites
According to LUMC LEaDing fellow Simon Jochems and LUMC professor of Parasitology Maria Yazdanbakhsh and their co-authors, something else plays a role in the low death rate in Africa compared to other parts of the world.
Yazdanbakhsh: “Together with our partners in low- to middle-income countries, we have shown that the immune systems of people living in rural areas look very different. This is not only due to genetics, but mainly due to environmental factors, such as intensive exposure to micro-organisms and parasites. In that light it is striking that South Africa, the most developed country, has more than half of the COVID-19 cases in Africa.
Immune system very different
Previous research has shown that the immune system of someone living in the Netherlands is very different from a person of the same age and gender in Senegal, Gabon or Indonesia. But more importantly, someone who lives in the urban area of these countries has a different immune system than a genetically similar person who lives in a rural area of the same country.
“An abnormal immune system also means an abnormal response to SARS-CoV-2. For example, one of the immune cells in the lungs that triggers the harmful cytokine storm in Africans can be better regulated and thus cause less havoc when infected with SARS-CoV-2, ”explains Jochems. He is an expert in mucosal immunology and in particular of the respiratory tract.
Africa in the COVID-19 Investigation Roadmap
Africa should therefore be included in the global roadmap of COVID-19 research, says Yazdanbakhsh. “Understanding the variability in the epidemiology of COVID-19 and identifying the key factors contributing to the course of the pandemic can help us develop innovative policies, treatments and vaccines that will drive the global fight against this and possibly help future pandemics. ”
“What contributes most to the course of COVID-19: social distancing, ban on large gatherings, socio-economic segregation or hand washing? Why is young age protective? Which cells or signals in the immune system need to be activated to prevent an excessive immune response? Multisectoral research to find the answers to these questions provides us with the knowledge we need to stop the pandemic. ”
LUMC Global programma
The long-term relationships between the LUMC and African research partners were essential for publishing these insights. Yazdanbakhsh: “To understand global health problems, close collaboration with researchers in continents such as Africa is indispensable.” The LUMC is therefore investing extra in international outreach through the LUMC Global program.
For more information, read the paper ‘COVID-19 in Africa: dampening the storm?’ in Science.