Scientists link genes to lower Covid deaths in Africa
Source：The Star
From：Taiwan Trade Center, Nairobi
Update Time：2021/10/14
COVID TEST: Aga Khan University Hospital laboratory technologist Kennedy Wafula during a free Covid-19 PCR testing on August 17 in Mathare. Image: MAGDALINE SAYA
In a new paper, scientists from Kenya, the United States and Europe theorise that trained immunity and genetics could be playing bigger role than is being acknowledged.
However, they note the main factors that have helped the continent are most likely the early government containment actions.
Genetic factors could still explain the marked discrepancy between Covid-19 infection in Africa and confirmed deaths, scientists say.
The lethal Delta variant is now the most dominant strain on the continent. However, Covid-19 cases are reducing in most African nations without causing any havoc like in India.
Delta is 200 per cent more transmissible than the original Wuhan strain and 97 per cent of all cases reported in Kenya are now Delta, compared to 52 per cent in India.
In a new paper, scientists from Kenya, the United States and Europe theorise that trained immunity and genetics could be playing a bigger role than is being acknowledged.
“Some genetic immunological factors could possibly be playing a role in shielding Africa from the brunt of the pandemic,” they say in the paper.
“What Could Explain the Lower Covid-19 Burden in Africa despite Considerable Circulation of the Sars-CoV-2 Virus?”
Africa has so far accounted for just 3.5 per cent of lab-confirmed cases, despite containing 12.5 per cent of the global population.
The continent’s share of deaths is just 4.1 per cent of the reported globally. “These numbers significantly defy early predictions of mass Covid-19 catastrophe,” they said.
The study is published in the International Journal of Research and public health.
Notably, African countries with less indigenous (non-African) gene pool are more affected, for instance, Algeria and Egypt because of Arabian influence and South Africa because of European Influence.
The scientists explain that Sars-CoV-2 infects human cells largely through its interactions with the ACE2 receptor, involved in regulating blood pressure dynamics.
“African people have been shown to respond less effectively to ACE inhibitors for the treatment of blood pressure, and have less expression of ACE2; therefore, there is potential for a more difficult route that the virus must maneuver to infect cells in this population,” they say.
They also point to studies that show blood group A as having the highest risk of Covid-19-associated respiratory failure, with group O having the lowest risk.
“Studies have shown that African populations have a particularly high proportion of O-positivity at nearly 50 per cent, which is higher than in White and Asian populations,” the authors say.
However, this hypothesis has been challenged by the particularly heavy Covid-19 burden in unvaccinated African Americans in the US, who would likely share some or most of these genetic advantages.
The authors explain that the elevated levels of non-communicable diseases in African Americans than in continental African populations could help explain this discrepancy along with other adverse socioeconomic and cultural factors.
However, they note the main factors that have helped the continent are most likely the early government containment actions.
Others are the young population, trained immunity from other infectious diseases, and the largely outdoor lifestyle.
Source: https://www.the-star.co.ke/news/2021-09-07-scientists-link-genes-to-lower-covid-deaths-in-africa/