When the Covid-19 pandemic threat emerged earlier this year, many Anxiety About what happens when it reaches Africa.Concerns about the combination of over-funded and under-funded healthcare systems and the existing burden of infectious and non-infectious diseases often brought about it. talked In apocalyptic terms.
But that didn’t happen at all. September 29, the world passed Reported 1 million deaths (actual numbers will of course be higher). On the same day, count The cumulative total for Africa was 35,954.
Africa Account It accounts for 17% of the world’s population, but only 3.5% of the reported deaths from Covid-19 worldwide. All deaths are important and clearly a small number should not be underestimated. Of course, the quality of the data collected in such a wide range of countries varies, but the gap between what is predicted and what actually happened is staggering. There has been much debate about what explains this.
As the leader of the Covid-19 team at the African Academy of Sciences, we have followed the events and explanations that are taking place. The new situation is that infection rates are high in many African countries, but severity and mortality are much lower than initially predicted based on experience in China and Europe.
Given the large fluctuations in the situation across the continents of 55 countries, the exact contribution of any one factor can fluctuate.
We argue that Africa’s much younger population explains a very large part of the apparent difference. Part of the remaining gap is probably due to poorly reported events, but there are many other plausible explanations. These range from climatic differences, existing immunity, genetic factors, and behavioral differences.
Given the large variability in conditions across the continent, including 55 member states, the exact contribution of one factor in a particular environment can vary. But the bottom line is that what initially seemed to be a mystery becomes less mysterious as more and more research evidence emerges.
The importance of age
The most obvious factor in low mortality is the age structure of the population.Risk of Covid-19 death for people over 80 in multiple countries Around 100 times more than people in their 20s.
This is best understood in a particular example. UK as of September 30 Was reporting In contrast, Kenya reported 691 deaths, a specific Covid-19 death toll of 41,980.
Correcting the population size, Kenya’s death toll was expected to be about 32,000. However, if we also modify the population structure (assuming that the UK age-specific mortality rate applies to Kenya’s population structure), Would expect About 5,000 people died. There is still a big difference between 700 and 5,000. What is the cause of the remaining gaps?
Other possible contributors
One possibility is the failure to identify and record the death.
Kenya, In most Initially, countries have little testing capacity and certain death registrations are difficult.But kenya Build immediately Due to its testing ability and special care to find death, this size gap is less likely to be fully explained by the lack of information.
There is no shortage of ideas for other factors that may be contributing.
Recent large-scale multilateralism Investigation In Europe, mortality has been reported to have declined significantly in connection with rising temperatures and humidity. The authors hypothesized that this may be due to the mechanism by which the airways clear the virus, which works better in warmer, humider conditions. This means that people may have fewer virus particles in their system.
However, Systematic review of global data – While confirming that warm and moist climates appear to reduce the prevalence of COVID-19 – we have shown that these variables alone cannot explain most of the variability in disease transmission. It is important to remember that there are significant weather fluctuations throughout Africa. Not all climates are warm or humid. If it is warm or moist, it may not last throughout the year.
Other suggestions include Possibility of existing protective immune response due to previous exposure to other pathogens or previous exposure to other pathogens BCG vaccination, A vaccine against tuberculosis provided at birth in most African countries. A large analysis of 55 countries, which make up 63% of the world’s population, shows a significant correlation between increased BCG coverage at a young age and better results for COVID-19. I did.
Genetic factors may also be important. A Recently explained Haplotypes (groups of genes) that are present in 30% of the South Asian genome and 8% of Europeans are rarely present in Africa, associated with an increased risk of severity.
The role of these and other factors, such as potential differences in social structure and mobility, is subject to ongoing research.
More effective response
That’s an important possibility Public health measures Many African countries prepared by previous experiences (outbreaks, epidemics, etc.) were simply more effective in limiting infection than in other parts of the world.
But in Kenya Estimate The epidemic actually peaked in July, infecting about 40% of the urban population.Similar photo Is appearing In other countries. This means that the measures taken had little effect on the virus infection itself, but herd immunity may play a role in limiting further infections.
At the same time, there is another important possibility.The amount of virus (the number of virus particles that infect a person) is Important determinants Of severity.It has was suggested The masks reduce viral load and their widespread wearing may limit the likelihood of developing severe illness. WHO recommends wearing a mask, but intake fluctuates and is low for many European countriesCompared to many parts of Africa..
So is Africa clear? Well, obviously not. There are still many viruses around, and we don’t know what will happen as the interaction between the virus and humans evolves.
But one thing is clear: the secondary impact of a pandemic will be a real Covid-19 challenge in Africa. These result from severe interruptions in social and economic activity and potentially catastrophic consequences. Decrease in service provision It protects millions of people, including regular vaccinations, malaria, tuberculosis and HIV control programs.
Research subject
The main impact of the new situation is the need to reassess the African Covid-19 research agenda. Many of the initially identified priorities may still be retained, but their relative importance may have changed. The important thing is to address the current problem, not the one that was imagined six months ago.
The same applies to public health policy. Of course, basic measures such as hand washing are still essential (regardless of Covid-19) and you should continue to wear the mask no matter what the level of Covid-19 infection. However, other measures that have a broad impact on society, especially restrictions on educational and economic activities, should be continually reviewed.
The key now is to strengthen monitoring and ensure that flexible response is driven by high-quality real-time data.
Kevin Marsh, Professor of Tropical Medicine, Oxford University And Moses Arobo, Program Manager of Grand Challenges Africa, African Academy of Sciences
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