How Covid-19 has spread in Africa continues to puzzle scientists even as local experts have come up with plausible explanations on the low deaths and infection rate.
A paper authored by experts in Kenya and United Kingdom has suggested weather as one of the reasons behind the low numbers, hence few deaths.
In the paper titled Why is There Low Morbidity and Mortality of Covid-19 in Africa? Kariuki Njenga from Washington State University Global Health Programme – Kenya, and his colleagues support this narrative in relation to the spread of influenza.
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Both SARS-CoV-2 and influenza viruses spread through the same mode of droplets and cause respiratory illnesses.
They argue that Africa experiences warmer and drier weather from December to April season, with average daily temperatures above 20°C in the entire sub-Saharan Africa region and more than 30 of the 46 countries of that region averaging above 25 Celsius.
The sub-Saharan African region has little day temperature variation over the five-months period and throughout the calendar year, decreasing between May and August but still staying above 20°C in most countries.
“It is plausible that this warmer weather is decreasing the transmissibility of SARS-CoV-2 in Africa, as has been demonstrated with other respiratory viruses such as influenza,” the paper reads.
In the paper published in The American Journal of Tropical Medicine and Hygiene on June 1, 2020; the researchers explain that in the cases of influenza viruses, the high disease burden in winter and colder seasons globally is associated with the increased viability of the virus in cold dry conditions.
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Also, the low level of sunlight and the tendency of people to spend more time indoors enhances spread.
Even in equatorial African countries that do not have prolonged seasons of extreme temperatures, the paper notes that influenza cases increase during the cool dry months.
“It is important to note that other aerosol-transmitted viruses that emerged in the recent past, including SARS-CoV-1 in 2002, highly pathogenic H5N1 influenza virus in 2005, and Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, caused few cases in Africa,” reads the paper.
In the early stages of the pandemic, experts had turned into prophets of doom on how the disease will have catastrophic effects in the continent with bodies sprawling all over.
However, several months after the first case was reported on December 31, 2019, in Wuhan, China, of the 418,000 deaths, the continent just has over 6,000 with over 2 million cases.
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“We argue that the low number of cases in Africa may not be an artefact of poor surveillance and low testing because an escalating number of Covid-19 cases would be easily detected through reports of pneumonia clusters at local hospitals, which has not been observed,” reads the paper.
The doomsday report was based on Africa’s unreliable health systems and the burden of HIV, Tuberculosis, and other Non-Communicable Diseases.
The experts probably forgot that the continent has a youthful population which makes the disease less catastrophic with at most mild symptoms to this population.
Uganda, which has the youngest population in the continent with 77 per cent aged below 25, has not recorded any Covid-19 death, with almost 700 cases.
“Africa's more youthful population with a median age of below 20 years when compared with Europe and the United States (median age above 38 years), the paper reads, may have contributed to the low numbers of severe Covid-19 cases and deaths.
“This is a plausible argument, even though its contribution may be less because of other pervasive underlying factors such as malnutrition and risky livelihood and cultural factors brought about by the characteristics of the informal economic sectors they work in, as well as overcrowding within urban settlements,” the paper reads.
The paper notes that a recent study assessing the impact of population age on Covid-19 fatalities found a standardised mortality ratio, which use age-specific CFRs, that was four times less in Africa when compared to Europe and North America and over two-fold less when compared to Asia and South America.
“Because most young persons infected with SARS-CoV-2 are asymptomatic or have mild symptoms that can be missed by targeted surveillance and testing, the contribution of this factor may be better assessed by conducting well-designed prevalence studies to determine the extent of SARS-CoV-2 infections in various settings within the continent,” the paper reads. [Graham Kajilwa]