Coronavirus: Unpacking the theories behind Africa’s low infection rate
Two months after the first coronavirus cases burst onto the scene in Africa, the disease seems to be spreading more slowly on the continent than elsewhere. What factors could be behind this apparent resilience?
It’s not yet the moment to declare victory, but all the same, the statistics are compelling: while Africa’s first COVID-19 cases were detected in mid-February, today the continent is only reporting 47, 118 cases and 1,843 deaths, compared with more than 3.6 million cases and over 252,102 deaths worldwide.
Statistically speaking, Africa is an outlier.
The continent, which is home to 17% of the world’s population, accounts for only 1.1% of cases and 0.7% of deaths. Even better news: with more than 12,000 recovered patients already, Africa appears to be more resistant to the coronavirus than other continents.
Is this simply because the disease arrived later on the continent and, as a South African study which projects the disease’s peak to come in September suggests, the worst is still ahead? For the time being, at any rate, no one is denying anymore that the virus seems particularly slow to spread on the continent. Read on to learn about the main theories being put forward to explain this phenomenon.
This is the most common explanation given. Like the flu, the coronavirus is believed to be a disease that thrives in the winter months and is not very resistant to heat, dry conditions or direct sunlight.
The theory appears to be corroborated by the fact that the countries most impacted by the pandemic have rather temperate climates and that the majority of cases are concentrated in either the far north or the southernmost regions of the continent, where heat and dry conditions are less extreme.
On the research front, a British study confirmed that respiratory diseases are on average less common in hot, dry countries (what’s more, the only severe SARS-type outbreak to have affected the continent occurred in Cape Town between 2002 and 2003), and a US report dated 24 April found that the virus’s half-life, i.e., the time it takes for the virus’s infectious potential to become reduced by half, can drop from 18 hours to 6 hours when temperature and humidity increase.
However, researchers like Pierre-Marie Girard, Vice President of International Affairs at the Pasteur Institute, remain very cautious. He has emphasised the fact that during in vitro experiments he observed that the coronavirus “multiplies without problem in the heat”.
Africa’s young population is the second most common explanation given. In English-speaking countries, there is even a slogan about it: “The virus is old and cold and Africa is young and hot.”
Doctors have confirmed that the majority of severe COVID-19 cases involve people over age 60, which is a stroke of luck for the continent given that the median age of its population is 19.4 years and that 60% of the population is under age 25.
It has also been pointed out that in one of the hardest hit countries, Italy, 23.1% of the population is over age 65, versus 5% in Africa.
In certain countries on the continent, people eat bats and live on top of one another…in fact, all the conditions for a disaster are reunited, but we haven’t seen one happen.
This theory has virtually unanimous support, but scientists temper it, reminding us that although the African population is young, it is also unfortunately more impacted than others by diseases such as HIV and malnutrition, which can make Africans more vulnerable.
Lastly, some researchers have drawn attention to the fact that in Europe and the United States, elderly people often live in proximity to one another in retirement homes, which promotes the spread of the virus, whereas in Africa they live more often than not with their family, which may help protect this age demographic.
Lower population density
With the exception of a few countries like South Africa, Egypt, Morocco and Algeria, and certain large metropolitan areas, population density is lower in Africa on average than in other parts of the world where the coronavirus has been the most devastating, like in Western Europe and North America. Africa has an average of 42.5 inhabitants per square kilometre, compared with 207 in Italy and 275 in the United Kingdom.
The World Health Organization (WHO) has confirmed this positive factor, while also underlining that these figures are just an average, and that cities like Lagos and Abuja have record-breaking population density.
Another rational, hard to avoid explanation: Africans travel less, on average, than the populations of most developed countries, and as a result infection risks are inevitably greatly reduced.
In addition, just one African airport – that of Johannesburg – features in the list of the 50 busiest airports in the world.
Experience with epidemics
Many have highlighted the fact that this isn’t the first epidemic Africa has experienced; it’s been through a number of more deadly ones. For instance, Ebola.
Health care personnel but also populations therefore have a certain familiarity with health crisis situations, lessons have been learned and “best practices” implemented.
Certain detection, patient isolation and precautionary methods developed when caring for patients during past epidemics can be reused to fight the coronavirus. African authorities also took stock of the danger more quickly than others and implemented very early on border closures as well as social distancing and lockdown measures.
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As for the WHO, officials there have underlined that following the Ebola epidemics in West Africa, 40 countries on the continent were given support to assess their response capacity. Then, 35 of these countries were provided with financial assistance to improve their health care systems.
Of course, the situation is far from perfect – particularly with regards to research and testing laboratories – but, for Dr Moumouni Kinda, who has faced several crises alongside the NGO Alliance for International Medical Action (ALIMA), “epidemics like Ebola enabled us to accumulate experience on communication and awareness-raising, which are key points in breaking the chains of transmission of the virus”.
Effective cross-border cooperation
For some African scientists, the continent also has the advantage of practicing genuine solidarity. When a country lacks masks or testing kits, less impacted neighbouring countries are likely to supply a needy country with them.
Lesotho, which doesn’t have a functioning laboratory, has its swabs tested in South Africa, and the African Network for Influenza Surveillance and Epidemiology (ANISE), used to tackle COVID-19, currently brings together more than 30 of the continent’s countries.
Without being naively optimistic, the reality is that solidarity sometimes appears to work better in African nations than in other, more wealthy countries, where major laboratories jealously guard over their discoveries in the hope that they will be able to market a treatment or a vaccine. And then there’s US President Donald Trump’s attempt to get his hands on drug patents under development for the sole (financial) benefit of the United States.
On a much more local scale, it has also been pointed out that the community-based lifestyle of many African populations facilitates the spread of prevention messages and helps detect sick individuals more rapidly, as few people are likely to be left to their own devices.
Indirect protection from other treatments
This theory has stirred much controversy and the WHO, in particular, is very wary of the idea. However, certain doctors have observed some compelling coincidences: there are less coronavirus infections in the countries most impacted by malaria or tuberculosis. The same holds true for countries that vaccinate much of their population with Bacillus Calmette-Guérin (BCG).
Does the fact that people have already developed certain illnesses protect them from COVID-19? It will take time to prove this theory, but many doctors think that antimalaria treatments like chloroquine have a certain amount of effectiveness. Given that a lot of people have been treated with these drugs in Africa, a resistance could be present.
This is partly why French Professor Didier Raoult, but also research teams such as the Drug Discovery and Development Centre (H3D) at the University of Cape Town are prioritising the testing of antimalaria drugs.
The WHO has been critical of this approach, noting that certain countries like Burkina Faso, Nigeria and Senegal, where malaria has taken a toll, have not been spared by the virus.
The organisation also cautions those who think that the pneumonia vaccine can protect them, but encourages, on the other hand, people to get a flu vaccine where possible, as flu symptoms are quite similar to those of COVID-19.
And what if Africans were protected by their DNA which, for a reason that remains to be determined, is better able to withstand the coronavirus? The theory has not at all garnered unanimous support – at the Pasteur Institute, Girard “doesn’t really see why” such a specificity would exist – and it will take time to explore the idea.
Professor Christian Happi, a Cameroon national and genomics expert who divides his time between Harvard University and Nigeria, hasn’t completely ruled out the possibility: “Africans are exposed to a lot of diseases, so it’s possible that their body reacts better. We need to find the antibodies to confirm this, but it’s possible. After Ebola, we observed that many people in Nigeria were exposed to the disease but never developed it.”
A viral mutation
This idea is closely related to the previous one: since it currently appears that several different strains of COVID-19 (up to eight distinct types) are circulating worldwide, then perhaps the strain present in Africa is less aggressive.
This would also explain the fact that there seem to be more asymptomatic cases on the continent than elsewhere. The theory remains bold insofar as the virus entered Africa by way of patients who caught it outside the continent.
Did the virus mutate after it arrived? The WHO has not ruled out the idea, but stresses that to prove it, a whole-genome sequencing of COVID-19 needs to be conducted (which is currently underway).
When examining the specific features that could give Africa an advantage, Matshidiso Moeti, WHO Regional Director for Africa, underlined the fact that the continent “has a very active and skilled textile industry”, particularly in Brazzaville, where the organisation’s regional office for Africa is located.
This particularity perhaps allows the population to benefit from more and better-quality cloth masks than in certain wealthy countries where shortages are the norm.
Bottom line: Scientists highlight that what is likely behind the continent’s low caseload is, first and foremost, the fact that most countries implemented draconian protective measures very early on.
Another potential explanation is the fact that the disease affected travellers first. Generally better informed than the average citizen and most often living in cities, the first cases were easier to identify than in other epidemics.
However, the low caseload continues to surprise, as Francine Ntoumi, a Congolese biologist, commented: “In certain countries on the continent, people eat bats and live on top of one another…in fact, all the conditions for a disaster are reunited, but we haven’t seen one happen.” It’s up to scientists to find out why, she said.