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Alba Iulia
Thursday, September 24, 2020

The COVID-19 pandemic appears to have spared Africa so far. Scientists are struggling to explain why

Health The COVID-19 pandemic appears to have spared Africa so far. Scientists are...

Although Africa reported its millionth official COVID-19 case last week, it seems to have weathered the pandemic relatively well so far, with fewer than one confirmed case for every thousand people and just 23,000 deaths so far. Yet several antibody surveys suggest far more Africans have been infected with the coronavirus—a discrepancy that is puzzling scientists around the continent. “We do not have an answer,” says immunologist Sophie Uyoga at the Kenya Medical Research Institute–Wellcome Trust Research Programme.

After testing more than 3000 blood donors, Uyoga and colleagues estimated in a preprint last month that one in 20 Kenyans aged 15 to 64—or 1.6 million people—has antibodies to SARS-CoV-2, an indication of past infection. That would put Kenya on a par with Spain in mid-May when that country was descending from its coronavirus peak and had 27,000 official COVID-19 deaths. Kenya’s official toll stood at 100 when the study ended. And Kenya’s hospitals are not reporting huge numbers of people with COVID-19 symptoms.

Other antibody studies in Africa have yielded similarly surprising findings. From a survey of 500 asymptomatic health care workers in Blantyre, Malawi, immunologist Kondwani Jambo of the Malawi–Liverpool Wellcome Trust Clinical Research Programme and colleagues concluded that up to 12.3% of them had been exposed to the coronavirus. Based on those findings and mortality ratios for COVID-19 elsewhere, they estimated that the reported number of deaths in Blantyre at the time, 17, was eight times lower than expected.

Scientists who surveyed about 10,000 people in the northeastern cities of Nampula and Pemba in Mozambique found antibodies to SARS-CoV-2 in 3% to 10% of participants, depending on their occupation; market vendors had the highest rates, followed by health workers. Yet in Nampula, a city of approximately 750,000, amere 300 infections had been confirmed at the time. Mozambique only has 16 confirmed COVID-19 deaths. Yap Boum, a microbiologist and epidemiologist with Epicentre Africa, the research and training arm of Doctors Without Borders, says he found a high prevalence of SARS-CoV-2 antibodies in people from Cameroon as well, a result that remains unpublished.

So what explains the huge gap between antibody data on the one hand and the official case and death counts on the other? Part of the reason may be that Africa misses many more cases than other parts of the world because it has far less testing capacity. Kenya tests about one in every 10,000 inhabitants daily for active SARS-CoV-2 infections, one-tenth of the rate in Spain or Canada. Nigeria, the continent’s most populous nation, tests one out of every 50,000 people per day. Even many people who die from COVID-19 may not get a proper diagnosis.

But in that case, you would still expect an overall rise in mortality, which Kenya has not seen, says pathologist Anne Barasa of the University of Nairobi who did not participate in the country’s coronavirus antibody study. (In South Africa, by contrast, the number of excess natural deaths reported between 6 May and 28 July exceeded its official COVID-19 death toll by a factor of four to one.) Uyoga cautions that the pandemic has hamstrung Kenya’s mortality surveillance system, however, as fieldworkers have been unable to move around.

Marina Pollán of the Carlos III Health Institute in Madrid, who led Spain’s antibody survey, says Africa’s youthfulness may protect it. Spain’s median age is 45; in Kenya and Malawi, it’s 20 and 18,respectively. Young people around the world are far less likely to get severely ill or die from the virus. And the population in Kenya’s cities, where the pandemic first took hold, skews even younger than the country as a whole, says Thumbi Mwangi, an epidemiologist at the University of Nairobi. The number of severe and fatal cases “may go higher when the disease has moved to the rural areas where we have populations with advanced age,” he says.

Jambo is exploring the hypothesis that Africans have had more exposure to other coronaviruses that cause little more than colds in humans, which may provide some defense against COVID-19. Another possibility is that regular exposure to malaria or other infectious diseases could prime the immune system to fight new pathogens, including SARS-CoV-2, Boum adds. Barasa, on the other hand, suspects genetic factors protect the Kenyan population from severe disease.

More antibody surveys may help fill out the picture. A French-funded study will test thousands for antibodies in Guinea, Senegal, Benin, Ghana, Cameroon, and the Democratic Republic of the Congo; results are expected by October. The studies will ensure good representation across populations, says Jean-François Etard from France’s Research Institute for Development, who is leading the study in Guinea jointly with a local scientist. And 13 labs in 11 African countries are participating in a global SARS-CoV-2 antibody survey coordinated by the World Health Organization.

South Africa, meanwhile, plans to conduct a number of serological studies both in COVID-19 hotspots and the general population, says Lynn Morris, who leads the country’s National Institute for Communicable Diseases. She notes that antibody prevalence found in the study will likely be an underestimate of true infection rates, given that the virus doesn’t induce antibodies in some people and that antibody levels wane over time.

If tens of millions of Africans have already been infected, that raises the question of whether the continent should try for “herd immunity” without a vaccine, Boum says—the controversial idea of letting the virus run its course to allow the population to become immune, perhaps while shielding the most vulnerable. That might be preferable over control measures that cripple economies and could harm public health more in the long run. “Maybe Africa can afford it,” given its apparent low death to infection ratio, Boum says. ”We need to dig into that.”

But Glenda Gray, president of the South African Medical Research Council, says it could be dangerous to base COVID-19 policies on antibody surveys. It’s not at all clear whether antibodies actually confer immunity, and if so, how long it lasts, Gray notes—in which case, she asks, “What do these numbers really tell us?”

Source: Sciencemag

14 COMMENTS

  1. Nature always has a way of providing answers, just don’t stop looking.
    Most people were prophesying that Afrikans, compounded by the soiled health systems, will be dying like rats. It has baffled observers that even the weakest can survive the thicket.

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  2. When God protects a people, Jesus is the reason. With that said the whole of Africa should now take preventative measures by boisterous medical training. Also start inter country trade. Protect Africa from Asian and European greed, their multinationals and eroded morals.

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  3. The evil diasporans are also scratching their heads. Remember these monkeys in diaspora like tarino were here daily criticising dr chilufya and praying that many would perish. Funny enough it so happened that it’s their colonial masters countries that were badly affected. Good riddance for stupldlty

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  4. Let’s make this one thing clear — the trial of Jesus had nothing to do with dying for our sins and everything to do with politics. There is evidence that Jesus was a descendant of Kind David and thus the real king of Jews. It’s more than likely that he was brutally murdered because of that.

    Even if you find it hard to believe this, it’s no secret that Jesus’ death was politically motivated. We know he died because of the corrupt leaders of the corrupt society and their sins. It’s that simple, like things usually are. The simplest explanation is usually also the one that makes most sense.

    And the political explanation here sure makes a lot more sense than some elusive notions of ‘dying for our sins’ on the cross and thus ‘saving the world.’ If anything, the world hasn’t been saved,…

  5. Coronavirus a hoax! It’s the biggest scam in history of mankind..Brainwashed society believes everything, they just accept brainwashing as the standard.

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  6. We are not tasting enough; only South Africa is and that the reason they are at half a million. To understand the impact on Africa, like every disease, you have to look at statistics from countries with huge black population like USA, UK and Brazil.

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  7. They should question the TESTS. There may be cross reactivity with other infections that are endemic in Africa. Besides, if the SARS-Cov are bat viruses, Africans may have got entangled with them long time ago. The other issue to look into is virulence of the virus in Africa as well as antibody cross reaction. For example, the sickle cell gene offers some resistance against malaria. Northern Europeans have some resistance against HIV. All these questions may have to be looked into.

  8. This a lesson to most Africans with inferiority complex like HH Chik4l4 to know that Africa should sort out African problems on its own. The likes of HH are the ones who sold fellow African for slaves. This privatization thief needs to be taught a lesson.

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  9. ?Nzelu?you are a warped lowlife . You use Jesus name and then become Xenophobic.
    Read your comments. All who voted for his comments are also xenophobic.

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