Africa’s Mild COVID-19 Experience Remains a Puzzle

ADF STAFF

On the list of countries hardest hit by COVID-19, no African nation breaks the top 10.

South Africa, the continent’s hardest-hit nation, is 11th in the world. Below that lie Morocco (30th), Ethiopia (50th), and Nigeria (58th). Other African nations fall farther down the list.

By mid-October, Africa had reported just over 1.5 million COVID-19 cases and 38,600 deaths. By comparison, Europe, which has about 60 percent of Africa’s population, has four times the number of cases and six times the number of deaths.

Why has Africa’s COVID-19 experience been so different?

“We do not have an answer,” Sophie Uyoga, an immunologist at the Kenya Medical Research Institute-Wellcome Trust Research Programme, told Science magazine.

Researchers are weighing a few possibilities: Africa’s young population, its prior experience with epidemics and its urban-rural divide.

Youth and resistance

COVID-19 is deadliest for people in their 60s and older, who often have another illness — what doctors call a comorbidity — that makes the virus more lethal.

Compared to elsewhere, Africans are young. The continent’s median age is 19.7 — about half the median age of Europe and North America and 12 years younger than South America or Asia.

“Younger individuals have fewer comorbidities that would predispose them to severe disease,” Dr. Anne K. Barasa, head of immunology at the University of Nairobi School of Medicine, told ADF.

That may explain why thousands of Africans carry antibodies with no symptoms of COVID-19. One recent study showed that 5% of the households in Nampula, Mozambique, had antibodies with no symptoms.

Babatunde Salako, director general and CEO of the Nigeria Institute of Medical Research, sees another possibility: The immune systems of many Africans may be primed to resist COVID-19.

“The tropical environment that we Africans live in also exposes us to many microorganisms, especially respiratory viruses, which may have similar antigenic surfaces that may have prepared our body for other related viruses like COVID-19,” Salako told ADF.

Immunizations against some of those diseases also may help Africans fend off the virus, he said.

Previous experience

When COVID-19 appeared, African nations deployed epidemiological tools honed by decades of dealing with other disease outbreaks, most recently Ebola.

“Previous experience with Ebola provided an advantage of not starting from scratch in terms of preparations against the pandemic — experienced public health physicians have been tested before in the organization of emergency operating centers, contact tracing and case management of disease outbreak,” Salako said. “This may have made the control of the pandemic easier.”

The eradication of wild polio meant Africa met the pandemic head-on with a network of research labs, community monitoring and public health experts.

“Quarantine and contact tracing were a familiar approach to disease containment,” Dr. Michele Barry, director of the Center for Innovation in Global Health at Stanford University, told ADF.

Urban-rural divide

COVID-19 spreads most effectively in crowded cities. The African countries with the largest caseloads — South Africa, Nigeria, Morocco, Ethiopia — also have large urban populations.

Although cities are growing rapidly, only about 40% of Africans live in them, according to the World Bank. Even in densely populated Malawi, more than 80% of residents live in the countryside, a factor that may reduce the spread of COVID-19 by creating natural social distancing.

“Definitely, less crowding facilitates social distancing due to less interaction amongst large numbers of individuals in the community, which helps to break the transmission cycle of [COVID-19],” Barasa said.

Salako sees an additional benefit from rural life:

“Rural areas boast of living close to nature and may be feeding on naturally occurring or organic foods that may aid immune responses,” he said.

Too few tests?

Africa’s relatively mild experience with COVID-19 may come down to something simpler: Not enough people are being tested.

“These are the reported cases,” Tanzanian epidemiologist Justin Maeda, head of the Africa Centres for Disease Control and Prevention’s Surveillance and Disease Intelligence Division, told the BBC. “When you see the numbers, there are two hypotheses: One, is this is the real observation, two might be the ability to detect the cases.”

Salako’s organization recently joined the ranks of Africa’s government labs and private companies producing tests that can work quickly and cheaply to reveal someone’s COVID-19 status. Salako doubts more testing will create a surge in cases.

“It does not appear more testing will increase cases in Nigeria, as we are now seeing less positive cases at our drive-through center compared with figures five months ago,” Salako said. “We are, however, preparing for any surge in number of cases when schools fully resume. I am not sure we will get a surge, but if it happens, we should be able to deal with it.”