Capturing the complexity of COVID-19 in sub-Saharan Africa

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The global experience of the COVID-19 pandemic has sometimes appeared to have one notable exception, with confirmed cases and deaths in Africa being considerably lower than elsewhere. Governments in sub-Saharan Africa (SSA) were praised for swift actions early in the pandemic, while some scientists suggested that the warmer climates and younger populations of the region may have kept infections down.

However, a comprehensive modelling study has revealed the large diversity of factors driving the pandemic across countries with different demographics, healthcare capacities and human mobility. The study, by researchers in South Africa, Madagascar, US, UK and France, suggests that climatic variation across SSA had little effect on early outbreaks. Instead, it contends that connectivity between communities can better explain the spread of the virus.

The biggest challenge in understanding the scope of COVID-19 in SSA is that testing levels have generally been lower than in the global north, and vary hugely between countries, as do accurate death reports.

“The cost for COVID-19 testing might seem minimal to middle- and high-income countries, but poorer countries cannot afford to test large numbers of people,” says Villyen Motaze at Stellenbosch University in Cape Town, South Africa, who previously worked with public health specialists and policymakers across Africa as a medical epidemiologist at the National Institute for Communicable Diseases in Johannesburg.

Thanks to the experience of Motaze and co-workers, including Antso Raherinandrasana, the head of epidemiological surveillance at Madagascar’s Ministry of Health, the team gathered huge datasets on factors including age, climate, household size and preventive measures such as handwashing. To model the connectivity of regions, they considered international flights and the mean travel times to large cities. Their exhaustive analysis, using several different modelling approaches, revealed that there are few, if any, consistent driving factors across the region.

“It seems unlikely that we would generalize across Europe for example, and yet there are those that seem quick to generalize across SSA and its 48 distinct nations,” says Benjamin Rice from Princeton University, US, and lead author on the group’s paper, published in Nature Medicine. “We found that even if we assumed high rates of under-reporting of cases and deaths, and adjusted our estimates accordingly, the number of infections is still likely to vary greatly between SSA countries.”

The study did, however, show that climatic factors such as temperature and humidity had very minimal effects on epidemic peaks, defying previous assumptions that Africa’s more tropical environment could reduce infections.

“This idea should be dropped,” says Fidisoa Rasambainarivo, another of the paper’s authors based at Princeton and Mahaliana Labs in Antananarivo, Madagascar. “Modelling work clearly indicates that climate does not constitute the protective factor we were hoping for.”

Instead, the simulations show that levels of connectivity are probably more likely to account for variance in viral spread across SSA. Therefore, future efforts to manage the pandemic should consider local patterns of travel, age, other illnesses and access to care. These should also influence the rollout of vaccines because, as Rice says, “the lack of equity in vaccination occurring at the moment is indefensible.”

“Following the many variations in risk factors revealed in our article, vaccination coverage and protection will likely be heterogeneous within and between countries,” says Rasambainarivo. “Scientists need to work with authorities to minimize those differences, because they will have consequences for the pandemic globally.”