Africa Has Held Off the Worst of the Coronavirus. Researchers are Working to Figure Out How.

The reasons are still something of a mystery, but scientists said the success of many African countries offers crucial lessons.

Pedestrians, some wearing protective masks, in downtown Kampala, Uganda, on June 23.Esther Ruth Mbabazi / Bloomberg via Getty Images

Sept. 25, 2020, 10:44 AM EDT

By Denise Chow

When the coronavirus first began spreading around the world, there was near-universal concern among experts that countries in Africa could be hit particularly hard, with high rates of transmission that could quickly overwhelm health care systems.

But roughly nine months into the pandemic, which has sickened over 31 million people and caused more than 950,000 deaths around the world, most African countries have fared significantly better than other parts of the world. The reasons are still something of a mystery — more research is needed, and some studies that aim to answer the questions are only just beginning — but scientists said the success of many African countries so far offers crucial lessons for the rest of the world and shine a light on how inherent biases can distort scientific research.

"The initial disease prediction models painted a very bleak picture of severe devastation of lives and economies in Africa," Dr. Sam Agatre Okuonzi, who works at Arua Regional Referral Hospital in northern Uganda, said Thursday in a World Health Organization news briefing. "In Uganda, it was predicted that by September, there would be 600,000 cases of Covid-19 and 30,000 deaths. But the reality is starkly different."

Uganda has 7,064 reported coronavirus cases and 70 deaths, according to a Johns Hopkins University tally. South Africa, the hardest-hit country on the continent, has recorded more than 665,000 cases and 16,206 deaths. That represents about 28 deaths per 100,000 people, compared to more than 61 deaths per 100,000 in the U.S.

Yet even though other countries, such as Ethiopia, Algeria and Nigeria, have struggled with bigger outbreaks, most countries on the continent have succeeded so far in containing the virus's spread.

Part of that success owes to aggressive measures enacted early in the pandemic to restrict people's movements and slow transmissions within communities, said Dr. Matshidiso Moeti, the WHO's regional director for Africa.

"Governments took early, quite drastic action through the lockdowns at great cost to their economies," Moeti said in the briefing. "This has bought us some time."

She said there are concerns that numbers of new infections could spike in the coming weeks as restrictions are eased and many African countries slowly return to normal. Moeti said upticks are already being observed in South Africa, Algeria, Mauritania and Ghana, likely as a direct result of the reopening of cities in May and June.

The WHO has stressed that the next few months — in Africa but also elsewhere — will be very important to stave off an anticipated second wave of infections.

Moeti said African countries should emphasize preparedness and must "put in place the public health capacities to contain the spread, so we don't have wide spread repeating itself in cycles."

As efforts to prepare for a possible second wave get underway, scientists are also trying to learn what African countries did right in the first phase of the pandemic.

More research is needed, but some early theories have emerged, Okuonzi said.

He said it's possible that some African countries are better equipped to respond to infectious disease outbreaks "because we have a lot of experience from Ebola and other diseases."

Shaun Truelove, an assistant scientist and modeling expert at the Johns Hopkins Bloomberg School of Public Health, said it's also possible that some populations in Africa could have "cross-reactive immunities" from having been exposed to other circulating coronaviruses.

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There's no firm evidence of that yet, but it's something researchers are actively studying. Francisca Mutapi, a professor of global health infection and immunity at the University of Edinburgh in Scotland, is involved with research in Zimbabwe to assess people's immunity levels to six other known coronaviruses. Mutapi said she expects to know more about any potential cross-protections in the next four months.

Mutapi suggested that differences in culture and lifestyle could play a role. "One of the factors about the virus is it doesn't transmit very well outdoors," she said. "Africa has a significant population that is rural and spends a lot of time outdoors. That is one of the factors that we have found from our own work."

Moeti said it's also likely that demographics could explain why many African countries have had fewer Covid-19 deaths.

"In most African countries, we have about 3 percent of the population aged over 65 years," she said, adding that research has shown that young people are at lower risk of becoming severely ill from the coronavirus.

The trends in Africa stand in stark contrast to the experiences of African Americans, who, due to a range of other socioeconomic factors, are at a disproportionate risk of becoming severely ill from the coronavirus. Researchers have no reason to believe that Black people have a natural immunity to the coronavirus, despite some pseudoscience that has circulated about Black people in the U.S. The U.S. does, however, have a history of race- and socioeconomic-based health disparities.

Some researchers have raised the possibility that low numbers in Africa could be a result of underreporting, but Truelove said that's not likely to be the main reason.

"That doesn't fully explain it, because we would see health care systems being overwhelmed if there truly was an outbreak occurring," he said.

Scientists like Truelove are eager to learn more about what has so far kept African countries from realizing the dire predictions from early on in the pandemic.

"It's really not clear why and if it's a combination of all these theories or other things, as well," he said. "It's going to be an interesting discovery process."

But beyond epidemiological concerns, the disconnect between early projections for what could happen in Africa and most of the continent's real-life experience exposes the limits of conventional infectious disease modeling, Okuonzi said.

Most models are "based on European populations, not on African populations, and they are also informed by very well-entrenched biases about Africa, that, for example, Africa is prone to disease," he said. "Covid-19 has shattered a lot of biases about the disease in general."

Denise Chow is a reporter for NBC News Science focused on the environment and space.