And although Africa's handling of the pandemic has received scant global attention so far, experts worry the virus may ravage countries with weak health systems and a population disproportionately affected by HIV, tuberculosis (TB), and other infectious diseases. "Social distancing" will be hard to do in the continent's overcrowded cities and slums.
"We really have no idea how COVID-19 will behave in Africa," says pediatrician and HIV researcher Glenda Gray, president of the South African Medical Research Council. Last month, World Health Organization Director-General Tedros Adhanom Ghebreyesus, who is Ethiopian, said his "biggest concern" was COVID-19 spreading in countries with weak health systems.
Sub-Saharan Africa detected its first case only on 27 February, in an Italian man who had traveled to Nigeria. Most other cases since then were imported from Europe; fewer came from the Americas and Asia. But until today, there were no examples of community spread.
That's not simply because of a lack of testing. More than 40 countries in Africa now have the ability to test for COVID-19, up from only two during the early stages of the outbreak in China. But the focus of African COVID-19 surveillance has been at countries' points of entry, and testing has targeted people with a recent travel history to outbreak areas abroad. However, screening passengers for fever has shown to be largely ineffective, because it doesn't catch people still in their incubation phase-up to 14 days for COVID-19. It also won't detect cases that occur in African communities. "I do think that cases are slipping through the net. There is an urgent need to investigate and address this point," says Francine Ntoumi, a parasitologist and public health expert at Marien Ngouabi University in the Republic of Congo.
One way to find out whether the disease is spreading in the community is by looking at patients presenting with flulike illnesses at clinics and hospitals. The number of such patients isn't increasing yet in Durban, which is in KwaZuluNatal, the province with South Africa's highest HIV infection rate, says Salim Abdool Karim, director of the Centre for the AIDS Programme of Research in South Africa. Nor are they seeing a rise in older patients with acute respiratory distress. "Based on this, I feel reasonably confident that we do not have widespread community spread that is undetected," Abdool Karim says.
But he thinks it's just a matter of time before imported cases of COVID-19-most of whom would be relatively wealthy people who can afford to travel-trickle down to the country's most vulnerable communities. Patients who came from Europe will likely have interacted with South Africans prior to their diagnosis, including household help, who often take crowded minibuses to their homes in low-income areas-perfect conditions for COVID-19 to spread. "I think it is inevitable that we will have a substantial epidemic," Abdool Karim says.
Another way to reality-check reported COVID-19 cases is to scour surveillance systems that track influenzalike illnesses for unusual spikes. The Global Influenza Surveillance and Response System is showing elevated levels for some African countries, says John Nkengasong, director of the African Centres for Disease Control and Prevention (Africa CDC), which is based in Addis Ababa, Ethiopia. But that might be for reasons other than COVID-19, he says, like improvements in the quality of surveillance data. It's also unclear how sensitive such detection methods are. In the United States, where the reported caseload is much higher than in Africa, scientists are seeing potential signals in data sets tracking influenzalike illness in older age groups, which are disproportionately afflicted by COVID-19, says Yale University epidemiologist Dan Weinberger. "But whether that is disease or increased health care seeking is another matter," Weinberger tweeted in response to a question from Science.
Africa CDC is working with countries to make sure samples sent to national surveillance sites that test negative for influenza or other known respiratory illness are screened for COVID-19 as well, Nkengasong says. "That may help provide further clarity on the question of possible undetected cases."
We really have no idea how COVID-19 will behave in Africa.
Sub-Saharan Africa has one major advantage when it comes to COVID-19: Its average age is the lowest in the world. (The median age is less than 20.) Children rarely get sick from COVID-19, and most young adults appear to suffer mild symptoms; older people have a significantly higher risk of severe disease and death. Only 3% of sub-Saharan Africa's population is older than 65, compared with about 12% in China.
Some scientists also think the high temperatures in many African countries may make life harder for the virus that causes COVID-19, severe acute respiratory syndrome coronavirus 2. Grey thinks that's plausible; South Africa's flu season only starts in April when it gets colder. But whether COVID-19 will turn out to be a seasonal disease is still very much an open question.
Many other factors could make the pandemic worse in Africa. It will be hard to apply the interventions that have beaten back the virus to very low levels in China and have helped South Korea keep the epidemic more or less in check. Several countries have already introduced rules to thwart spread; Rwanda announced it would close places of worship, schools, and universities after its first case. But social distancing may be impossible in crowded townships, and it's not clear how confinement would work in African households where many generations live together, Ntoumi says. How do you protect the elderly, how can you tell village populations to wash their hands when there is no water, or use gel to sanitize their hands when they don't have enough money for food? "I'm afraid it will be chaos," she says.
And many African countries simply don't have the health care capacity to look after severely ill COVID-19 patients. A 2015 paper found that Kenya, a nation of 50 million people that declared its first case a few days ago, only had 130 intensive care unit beds and only about 200 specialized intensive care nurses. Many other countries face similar constraints, says Ifedayo Adetifa, a clinical epidemiologist at the KEMRI-Wellcome Trust Research Programme: "Broad-based population pyramid or not, with no universal health care and no health insurance, we simply can't afford to have many COVID-19 cases because we can't manage the most severe cases."
The high rates of other diseases could further complicate matters. "The most important thing for us is to describe the natural history of COVID-19 in South Africa to see if TB and HIV makes it worse," Gray says. Chances are that it will, based on experience with other respiratory infections. Last week, the Academy of Sciences of South Africa warned that people living with HIV are eight times more likely to be hospitalized for pneumonia caused by the influenza virus than the general population, and are three times more likely to die from it.
If cases continue to increase in South Africa, its scientists stand ready to study potential therapies. The country has a wealth of expertise and infrastructure for running randomized placebo-controlled trials (RCTs), for instance of HIV and TB drugs and vaccines. "What we're doing is trying to quickly identify sites so that, if this thing takes off, the big hospitals that have the capacity to do RCTs are ready to participate in treatment research," says Helen Rees, executive director of the Wits Reproductive Health and HIV Institute at the University of the Witwatersrand. Other research priorities for the country include finding ways to keep mild cases out of hospitals-to prevent the health system from becoming overwhelmed-and finding the best ways to prevent health care workers and other at-risk groups from becoming infected, Rees adds.
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