Less than five months after the first documented case of the Covid-19 coronavirus, infections exceed ^[1] 500,000 globally, with nearly 24,000 deaths. This pandemic is devastating societies and economies all over the world, but Africa stands to face particularly severe and long-lasting damage.

To be sure, Africa isn’t suffering as much as many expected—at least not so far. Though the number of affected countries on the continent has risen to 39 ^[2], the virus doesn’t seem to be spreading as rapidly as it has elsewhere.

Some scientists think ^[3] this could be partly a matter of climate. One study ^[4] found that the Covid-19 virus may be less stable at higher temperatures, with the optimal temperature for transmission probably hovering at around 8.72°C. Temperatures in most African countries rarely drop below 15°C. This doesn’t mean that the Covid-19 virus can’t be transmitted in hotter climates, only that it may be easier to contain there.

But other serious challenges to containment remain—beginning with the fact that Covid-19 has a longer incubation time ^[5] than the common cold (another coronavirus), and asymptomatic individuals are contagious. While symptomatic people are more contagious ^[6], and this seems to be the primary mechanism for the virus’s spread, asymptomatic people pose a significant danger, because they are less likely to limit their interactions. This makes transmission much harder to track.

Then there’s the issue of severity. While most Covid-19 cases are characterised by only mild to moderate symptoms, the virus’s severity rises sharply for the elderly ^[7] and those with underlying health conditions ^[8], including cardiopulmonary disease and diabetes.

As the world’s youngest continent, with a median age ^[9] of 18 (less than half the median age of Europe), Africa may have less to worry about in terms of severity. It’s no coincidence that, based on numbers of confirmed cases and deaths, the mortality rate ^[10] in Italy—with a median age of 47.3—has reached 9.2% ^[11], compared with a global average ^[12] of around 3.4%.

In terms of underlying health conditions, however, Africa is on a much weaker footing. Though non-communicable diseases like diabetes have traditionally been associated with developed countries, there is evidence ^[13] that they are proliferating in Africa. Moreover, Africa is beset by two other conditions—HIV and tuberculosis—which could pose serious risks to those infected with Covid-19.

Sub-Saharan Africa is home ^[14] to about 70% of people living with HIV globally, and 25% of the world’s new TB cases—the leading cause of death among HIV-infected people—occur in Africa. Because HIV and TB are not widespread in the regions hardest hit by the coronavirus so far, there’s little data about their implications for those infected with Covid-19. But it does seem fair to assume that people with HIV and/or TB are at a higher risk of developing more severe forms of Covid-19.

There may be some reason for hope: some countries are evaluating the effectiveness of certain anti-retroviral ^[15] drugs on Covid-19. If they work, it would be a huge relief for Africans. More than 60% of HIV-positive people ^[16] in southern and eastern Africa—the regions most affected by HIV—are already on anti-retroviral treatment.

But encouraging results are far from guaranteed. And even if they were, nearly 40% of the HIV-positive population in southern and eastern Africa—20.6 million people, in total—would still be highly vulnerable.

A final major risk for Africa during the Covid-19 pandemic lies in the weakness of healthcare systems. If the virus has been able to overwhelm a modern health system in a developed country like Italy, there is no telling what would happen in an African country with a health system that is already weak and under-resourced.

As the rapid global spread of Covid-19 makes clear, this is not just a problem for Africa. If the virus gains a foothold on the continent, it could spill back to the rest of the world, creating new outbreaks in countries that had brought it under control. The only solution is for external actors to work with African governments to address key weaknesses—before it’s too late.