CDC Africa and WHO officials say that the warnings were important. Very little was, and still is, known about Covid-19 and nations needed to urgently prepare. But nearly five months on, across Africa, those catastrophic scenarios just haven’t happened. Why it didn’t happen, and whether the worst still could happen, is one of the most consequential public health questions facing officials on the continent at this stage of the pandemic. A group of leading African scientists now believe that socio-ecological factors, the complex way that humans and their environment interact, could be playing an important role. The team bases that assessment on disease modelling published in late May in the open source journal BMJ Global Health. Their modeling assumes no significant health measures by governments and plugs in the known characteristics of the SARS-CoV-2 virus and multiple factors known to affect respiratory viral transmission. One key factors, say the authors, is the relative population movements across the continent. With sparse road networks and largely rural populations in some regions, the virus may have fewer opportunities to travel. Climactic factors, like weather and precipitation, also can impact the viral spread, according to the modelling.