Predicting Covid-19 Hotspots
Researchers understand reasonably well that the disease spreads in places where people spend a lot of time face-to-face, such as care homes, hospitals and restaurants. Duration of contact, physical proximity and environmental conditions are the main factors. A fleeting encounter with a passer-by on a path is less likely to result in infection than sitting inside next to a person for 20 minutes. Cramped and poorly ventilated indoor spaces are riskier than expansive outdoor ones.
But many more factors have a role, and these are less understood. Some people do not com- ply with safety measures, for many reasons. Inebriated diners and excitable theme-park visitors, for example, are unlikely to stay metres apart. The degree of mixing differs. The same group of students might sit together in a classroom every day. But children in secondary school mingle with more students and teach- ers than do those in preschools. And school- children meet widely outside school hours, when commuting, playing sports or attending tutorials (see ‘School networks’).
