With sars-cov-2 now spread around the world, the aim of public-health policy, whether at the city, national or global scale, is to flatten the curve, spreading the infections out over time.
This has two benefits. First, it is easier for health-care systems to deal with the disease if the people infected do not all turn up at the same time. Better treatment means fewer deaths; more time allows treatments to be improved. Second, the total number of infections throughout the course of the epidemic can be lower.
To flatten the curve you must slow the spread. The virus appears to be transmitted primarily through virus-filled droplets that infected people cough or sneeze into the air. This means transmission can be reduced through physical barriers, good hygiene and reducing various forms of mingle—a strategy known as “social distancing”. Such measures are already routinely used to control the spread of the influenza virus, which spreads in a similar way and is responsible for hundreds of thousands of deaths a year.
Influenza, like many other respiratory diseases, thrives in cold and humid air. If covid-19 behaves the same way, spreading less as the weather gets warmer and drier, flattening the curve will bring an extra benefit. As winter turns to spring then summer, the reproductive rate will drop of its own accord. Dragging out the early stage of the pandemic means fewer deaths before the summer hiatus provides time to stockpile treatments and develop new drugs and vaccines—efforts towards both of which are already under way.
Ben Cowling, an epidemiologist at the University of Hong Kong, says that the intensity of the measures countries employ to flatten the curve will depend on how deadly sars-cov-2 turns out to be. It is already clear that, for the majority of people who get sick, covid-19 is not too bad, especially among the young: a cough and a fever. In older people and those with chronic health problems such as heart disease or diabetes, the infection risks becoming severe and sometimes fatal. How often it will do so, though, is not known.
