How do you contain a global epidemic such as coronavirus?

“MADE IN CHINA” is a label the country’s government would prefer to be associated with slick technology. Its trending export at present, however, is 2019-nCoV, the new coronavirus that struck in the Chinese city of Wuhan in December. The virus has now spread to at least 16 countries. As The Economist went to press, the World Health Organisation (WHO) and China had confirmed almost 7,800 infections and 170 deaths, almost all in China.

When a new infectious disease begins to spread, decisions on how to stop it are based on patchy data that change by the hour. This is “the fog of war” phase, says David Heymann of the London School of Hygiene and Tropical Medicine. Health officials have to make decisions quickly and with uncertain information, says Jeremy Farrar of the Wellcome Trust, a charity.