Every so often, our vague awareness of our vulnerability as a species crystallises around a specific threat. At first, we note with unconcern a handful of cases of a new illness, somewhere far away. Soon it begins to spread. The deaths mount. We start to wonder whether we are being complacent rather than sensible, and whether we are living through the early montage in a disaster movie, in which families bicker over breakfast as news reports on the killer virus play unnoticed in the background. Could this be a new pandemic which will sweep the globe killing tens of millions, as Spanish flu once did?

The story of the new coronavirus, first reported in Wuhan, China, last month, now seems to be reaching the point where public indifference tips into worry and even fear. It causes pneumonia; Beijing says six people have died and 300 have been infected as it has spread. On Monday, officials confirmed that there was human-to-human transmission. Sales of face masks have soared. Cases have been reported in Thailand, Japan, the Philippines and elsewhere, though all confirmed incidents involve patients who had been in China. On Wednesday, the World Health Organization will hold an emergency meeting.