Panic spreads faster than a pandemic. That might not make it irrational. Signs that the coronavirus is going global sent share prices plummeting this week. But equity valuations are stretched — the Stoxx Europe 600 reached a record high last week. Further falls are on the cards if, as seems likely, the outbreak worsens.

True, there are risks in joining the stampede. Legendary investor Warren Buffett this week described the outbreak as “scary stuff” but cautioned against selling on the headlines. The Sars outbreak of 2002-03 showed that prices can bounce back sharply once an infection subsides.

But already Covid-19 has infected 10 times as many people as Sars did and killed more than three times as many people. China is a far bigger part of global production and consumption than was the case in 2003. The hit to global GDP will be even worse if Covid-19 is not confined to Asia.