Professor Paul Hunter from the University of East Anglia notes that almost every child contracts HMPV by five years of age, with reinfections occurring throughout life. “HMPV typically causes cold-like symptoms that recover by themselves within 2 to 5 days. Severe cases are rare but can occur in vulnerable groups,” he says.

The pictures emerging are arresting: a hospital waiting room in Beijing, full of masked patients apparently attached to drips; crowds of mask-wearing commuters making their way through the city. If it all seems unnervingly familiar,

So what is the real situation and what is HMPV anyway? HMPV is a respiratory virus in the same family as the more commonly known respiratory syncytial virus (RSV). It is not a new infection and has probably been circulating in humans for centuries.