China says the illness is not Sars (severe acute respiratory syndrome), nor Mers (Middle East respiratory syndrome), both of which are caused by coronaviruses, and so far it appears milder than both. Unlike Sars, it does not appear to spread easily between humans and unlike Mers, which has a mortality rate of about 35%, nobody has died. But the identification in preliminary laboratory tests by the Chinese of a novel coronavirus emerging once more from animals to infect humans is worrying for global health experts. When Sars appeared in China in 2002, it was not swiftly identified and contained. It spread around the world – particularly to Canada – via travellers.
Jeremy Farrar, director of Wellcome and an expert in tropical diseases, said: “Epidemics of diseases known and unknown are one of our greatest global health threats – threats that are with us constantly.