The killer came from the east in winter: fever, cough, sore throat, aching muscles, headache and sometimes death. It spread quickly to all parts of the globe, from city to city, using new transport networks. In many cities, the streets were empty and shops and schools deserted. A million died. The Russian influenza pandemic of 1889-90 may hold clues to what happens next — not least because the latest thinking is that it, too, may have been caused by a new coronavirus.
In addition to the new diseases of Sars, Mers and Covid-19, there are four other coronaviruses that infect people. They all cause common colds and are responsible for about one in five such sniffles, the rest being rhinoviruses and adenoviruses. As far as we can tell from their genes, two of these coronaviruses came from African bats (one of them bizarrely via alpacas or camels), and two from Asian rodents, one of them via cattle.
This last one, known as OC43, is the commonest of the cold coronaviruses. It comes around every winter and apparently sometimes reinfects people who have had it before. Unlike the other three, its origin is not lost in the mists of time but is known to be comparatively recent. Comparing its genetic sequence with that of its close bovine cousin, Dr Marc van Ranst at Leuven University in Belgium and his colleagues calculated in 2005 that they shared a common ancestor around the year 1890. (There is also a version of the same virus that infects pigs but it is slightly less close to the human and cattle versions than they are to each other.) That date was therefore probably when the virus jumped into the human species for the first time.
The date is intriguing because 1889-90, as previously stated, saw a terrible pandemic, the worst of the 19th century, caused by a respiratory infection.