IF only somebody had counted the orphans. That was one wish I had while trawling archives on the 1918 influenza pandemic to research my book Pale Rider. Another yearning? If only someone had saved biological samples of the unidentified respiratory disease that ravaged China in late 1917. Historians a century hence will, I think, have a lot more to go on…

This article first appeared in Nature on 17 December 2020. To continue reading, click here.