Do you remember the H1N1 swine flu that made tens of millions sick and killed thousands of people in 2009? Well, one if its cousins, a bird flu with the name H7N9, is causing some death and consternation in China. This strain has long been circulating among birds, but since earlier this year people have become ill with this respiratory virus, all so far in China. This week’s issue of the New England Journal of Medicine (NEJM...