As Yogi Berra (or Niels Bohr or Samuel Goldwyn) is supposed to have said, it’s difficult to make predictions, especially about the future. It’s especially dangerous to try to predict the behavior of infectious diseases, when small unpredictabilities in climate or trade or the behavior of governments can bring a problem that we thought was handled roaring back to life.

But as 2016 opens, it is fair to say that the disease public health experts are pinning their hopes on, the one that might truly be handled this year, is polio. There were fewer cases last year than ever in history: 70 wild-type cases, and 26 cases caused by mutation in the weakened virus that makes up one of the vaccines,