One year ago Monday, scientists confirmed that the cause of a deadly fever in Guinea, which had already killed 59 people and was continuing to spread, was the Ebola virus. Twelve months later, trials for a second promising vaccine have begun in Guinea, with a first trial already underway in Liberia. But this progress doesn’t mean that the Ebola crisis has been solved or that we’re better prepared for future epidemics yet.

The best news is that the epidemic is coming under control. In the week to March 8, 116 new cases were...