Like Watson, Hombach is concerned that lessons are learnt from past mistakes and says that the most obvious way of doing this is to avoid confusion and wasteful false starts. “It’s a major commitment for countries to introduce the vaccine,” Hombach says. “And once you’re in, you’re in. You can’t have it one year, then drop it the next.” Nor is Hombach entirely convinced that dengue will be the next big push. “It is unclear