I read an article in the late 1990s about a diarrheal disease that was claiming the lives of hundreds of thousands of children each year, and I couldn’t believe that something I’d never even heard of was killing so many. Rotavirus doesn’t get much press, because it’s almost never deadly in wealthy countries. But it was a catalyst for my commitment to global health — in fact, one of our foundation’s first grants supported treatment efforts to combat the illness. Since then, a cheap and effective vaccine has cut the number of children’s deaths nearly in half, and the vaccine is reaching more kids than ever before. In India, where rota kills nearly 80,000 children a year, the government decided this year to deliver the vaccine for free to poor children. And manufacturers there are working on a more affordable vaccine that could reach even more children in the coming years.