Nine years ago, a small group of infectious-disease experts gambled on an unorthodox strategy to make a much-needed—and affordable—vaccine for Africa. Last Monday in Burkina Faso, it paid off in spades with the kickoff of a massive campaign to immunize 20 million people in three African countries against deadly meningococcal meningitis by the end of December.

Crippling epidemics of meningococcal meningitis sweep across Africa with the onset of the dry season and harsh harmattan winds. An affordable, effective vaccine in the works could change that.