The scientific community believes that diseases that have long plagued the world can be controlled by vaccination. But vaccines won’t work unless they reach the people who need them most — and that means mostly people in poor countries. In two articles in the Journal of the American Medical Association, Harvard School of Public Health Dean Barry Bloom addresses this problem. Bloom and his colleagues describe the most promising approaches to vaccine development and encourage an international effort for testing and distribution. “AIDS, TB, and malaria are more severe problems in poor countries than in affluent ones, and these diseases have not received an investment in research dollars commensurate with their importance,” write Bloom and colleagues Norman Letvin and Stephen Hoffman.