Lawrence Corey, professor at the University of Washington School of Medicine, discusses how vaccines work to influence population-based effects on reducing and infection or disease. Dr. Corey describes the financial and scientific challenges in developing vaccines for diseases that affect primarily the non-industrialized countries and discusses why developing and manufacturing new types of vaccines has lagged behind the development of novel therapies. His presentation also focuses on issues surrounding the HIV vaccine and pandemic avian flu. From the Series:2006 Pediatric Bioethics Conference: Ethical Issues Related to Vaccination of Children