Vaccines are among the most efficacious and cost-effective human health interventions available. They provide protection against a surprisingly broad spectrum of infectious diseases. Notable recent successes protect against human papillomavirus (Cervarix and Gardasil vaccines from GlaxoSmithKline and Merck, respectively) and rotavirus (Rotarix and RotaTeq vaccines from GlaxoSmithKline and Merck, respectively). However, generating reliable sterilizing or therapeutic immunity is still not possible against a number of latent and chronic pathogens that especially affect people in developing countries. Among those…