The first Precision Vaccines Program joint international team effort is the Expanded Program on Immunization Consortium (EPIC). This pilot study is ongoing with strong collaboration from Drs. Hancock, Kampmann, Kollmann, Ozonoff, Pomat, Steen, Tebbutt, van den Biggelaar, van Haren, and many others. Infection is the most common cause of death in early life, especially for newborns and can be reduced by immunization but insufficient knowledge of how vaccines protect the very young limits their optimal use. This pilot study, with two clinical sites in The Gambia and Papua New Guinea, aims to understand the impact of early life immunization. We hope characterizing vaccine-induced molecular patterns (“signatures”) that correspond to vaccine-mediated protection will accelerate development and optimization of vaccines against early life infections of major global health importance.