PR5I, a hexavalent pediatric combination vaccine is being developed to reduce the number of injections during the first 2 years of life while providing a complete course of immunization against infection caused by H. influenzae type b, hepatitis B virus, Corynebacterium diphtheriae, Clostridium tetani, Bordetella pertussis, and poliovirus types 1, 2, and 3.