Combination vaccines

The replacement of multiple individual vaccines with one or more combination vaccines can simplify vaccine administration programs and permit the inclusion of new antigens in the vaccine schedule. Although the development, evaluation, and implementation of combination vaccines pose numerous challenges and raise controversies that remain unresolved, there is a reasonable prospect of US licensure within the next few years of one or two pentavalent combination vaccines for infant use. Enhanced vaccination tracking systems and postmarking efficacy surveillance should provide confidence that material reductions in efficacy could be detected following Licensure, and thereby ease the approval of combinations that result in moderate, but perhaps immaterial, declines in immunogenicity.