Nasopharyngeal carriage and transmission of Streptococcus pneumoniae in American Indian households after a decade of pneumococcal conjugate vaccine use

Young children played a major role in pneumococcal nasopharyngeal carriage, acquisition, and transmission in the era before pneumococcal conjugate vaccine (PCV) use. Few studies document pneumococcal household dynamics in the routine-PCV7 era. We investigated age-specific acquisition, household introduction, carriage clearance, and intra-household transmission in a prospective, longitudinal, observational cohort study of pneumococcal nasopharyngeal carriage in 300 American Indian households comprising 1,072 participants between March 2006 and March 2008. Pneumococcal acquisition rates were 2-6 times higher in children than adults. More household introductions of new pneumococcal strains were attributable to children