Effect of reduced-dose schedules with 7-valent pneumococcal conjugate vaccine on nasopharyngeal pneumococcal carriage in children: a randomized controlled trial.

<bold>Context: </bold>The effects of reduced-dose schedules of 7-valent pneumococcal conjugate vaccine (PCV-7) on pneumococcal carriage in children are largely unknown, although highly relevant in the context of subsequent herd effects.<bold>Objective: </bold>To examine the effects of a 2-dose and 2 + 1-dose PCV-7 schedule on nasopharyngeal pneumococcal carriage in young children compared with controls.<bold>Design, Setting, and Patients: </bold>A randomized controlled trial of nasopharyngeal carriage of Streptococcus pneumoniae enrolling 1003 healthy newborns and 1 of their parents in a general community in The Netherlands, with follow-up to age 24 months and conducted between July 7, 2005, and February 14, 2008.<bold>Intervention: </bold>Infants were randomly assigned to receive 2 doses of PCV-7 at 2 and 4 months; 2 + 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (control group).<bold>Main Outcome Measure: </bold>Vaccine serotype pneumococcal carriage rates in infants in the second year of life.<bold>Results: </bold>At 12 months, vaccine serotype pneumococcal carriage was significantly decreased after both PCV-7 schedules, with vaccine serotype pneumococcal carriage rates of 25% (95% confidence interval [CI], 20%-30%) and 20% (95% CI, 16%-25%) in the 2-dose and 2 + 1-dose schedule groups, respectively, vs 38% (95% CI, 33%-44%) in the control group (both P < .001). At 18 months, in the 2 + 1-dose schedule group, vaccine serotype pneumococcal carriage had further decreased to 16% (95% CI, 12%-20%) and, at 24 months, to 14% (95% CI, 11%-18%; both P < .001); whereas in the 2-dose schedule group, vaccine serotype pneumococcal carriage had remained stable at 18 months (24%; 95% CI, 20%-29%), but at 24 months had further decreased to 15% (95% CI, 11%-19%; both P < .001). In the control group, vaccine serotype pneumococcal carriage remained around 36% to 38% until 24 months.<bold>Conclusion: </bold>Compared with no pneumococcal vaccination, a 2 + 1-dose and 2-dose schedule of PCV-7 resulted in significant reductions of vaccine serotype pneumococcal carriage in the second year of life.<bold>Trial Registration: </bold>clinicaltrials.gov Identifier: NCT00189020. [ABSTRACT FROM AUTHOR]