The effect of an alternative reduced-dose infant schedule and a second year catch-up schedule with 7-valent pneumococcal conjugate vaccine on pneumococcal carriage: A randomized controlled trial

► The extent of PCV effect on carriage determines indirect protection. ► PCV7 is licensed as a 4-dose regimen (3 + 1), but shorter regimens are often adopted. ► We show that a reduced schedule (2 + 1) results in nasopharyngeal carriage reduction. ► 3 + 1 and 2 + 1 schedules showed differences in PCV7-type carriage corrected by booster. ► We found that 2-dose 2nd-year catch-up campaigns may enhance carriage reduction.