Invasive pneumococcal disease after implementation of a reduced three-dose pneumococcal conjugate vaccine program: a pediatric tertiary care center experience

Abstract

Following the implementation of a government-sponsored reduced three-dose (2 + 1) heptavalent conjugate pneumococcal vaccine (PCV7) program, we report a 61.4% decrease in the number of cases of invasive pneumococcal diseases (IPD) treated at our institution. Four years after the implementation of the three-dose reduced vaccine program, only 7.4% of IPD were caused by PCV7 serotypes, and there was an increase in the proportion of IPD caused by nonPCV7 serotypes; serotype 19A represented 40.7% of the strains isolated during the last year of the study. These results, similar to those previously observed with a regular four-dose (3 + 1) PCV7 schedule, are reassuring as to the effectiveness of a reduced three-dose (2 + 1) PCV7 program. Increasing numbers of IPD caused by nonPCV7 serotypes warrant the use of a new conjugate pneumococcal vaccine that contains serotype 19A.