Postlicensure evaluation of the effectiveness of seven valent pneumococcal conjugate vaccine.

To evaluate the impact of the introduction and routine use of seven valent pneumococcal conjugate vaccine on the epidemiology of invasive pneumococcal disease within the Northern California Kaiser Permanente (KP) population. Surveillance for invasive pneumococcal disease has been in place within KP since 1995. Isolates from normally sterile sites in children are routinely sent for serotyping. Cases of invasive disease are identified through review of automated microbiology records within KP. Incidence rates of invasive disease were compared for the period before and after routine use of pneumococcal conjugate vaccine in children. The incidence of invasive pneumococcal disease caused by vaccine serotypes before the licensure and routine use of pneumococcal conjugate vaccine ranged between 51.52 and 98.15 cases per 100 000 person years in children <1 year of age and fell to 9.35 after introduction of vaccine. The incidence in children <2 years of age was 81.67 to 113.80 before introduction and 38.22 cases per 100 000 person years after introduction of the vaccine into the general population. These reductions in disease rates exceeded the average vaccine coverage substantially in each age group. No increase in disease incidence was observed for possibly cross-reacting serotypes or nonvaccine serotypes. The introduction and routine use of pneumococcal conjugate vaccine in our population have been associated with a substantial reduction in invasive disease incidence in children <5 years of age.