Incidence of Invasive Pneumococcal Disease in Children 3 to 36 Months of Age at a Tertiary Care Pediatric Center 2 Years After Licensure of the Pneumococcal Conjugate Vaccine

A dramatic decline in the incidence of invasive disease caused by Streptococcus pneumoniae among healthy infants is anticipated to result from universal immunization with the heptavalent pneumococcal conjugate vaccine (PCV7). To assess change in the incidence of invasive pneumococcal disease among young children between the fiscal years of 1997 and 2002 at the Children's Hospital of Pittsburgh, a retrospective review of medical records was performed. Information regarding demographics, receipt of pneumococcal vaccine, medical history, and events of the acute illness were reviewed among patients 3 to 36 months of age with a positive blood or cerebrospinal fluid culture. Penicillin susceptibility data were obtained and capsular serotyping was performed on available isolates. The incidence of invasive pneumococcal disease decreased significantly in the 2001 and 2002 fiscal years compared with previous years. This occurred predominantly in children 3 to 24 months of age. Boys were overrepresented among cases of invasive disease. The incidence of invasive disease among children of African American descent was significantly greater than expected based on local demographics. The dramatic decline in invasive pneumococcal disease in the context of increasing emergency department visits and a stable pattern of clinical practice almost certainly reflects the impact of the initial use of the PCV7. The availability and continued use of PCV7 should lead to even more impressive changes in the epidemiology of pneumococcal infection.