Geographic Variation in Invasive Pneumococcal Disease Following Pneumococcal Conjugate Vaccine Introduction in the United States

Background. Rates of invasive pneumococcal disease (IPD) varied among the United States before pneumococcal conjugate vaccine (PCV7) introduction. We compared trends in IPD rates among diverse US sites over 10 years since PCV7 introduction. Methods. Patients with IPD of all ages were identified through active population and laboratory-based surveillance in 8 geographic areas under continuous surveillance during 1998—2009. Isolates were serotyped. IPD incidence rates and percent changes were calculated by site, serotype group, age, and year. Results. Reductions in rates of IPD ranged, by site, from 19 to 29.9 cases per 100,000 population during 1998—1999 to 11.2—18.0 cases per 100,000 population during 2009 (rate reduction, 5.1—15.3 cases per 100,000 population). Reductions in IPD rates among children aged