Impact of Introduction of Conjugate Vaccines in the Vaccination Schedule on the Incidence of Pediatric Invasive Pneumococcal Disease Requiring Hospitalization in Madrid 2007 to 2011

Differences in invasive pneumococcal disease (IPD) in children are expected after a change from 7-valent pneumococcal conjugate vaccine (PCV7) to 13-valent pneumococcal conjugate vaccine (PCV13). Universal vaccination with PCV7 started in Madrid in November 2006, and it switched to PCV13 in June 2010. A prospective, laboratory-confirmed (by culture or polymerase chain reaction), clinical surveillance including all pediatric IPD requiring hospitalization in Madrid was performed in all hospitals with a pediatric department and included four 1-year periods from May 2007 to April 2011. Incidence rate (IR) was calculated as number cases per 100,000 inhabitants using children population data. Six hundred fourteen IPDs were identified: 209 parapneumonic pneumococcal empyema, 191 bacteremic pneumonia, 75 primary bacteremia, 72 meningitis, 38 IPDs secondary to otic foci and 29 others. The incidence of IPD remained unchanged during 2007-2010 (IR=≈17.0), with a marked decrease in 2010-2011 (IR=11.34; P