Epidemiology of Invasive Pneumococcal Disease among Adult Patients in Barcelona Before and After Pediatric 7-Valent Pneumococcal Conjugate Vaccine Introduction, 1997–2007

Background. A dramatic decrease in the incidence of invasive pneumococcal disease (IPD) was observed among children and adults in the United States after the introduction of the 7-valent pneumococcal conjugate vaccine (PCV7). Little is known about the incidence of IPD after PCV7 licensure in Europe. The objective of this study was to examine changes in the prevalence of IPD among adults in the PCV7 era. Methods. We undertook a prospective study involving adults with IPD who required hospital admission in the southern area of Barcelona, Spain. Three periods were studied: the pre-PCV7 period (1997–2001), the early PCV7 period (2002–2004), and the late PCV7 period (2005–2007). Results. A total of 1007 episodes of IPD were observed. Rates of IPD among adults increased from 13.9 to 14.6 episodes per 100,000 population between the pre-PCV7 period and the early PCV7 period (P=.6) and then to 19.55 episodes per 100,000 population in the late PCV7 period (P