The Pediatric Infectious Disease Journal •  Volume 31, Number 9, September 2012 www.pidj.com | e169 ORIGINAL STUDIES Background: The seven-valent pneumococcal conjugate vaccine (PCV7) was licensed in Canada in 2001. Routine infant vaccination programs in Alberta began in 2002. Several years after PCV7 introduction, the routine use of PCV7 in infants and high-risk children has led to near elimination of invasive pneumococcal disease (IPD) caused by vaccine serotypes. Methods: Prospective, population-based surveillance of all IPD cases was conducted from January 1998 to December 2010. Demographic, clinical and microbiologic data were collected. Results: There were 1462 IPD cases over 13 years. Comparing PCV7 sero- type IPD incidence in the prevaccine period (1998–2001) to the late post- vaccine period (2007–2010), there were declines in children 0–5 months (100%), 6–23 months (98%), 2–4 years (97%), 5–15 years (100%) as well as in adults 16–64 years (73%), 65–84 years (90%) and ≥85 years of age (100%). From 2008 to 2010, there were no cases of PCV7 serotype IPD in children under 2 years of age. There have been increases in non-PCV7 serotype IPD; notably, serotypes 5 and 19A have increased significantly in adults and 19A in children. Conclusions: PCV7 serotype IPD has been eliminated in vaccine-eligible young children and nearly eliminated in all other age groups. Serotype 19A increased significantly at all ages before the introduction of an expanded valency pneumococcal conjugate vaccine. Key Words: Streptococcus pneumoniae, 7-valent pneumococcal vaccine, epidemiology, invasive pneumococcal disease, Alberta, Canada (Pediatr Infect Dis J 2012;31: e169–e175) S treptococcus pneumoniae frequently colonizes the human naso- pharynx. 1–4 It is a major etiologic agent of sinusitis, otitis media and community-acquired pneumonia, which result from direct spread from the nasopharynx, and invasive infections like septice- mia, meningitis and bacteremic pneumonia. 1,5 Invasive pneumococ- cal disease (IPD) most frequently affects children less than 2 years of age, adults at least 65 years of age and immune-compromised individuals. 6–8 The 7-valent pneumococcal conjugate vaccine (PCV7 [Prevnar, Pfizer Canada Inc., Kirkland, Quebec, Canada]) was licensed in Canada in 2001. In 2002, Alberta became the first prov- ince in Canada to introduce routine infant immunization programs. The 7 serotypes (4, 6B, 9V, 18C, 19F, 23F) targeted by PCV7 were responsible for more than 80% of IPD in children in North America before the vaccine’s development and implementation. 1,7,8 Several studies have described the direct effect of PCV7 in vaccine recipi- ents as well as the indirect herd effect to prevent disease in unvac- cinated children and adults. 8–13 Concomitant with the decrease in incidence of IPD by the PCV7 vaccine serotypes, there has been an increase in the incidence of IPD caused by nonvaccine serotypes. 7–9 The potential for vaccination to contribute to the emergence of serotypes not included in the vaccine is of concern, because it is not known whether these serotypes result in more severe disease than the PCV7 serotypes. 14–16 The Calgary Area Streptococcus pneumoniae Epidemiology Research group began prospective population-based surveillance of IPD among persons of all ages in the Calgary Zone on January 1, 1998 that continues to the present time. This surveillance program has the longest PCV7 vaccine follow-up experience within Canada, given the early introduction of PCV7 in Alberta. To our knowledge, we were among the first to report the effectiveness of PCV7 in chil- dren and adults outside of the United States. 9,17 This study further describes the impact of PCV7 on vaccine serotype IPD at all ages in our population, nearly a decade after the introduction of PCV7. MATERIALS AND METHODS Study Design The Calgary Area Streptococcus pneumoniae Epidemiology Research group began prospective, population-based longitudinal surveillance study of IPD among persons of all ages in the Calgary Zone (formerly, Calgary Health Region) on January 1, 1998. Cases observed up to December 31, 2010 are reported here. Setting The Calgary Zone includes the city of Calgary and several surrounding communities in the province of Alberta, Canada. The study population included all persons whose home address postal code was within the boundaries served by the Calgary Zone. The Calgary Zone boundaries remained the same as the former Calgary Health Region following the reorganization of health services in Alberta. The population of the Calgary Zone increased 53% through overall growth from 888,432 in 1998 to 1,362,976 persons in 2010 (Health Systems Analysis Unit, Data Integration, Measurement & Reporting Program, Alberta Health Services, Calgary, Alberta). Case Definition A case of IPD was defined as an individual with an acute illness who had S. pneumoniae isolated from a normally sterile Copyright © 2012 by Lippincott Williams & Wilkins ISSN: 0891-3668/12/3109-e169 DOI: 10.1097/INF.0b013e3182624a40 Eradication of Invasive Pneumococcal Disease due to the Seven-valent Pneumococcal Conjugate Vaccine  Serotypes in Calgary, Alberta Jenine Leal, MSc,* Otto G. Vanderkooi, MD,*†‡¶ Deirdre L. Church, MD, PhD,‡§¶ Judy MacDonald, MD,||** Gregory J. Tyrrell, PhD,††‡‡ and James D. Kellner, MD*†** Accepted for publication, May 31, 2012. From the *Departments of Pediatrics, †Microbiology, Immunology and Infectious Diseases, and ‡Pathology and Laboratory Medicine, University of Calgary; §Department of Medicine, University of Calgary; ¶Calgary Laboratory Services; ǁPopulation and Public Health, Alberta Health Services; **Department of Community Health Sciences, University of Calgary, Calgary; ††National Centre for Streptococcus, Edmonton; and the ‡‡Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada. OGV, JM and JDK are supported by an Investigator Initiated Research Grant from Pfizer Canada Inc. The authors have no other funding or conflicts of interest to disclose. Address for Correspondence: Otto G. Vanderkooi, MD, Division of Infectious Diseases, Alberta Children’s Hospital, 2888 Shaganappi Trail NW Calgary, AB T3B 6A8, Canada. E-mail: ovanderk@ucalgary.ca.