title: The changing epidemiology of invasive pneumococcal disease at a tertiary children's hospital through the 7-valent pneumococcal conjugate vaccine era: a case for continuous surveillance.
abstract: BACKGROUND
  In 2000, a 7-valent pneumococcal conjugate vaccine (PCV7) was licensed for use among US children. Many sites have since reported changes in invasive pneumococcal disease (IPD). We recognized an opportunity to describe the changes in epidemiology, clinical syndromes, and serotype distribution during a 14-year period including 4 years before vaccine introduction and spanning the entire PCV7 era.
  
  
  METHODS
  Cases were defined as children <18 years of age who were cared for at Primary Children's Medical Center for culture-confirmed IPD. We defined the prevaccine period as the time frame spanning from 1997 to 2000 and the postvaccine period from 2001 to 2010. Demographics, clinical data, and outcomes were collected through electronic query and chart review. Streptococcus pneumoniae serotyping was performed using the capsular swelling method.
  
  
  RESULTS
  The median age of children with IPD increased from 19 months during the prevaccine period to 27 months during postvaccine period (P = 0.02), with a larger proportion of IPD among children older than 5 years. The proportion of IPD associated with pneumonia increased substantially from 29% to 50% (P < 0.001). This increase was primarily attributable to an increase in complicated pneumonia (17% to 33%, P < 0.001). Nonvaccine serotypes 7F, 19A, 22F, and 3 emerged as the dominant serotypes in the postvaccine period. In children with IPD who were younger than 5 years, for whom vaccine is recommended, 67% of the cases were caused by serotypes in 13-valent PCV during 2005 to 2010.
  
  
  CONCLUSIONS
  After PCV7 was introduced, significant changes in IPD were noted. One-third of IPD occurred in children older than 5 years, who were outside the age-group for which PCV is recommended. Continued surveillance is warranted to identify further evolution of the epidemiology, clinical syndromes, and serotype distribution of S. pneumoniae after 13-valent PCV licensure.
authors.affiliation: Division of Pediatric Infectious Diseases, Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City, UT 84108, USA. Krow.Ampofo@hsc.utah.edu
authors.forename: Krow
authors.initials: K
authors.lastname: Ampofo
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Pavia
authors.forename: Stockmann
authors.initials: S
authors.lastname: Chris
authors.forename: Adam L
authors.initials: AL
authors.lastname: Hersh
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Bender
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Blaschke
authors.forename: Hsin Yi Cindy
authors.initials: HY
authors.lastname: Weng
authors.forename: Kent E
authors.initials: KE
authors.lastname: Korgenski
authors.forename: Judy
authors.initials: J
authors.lastname: Daly
authors.forename: Edward O
authors.initials: EO
authors.lastname: Mason
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Byington
mesh_terms: D000293:Adolescent; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006761:Hospitals; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008586:Meningitis, Pneumococcal / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology; D010003:Osteoarthritis / Q000453:epidemiology / Q000382:microbiology / Q000473:pathology; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology / Q000473:pathology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*; D014481:United States / Q000453:epidemiology
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines