title: Invasive pneumococcal disease after implementation of 13-valent conjugate vaccine.
abstract: OBJECTIVE
  To examine whether there is a different clinical profile and severity of invasive pneumococcal disease (IPD) in children caused by nonvaccine types in the era of 13-valent pneumococcal conjugate vaccine (PCV13).
  
  
  METHODS
  Observational study of childhood IPD in Massachusetts based on state public health surveillance data comparing pre-PCV13 (2007-2009) and post-PCV13 (2010-2012) eras.
  
  
  RESULTS
  There were 168 pre-PCV13 cases of IPD and 85 post-PCV13 cases of IPD in Massachusetts children ≤5 years of age. PCV13 serotypes declined by 18% in the first 2 years after PCV13 use (P = .011). In the post-PCV13 phase, a higher proportion of children were hospitalized (57.6% vs. 50.6%), and a higher proportion of children had comorbidity (23.5% vs. 19.6%). Neither difference was statistically significant, nor were comparisons of IPD caused by vaccine and nonvaccine types. Children with comorbidities had higher rates of IPD caused by a nonvaccine type (27.6% vs. 17.2%; P = .085), were more likely to be hospitalized (80.4% vs. 50%; P < .0001), and were more likely to have a longer hospital stay (median of 3 days vs. 0.5 days; P = .0001).
  
  
  CONCLUSIONS
  Initial data suggest that nonvaccine serotypes are more common in children with underlying conditions, who have greater morbidity from disease. In the post-PCV13 era, a larger proportion of patients are hospitalized, but mortality rates are unchanged. Routine vaccination with PCV13 may not be enough to reduce the risk in patients with comorbidity.
authors.affiliation: University of Minnesota Children's Hospital, Minneapolis, Minnesota; irohtam@umn.edu.
authors.forename: Pui-Ying
authors.initials: PY
authors.lastname: Iroh Tam
authors.affiliation: Massachusetts Department of Public Health, Boston, Massachusetts;University of Massachusetts Medical School, Worcester, Massachusetts;
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Madoff
authors.affiliation: Clinical and Translational Science Institute, University of Minnesota, Minneapolis, Minnesota; and.
authors.forename: Brandon
authors.initials: B
authors.lastname: Coombes
authors.affiliation: Boston University Medical Center, Boston, Massachusetts.
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Pelton
mesh_terms: D002675:Child, Preschool; D015897:Comorbidity; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008297:Male; D008404:Massachusetts; D008826:Microbial Sensitivity Tests; D011008:Pneumococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology* / Q000517:prevention & control; D022242:Pneumococcal Vaccines; D012703:Serotyping; D012720:Severity of Illness Index; D013296:Streptococcus pneumoniae / Q000145:classification; D016896:Treatment Outcome; D018074:Vaccines, Conjugate
chemical_list: C538862:13-valent pneumococcal vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate
keywords: children; comorbidity; conjugate vaccine; invasive pneumococcal disease; severity