title: Differential impact of pneumococcal conjugate vaccines on bacteremic pneumonia versus other invasive pneumococcal disease.
abstract: BACKGROUND
  Bacteremic pneumonia (BP) accounts for ~35% of invasive pneumococcal disease (IPD) in young children. Our aims were to compare age, seasonal and serotype distribution of BP versus non-BP IPD and to determine whether the impact of the sequential 7/13-valent pneumococcal conjugate vaccine (PCV7/PCV13) introduction on disease incidence differed between BP and non-BP IPD in children <5 years of age.
  
  
  METHODS
  A nationwide, prospective, population-based, active surveillance (July 2004-June 2013) was conducted. All IPD episodes were included. PCV7 was introduced to the Israeli National Immunization Plan in July 2009 and has been replaced by PCV13 since November 2010.
  
  
  RESULTS
  In all, 983 (36.8%) BP and 1687 (63.2%) non-BP IPD episodes were recorded. A higher proportion of BP than that of non-BP IPD episodes (42.0% vs. 20.7%; P < 0.001) occurred in children >24 months old. Seasonality differed between BP and non-BP IPD, with yearly earlier peaks of non-BP IPD. The proportion of the 5 additional PCV13 serotypes (1, 3, 5, 7F and 19A) was higher in children with BP versus non-BP IPD (39.6% vs. 23.6%; P < 0.01). Shortly after PCV7 introduction, non-BP IPD rate was significantly reduced but that of BP was not. However, PCV13 introduction resulted in rapid reduction of BP rate, with a further reduction of non-BP IPD.
  
  
  CONCLUSIONS
  The differences in age distribution, seasonality and serotype distribution between BP and non-BP IPD suggest that the pathogenesis of these 2 entities is not identical and resulted in different impact rate dynamics after PCV7 and PCV13 introduction.
authors.affiliation: From the *Pediatric Infectious Disease Unit, Soroka University Medical Center, Ben-Gurion University, Beer Sheva, Israel; †Pediatric Infectious Disease Unit, Meir Medical Center, Kfar Saba, Israel; and ‡Pediatric Infectious Disease Unit, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors.forename: Shalom
authors.initials: S
authors.lastname: Ben-Shimol
authors.forename: David
authors.initials: D
authors.lastname: Greenberg
authors.forename: Guy
authors.initials: G
authors.lastname: Hazan
authors.forename: Noga
authors.initials: N
authors.lastname: Givon-Lavi
authors.forename: Giora
authors.initials: G
authors.lastname: Gottesman
authors.forename: Galia
authors.initials: G
authors.lastname: Grisaru-Soen
authors.forename: Ron
authors.initials: R
authors.lastname: Dagan
mesh_terms: D017677:Age Distribution; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D002675:Child, Preschool; D062665:Epidemiological Monitoring; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007557:Israel / Q000453:epidemiology; D008297:Male; D008586:Meningitis, Pneumococcal / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D011018:Pneumonia, Pneumococcal / Q000150:complications / Q000382:microbiology / Q000517:prevention & control*; D011446:Prospective Studies; D012621:Seasons; D065288:Serogroup; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification
chemical_list: C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines