title: Decline in early childhood respiratory tract infections in the Norwegian mother and child cohort study after introduction of pneumococcal conjugate vaccination.
abstract: BACKGROUND
  The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the Norwegian Childhood Immunization Program in 2006. A substantial effectiveness of PCV7 immunization against invasive pneumococcal disease has been demonstrated, whereas evidence of its impact on respiratory tract infections are less consistent.
  
  
  METHODS
  This study included children participating in the Norwegian Mother and Child Cohort Study, which recruited pregnant women between 1999 and 2008. Maternal report of acute otitis media (AOM), lower respiratory tract infections (LRTIs) and asthma in the child was compared by PCV7 immunization status, as obtained from the Norwegian Immunization Registry. Generalized linear models with the log-link function were used to report adjusted relative risks (RRs) and 95% confidence intervals (CIs).
  
  
  RESULTS
  For children who had received 3 or more PCV7 immunizations by 12 months of age, the adjusted RRs of AOM and LRTIs between 12 and 18 months were 0.86 (95% CI: 0.81, 0.91) and 0.78 (95% CI: 0.70, 0.87) respectively, when compared with nonimmunized children. A reduced risk of AOM, RR 0.92 (95% CI: 0.90, 0.94), and LRTIs, RR 0.75 (95% CI: 0.71, 0.80), between 18 and 36 months of age was also identified among children who had received 3 or more immunizations by 18 months of age. No association was seen between PCV7 immunization and asthma at 36 months of age.
  
  
  CONCLUSIONS
  Reduced incidences of AOM and LRTIs before 36 months of age were observed among children immunized with PCV7 through the childhood immunization program.
authors.affiliation: Department of Chronic Diseases, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway. maria.christine.mag-nus@fhi.no
authors.forename: Maria C
authors.initials: MC
authors.lastname: Magnus
authors.forename: Didrik F
authors.initials: DF
authors.lastname: Vestrheim
authors.forename: Wenche
authors.initials: W
authors.lastname: Nystad
authors.forename: Siri Eldevik
authors.initials: SE
authors.lastname: Håberg
authors.forename: Hein
authors.initials: H
authors.lastname: Stigum
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: London
authors.forename: Marianne A R
authors.initials: MA
authors.lastname: Bergsaker
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Caugant
authors.forename: Ingeborg S
authors.initials: IS
authors.lastname: Aaberge
authors.forename: Per
authors.initials: P
authors.lastname: Nafstad
mesh_terms: D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data*; D015994:Incidence; D007223:Infant; D009664:Norway / Q000453:epidemiology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011247:Pregnancy; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000517:prevention & control; D011795:Surveys and Questionnaires
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines