title: Impact of ten-valent pneumococcal conjugate vaccine on pneumonia in Finnish children in a nation-wide population-based study.
abstract: BACKGROUND
  The ten-valent pneumococcal conjugate vaccine (PCV10) was introduced into the Finnish National Vaccination Program (NVP) in September 2010 using a 2+1 schedule (3, 5, 12 months). We estimated the direct and indirect effects of PCV10 on pneumonia among children to evaluate the public health impact of the vaccine.
  
  
  METHODS
  We conducted a nation-wide population-based, observational study comparing rates of pneumonia in children before and after the NVP introduction. For the total (direct and indirect) effect, the cohort of vaccine-eligible children (born June 1, 2010 or later) was followed until the end of 2013 (age range 3-42 months). For the indirect effect, a cohort of older children (age range 7-71 months) not eligible for the PCV vaccination was followed from 2011 to 2013. Both cohorts were compared with two season- and age-matched reference cohorts before NVP introduction. Hospitals' in- and outpatient discharge notifications with ICD-10 diagnoses compatible with pneumonia (J10.0, J11.0, J12-J18, J85.1 or J86) as set by the hospital pediatricians were collected from the national Care Register. The main outcome was hospital-treated primary pneumonia (HTPP), defined as primary diagnosis of pneumonia after in-patient hospitalization. We compared rates of pneumonia in the NVP target and reference cohorts by using Poisson regression models.
  
  
  RESULTS
  The rate of HTPP episodes was 5.3/1000 person-years in the combined reference cohorts and 4.1/1000 person-years in the target cohort vaccine-eligible children. Compared with the reference cohort, the relative rate reduction in target cohort was 23% (95%CI 18-28) and the absolute reduction 1.3/1000 person-years. In the indirect effect evaluation, we observed continued increase in HTPP incidence until 2011 with a subsequent reduction of 18% (95%CI 10-25) during years 2012 to 2013. Number of empyema diagnoses remained low.
  
  
  CONCLUSIONS
  A substantial decrease in pneumonia rates was observed both among vaccine-eligible children and among older, unvaccinated children after PCV10 introduction.
authors.affiliation: Department of Public Health Solutions, National Institute for Health and Welfare, Tampere, Finland.
authors.forename: Arto A
authors.initials: AA
authors.lastname: Palmu
authors.affiliation: Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Rinta-Kokko
authors.affiliation: Department of Health Security, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Nohynek
authors.affiliation: Department of Health Security, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: J Pekka
authors.initials: JP
authors.lastname: Nuorti
authors.affiliation: Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Terhi M
authors.initials: TM
authors.lastname: Kilpi
authors.affiliation: Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Jokinen
mesh_terms: D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008954:Models, Biological; D009313:National Health Programs; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology* / Q000517:prevention & control*; D012042:Registries
chemical_list: D022242:Pneumococcal Vaccines