title: Effectiveness of the 10-Valent Pneumococcal Conjugate Vaccine (PCV-10) in Children in Chile: A Nested Case-Control Study Using Nationwide Pneumonia Morbidity and Mortality Surveillance Data.
abstract: BACKGROUND
  The ten-valent pneumococcal conjugate vaccine (PCV10) was introduced into the Chilean National Immunization Program (NIP) in January 2011 with a 3+1 schedule (2, 4, 6 and 12 months) without catch-up vaccination. We evaluated the effectiveness of PCV10 on pneumonia morbidity and mortality among infants during the first two years after vaccine introduction.
  
  
  METHODS
  This is a population-based nested case-control study using four merged nationwide case-based electronic health data registries: live birth, vaccination, hospitalization and mortality. Children born in 2010 and 2011 were followed from two moths of age for a period of two years. Using four different case definitions of pneumonia hospitalization and/or mortality (all-cause and pneumonia related deaths), all cases and four randomly selected matched controls per case were selected. Controls were matched to cases on analysis time. Vaccination status was then assessed. Vaccine effectiveness (VE) was estimated using conditional logistic regression.
  
  
  RESULTS
  There were a total of 497,996 children in the 2010 and 2011 Chilean live-birth cohorts. PCV10 VE was 11.2% (95%CI 8.5-13.6) when all pneumonia hospitalizations and deaths were used to define cases. VE increased to 20.7 (95%CI 17.3-23.8) when ICD10 codes used to denote viral pneumonia were excluded from the case definition. VE estimates on pneumonia deaths and all-cause deaths were 71.5 (95%CI 9.0-91.8) and 34.8 (95% CI 23.7-44.4), respectively.
  
  
  CONCLUSIONS
  PCV10 vaccination substantially reduced the number of hospitalizations due to pneumonia and deaths due to pneumonia and to all-causes over this study period. Our findings also reinforce the importance of having quality health information systems for measuring VE.
authors.affiliation: National Institute of Health, Santiago, Chile.
authors.forename: Janepsy
authors.initials: J
authors.lastname: Diaz
authors.affiliation: National Institute of Health, Santiago, Chile.
authors.forename: Solana
authors.initials: S
authors.lastname: Terrazas
authors.affiliation: Sanas - epidemiologia e pesquisa, São Paulo, Brazil.
authors.forename: Ana L
authors.initials: AL
authors.lastname: Bierrenbach
authors.affiliation: Department of Community Health, Institute of Tropical Pathology and Public Health, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Cristiana M
authors.initials: CM
authors.lastname: Toscano
authors.affiliation: School of Public Health, University of São Paulo, São Paulo, Brazil.
authors.forename: Gizelton P
authors.initials: GP
authors.lastname: Alencar
authors.affiliation: Department of Statistics and Health Information, Ministry of Health, Santiago, Chile.
authors.forename: Andrés
authors.initials: A
authors.lastname: Alvarez
authors.affiliation: Medical School, University de los Andes, Santiago, Chile.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Valenzuela
authors.affiliation: Sabin Vaccine Institute, Washington, DC, United States of America.
authors.forename: Jon
authors.initials: J
authors.lastname: Andrus
authors.affiliation: Pan American Health Organization, PWR-Chile, Santiago, Chile.
authors.forename: Roberto
authors.initials: R
authors.lastname: del Aguila
authors.affiliation: National Institute of Health, Santiago, Chile.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Hormazábal
authors.affiliation: National Institute of Health, Santiago, Chile.
authors.forename: Pamela
authors.initials: P
authors.lastname: Araya
authors.affiliation: National Institute of Health, Santiago, Chile.
authors.forename: Paola
authors.initials: P
authors.lastname: Pidal
authors.affiliation: Comprehensive Family Immunization Project, Pan American Health Organization, Washington, DC, United States of America.
authors.forename: Cuauhtemoc R
authors.initials: CR
authors.lastname: Matus
authors.affiliation: Comprehensive Family Immunization Project, Pan American Health Organization, Washington, DC, United States of America.
authors.forename: Lucia H
authors.initials: LH
authors.lastname: de Oliveira
mesh_terms: D016022:Case-Control Studies; D002675:Child, Preschool; D002677:Chile / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D017589:Immunization Programs; D007115:Immunization Schedule; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D009017:Morbidity; D009313:National Health Programs; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000494:pharmacology*; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control*; D012042:Registries; D016896:Treatment Outcome; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: C586648:10-valent pneumococcal conjugate vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate