title: Effectiveness of Haemophilus influenzae type b conjugate vaccine on radiologically-confirmed pneumonia in young children in Pakistan.
abstract: OBJECTIVE
  The effectiveness of Haemophilus influenzae type b (Hib) vaccine in preventing severe pneumonia in Asian children has been questioned, and many large Asian countries yet to introduce Hib conjugate vaccine in immunization programs. The primary objective of this study was to assess Hib conjugate vaccine effectiveness (VE) on radiologically-confirmed pneumonia in children born after introduction of Hib conjugate vaccine in Pakistan.
  
  
  METHODS
  A matched case-control study enrolled cases of radiologically-confirmed pneumonia in several hospitals serving low-income populations during 2009-2011. Cases were matched by age and season with 3 hospital and 5 neighborhood controls. Pneumonia was diagnosed using standardized World Health Organization criteria for chest radiograph interpretation. Matched OR were estimated for VE.
  
  
  RESULTS
  A total of 1027 children with radiologically-confirmed pneumonia were enrolled; 975 cases, 2925 hospital controls, and 4875 neighborhood controls were analyzed. The coverage for 3 doses of diphtheria-tetanus-pertussis-hepatitis B-Hib conjugate vaccine was 13.7%, 18%, and 22.7% in cases, hospital controls and neighborhood controls, respectively. Estimated Hib VE for radiologically-confirmed pneumonia was 62% with 3 doses of vaccine using hospital controls and 70% using neighborhood controls.
  
  
  CONCLUSIONS
  Hib conjugate vaccine prevented a significant fraction of radiologically-confirmed pneumonia in children in Pakistan. Maximizing impact on child survival needs improved immunization coverage.
authors.affiliation: Department of Pediatrics and Child Health, Aga Khan University, Karachi, Pakistan.
authors.forename: Asif Raza
authors.initials: AR
authors.lastname: Khowaja
authors.forename: Syed
authors.initials: S
authors.lastname: Mohiuddin
authors.forename: Adam L
authors.initials: AL
authors.lastname: Cohen
authors.forename: Waseem
authors.initials: W
authors.lastname: Mirza
authors.forename: Naila
authors.initials: N
authors.lastname: Nadeem
authors.forename: Talha
authors.initials: T
authors.lastname: Zuberi
authors.forename: Basit
authors.initials: B
authors.lastname: Salam
authors.forename: Fatima
authors.initials: F
authors.lastname: Mubarak
authors.forename: Bano
authors.initials: B
authors.lastname: Rizvi
authors.forename: Yousuf
authors.initials: Y
authors.lastname: Husen
authors.forename: Khatidja
authors.initials: K
authors.lastname: Pardhan
authors.forename: Khalid Mehmood A
authors.initials: KM
authors.lastname: Khan
authors.forename: Syed Jamal
authors.initials: SJ
authors.lastname: Raza
authors.forename: Hassan Khalid
authors.initials: HK
authors.lastname: Zuberi
authors.forename: Sultan
authors.initials: S
authors.lastname: Mustafa
authors.forename: Salma H
authors.initials: SH
authors.lastname: Sheikh
authors.forename: Akbar
authors.initials: A
authors.lastname: Nizamani
authors.forename: Heermani
authors.initials: H
authors.lastname: Lohana
authors.forename: Kim
authors.initials: K
authors.lastname: Mulholland
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Zell
authors.forename: Rana
authors.initials: R
authors.lastname: Hajjeh
authors.forename: Altaf
authors.initials: A
authors.lastname: Bosan
authors.forename: Anita K M
authors.initials: AK
authors.lastname: Zaidi
mesh_terms: D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D006192:Haemophilus Infections / Q000000981:diagnostic imaging / Q000276:immunology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000008:administration & dosage*; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D008297:Male; D010154:Pakistan / Q000453:epidemiology; D018410:Pneumonia, Bacterial / Q000000981:diagnostic imaging / Q000276:immunology / Q000517:prevention & control*; D011203:Poverty; D011859:Radiography; D018074:Vaccines, Conjugate / Q000008:administration & dosage
chemical_list: D018073:Haemophilus Vaccines; D018074:Vaccines, Conjugate