title: Evaluation of haemophilus influenzae type b vaccine for routine immunization in Nepali infants.
abstract: BACKGROUND
  Haemophilus influenzae type b (Hib) carriage and disease studies in Nepali children suggest a significant burden of infection. Hib conjugate vaccines (HibCV) do not have uniform immunogenicity between populations. We determined the immunogenicity of HibCV in Nepali infants, before its introduction into the routine immunization schedule.
  
  
  METHODS
  Ninety infants recruited at Patan Hospital, Kathmandu, received 3 doses of the HibCV with routine immunizations (diphtheria, tetanus, whole cell pertussis-hepatitis B vaccine + oral polio vaccine) at 6, 10 and 14 weeks of age, and a HibCV booster at 52 weeks. Anti-polyribosylribitol phosphate (PRP) concentrations were measured at 18, 52 and 56 weeks, and the antibody persistence at 52 weeks was compared with antibody values in unimmunized controls (n = 30).
  
  
  RESULTS
  After 3 doses of primary immunizations, at 18 weeks of age (n = 74), all infants had anti-PRP concentrations above the accepted thresholds for short- and long-term protection (0.15 and 1.0 µg/mL, respectively). At 1 year of age, before administration of the booster of HibCV, the anti-PRP geometric mean antibody concentration was 2.76 µg/mL (confidence interval: 1.88-4.07) in sera from the immunized children compared with 0.11 µg/mL (95% confidence interval: 0.08-0.17) in the nonimmunized control group (n = 30). Twenty-seven percent (20/74) of participants, however, had anti-PRP concentrations <1.0 µg/mL. Four weeks after the booster dose of HibCV, 98.5% of infants had anti-PRP concentrations above 1.0 µg/mL.
  
  
  CONCLUSIONS
  Immunization with HibCV given as part of the Expanded Program on Immunization schedule in Nepal elicits robust antibody responses. Though the antibody wanes during the first year of life, most 1-year-old infants remain protected and respond robustly to a booster dose of the vaccine.
authors.affiliation: Department of Pediatrics, Oxford Vaccine Group, University of Oxford, UK. janemetz@gmail.com
authors.forename: Jane Astrid
authors.initials: JA
authors.lastname: Metz
authors.forename: Sarah
authors.initials: S
authors.lastname: Hanieh
authors.forename: Rahul
authors.initials: R
authors.lastname: Pradhan
authors.forename: Anip
authors.initials: A
authors.lastname: Joshi
authors.forename: Disuja
authors.initials: D
authors.lastname: Shakya
authors.forename: Lochan
authors.initials: L
authors.lastname: Shrestha
authors.forename: Amrita
authors.initials: A
authors.lastname: Shrestha
authors.forename: Bishwas
authors.initials: B
authors.lastname: Upadhyay
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Kelly
authors.forename: Tessa M
authors.initials: TM
authors.lastname: John
authors.forename: Bishnu Devi
authors.initials: BD
authors.lastname: Maharjan
authors.forename: Ly-Mee
authors.initials: LM
authors.lastname: Yu
authors.forename: Omar
authors.initials: O
authors.lastname: Omar
authors.forename: Raymond
authors.initials: R
authors.lastname: Borrow
authors.forename: Jamie
authors.initials: J
authors.lastname: Findlow
authors.forename: Dominic F
authors.initials: DF
authors.lastname: Kelly
authors.forename: Stephen Mark
authors.initials: SM
authors.lastname: Thorson
authors.forename: Neelam
authors.initials: N
authors.lastname: Adhikari
authors.forename: David Roger
authors.initials: DR
authors.lastname: Murdoch
authors.forename: Andrew John
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D002353:Carrier State / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D006192:Haemophilus Infections / Q000453:epidemiology / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D019741:Haemophilus influenzae type b / Q000276:immunology*; D006801:Humans; D007114:Immunization / Q000379:methods*; D007223:Infant; D008297:Male; D009390:Nepal / Q000453:epidemiology
chemical_list: C570267:Act-Hib vaccine; D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines