title: Immunogenicity of trivalent influenza vaccine in extremely low-birth-weight, premature versus term infants.
abstract: BACKGROUND
  Influenza vaccine immunogenicity in premature infants is incompletely characterized.
  
  
  OBJECTIVE
  To assess the immunogenicity of trivalent, inactivated influenza vaccine (TIV) in extremely low-birth-weight (≤ 1000 g birth weight) premature (<30 weeks gestation) infants. We hypothesized that geometric mean titers of influenza antibody would be lower in premature than in full-term (FT) (≥ 37 week) infants.
  
  
  METHODS
  In this prospective multicenter study, former premature and FT infants who were 6 to 17 months of age received 2 doses of TIV during the 2006-2007 or 2007-2008 influenza seasons. Sera were drawn before dose 1, and 4 to 6 weeks after dose 2. Antibody was measured by hemagglutination inhibition.
  
  
  RESULTS
  Over 2 years, 41 premature and 42 FT infants were enrolled; 36 and 33 of these infants, respectively, had postvaccination titers available. Premature infants weighed less (mean, 1.3-1.8 kg difference) at the time of immunization than FT infants. Prevaccination titers did not differ between groups. Premature infants had higher postvaccination antibody geometric mean titers than FT infants to H1 (2006-2007, 1:513 vs. 1:91, P = 0.03; 2007-2008, 1:363 vs. 1:189, P = 0.02) and B/Victoria (2006-2007, 1:51 vs. 1:10, P = 0.02). More premature than FT infants had antibody titers ≥ 1:32 to B/Victoria (85% vs. 60%, P = 0.04) in 2007-2008. Two (5%) premature and 8 (19%) FT infants had adverse events, primarily fever, within 72 hours after vaccination. No child had medically diagnosed influenza.
  
  
  CONCLUSIONS
  Former premature infants had antibody responses to 2 TIV doses higher than or equal to those of FT children. Two TIV doses are immunogenic and well tolerated in extremely low-birth-weight, premature infants 6 to 17 months old.
authors.affiliation: Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA. carl_dangio@urmc.rochester.edu
authors.forename: Carl T
authors.initials: CT
authors.lastname: D'Angio
authors.forename: Roy J
authors.initials: RJ
authors.lastname: Heyne
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Duara
authors.forename: Lucy C
authors.initials: LC
authors.lastname: Holmes
authors.forename: T Michael
authors.initials: TM
authors.lastname: O'Shea
authors.forename: Hongyue
authors.initials: H
authors.lastname: Wang
authors.forename: Dongwen
authors.initials: D
authors.lastname: Wang
authors.forename: Pablo J
authors.initials: PJ
authors.lastname: Sánchez
authors.forename: Robert C
authors.initials: RC
authors.lastname: Welliver
authors.forename: Rita M
authors.initials: RM
authors.lastname: Ryan
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Schnabel
authors.forename: Caroline B
authors.initials: CB
authors.lastname: Hall
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007117:Immunization, Secondary / Q000379:methods; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D008297:Male; D047928:Premature Birth; D011446:Prospective Studies; D014611:Vaccination / Q000379:methods; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated