title: Prospective, randomized, placebo-controlled evaluation of the safety and immunogenicity of three lots of intranasal trivalent influenza vaccine among young children.
abstract: BACKGROUND
  Trivalent formulations of an experimental, cold-adapted, intranasal influenza (CAIV) vaccine have been shown to be safe, immunogenic and efficacious in young children.
  
  
  METHODS
  We evaluated the safety and immunogenicity of three consistency lots of CAIV in children 12 to 36 months of age randomized to one of five groups: Groups 1, 2 and 3 received separate lots containing A/Shenzhen/227/95 (H1N1), A/Wuhan/359/95(H3N2) and B/Harbin/7/94-like viral strains. Group 4 received an earlier efficacy trial lot which included a different H1N1 strain (A/Texas/36/91-like); and Group 5 received placebo. We performed strain-specific serum hemagglutination inhibition antibody levels against type A (H3N2 or H1N1) or type B as appropriate.
  
  
  RESULTS
  Overall 474 children received 2 doses, 2 months apart. Each lot was well-tolerated, and there were no significant group differences between consistency lots in the proportion of children with fever and local or systemic reactions after vaccination. The 3 consistency lots were not statistically different with regard to immunogenicity as measured by seroconversion or absolute geometric mean titer. Immune responses were more robust among initially seronegative children and for H3N2 and B strains than for H1N1 strains. After 2 doses of vaccine 97, 84 and 62% had hemagglutination inhibition titers > or = 1/32 against A/H3N2, B and H1N1 strains, respectively. For A/H3N2 only, immune responses after 1 dose of vaccine are similar to those seen after 2 doses.
  
  
  CONCLUSIONS
  Each consistency lot of CAIV is as or more immunogenic than a lot used in a large efficacy trial.
authors.affiliation: UCLA Center for Vaccine Research, Harbor-UCLA Medical Center, Torrance, CA, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Zangwill
authors.forename: J
authors.initials: J
authors.lastname: Droge
authors.forename: P
authors.initials: P
authors.lastname: Mendelman
authors.forename: S M
authors.initials: SM
authors.lastname: Marcy
authors.forename: S
authors.initials: S
authors.lastname: Partridge
authors.forename: C Y
authors.initials: CY
authors.lastname: Chiu
authors.forename: J
authors.initials: J
authors.lastname: Jing
authors.forename: S J
authors.initials: SJ
authors.lastname: Chang
authors.forename: I
authors.initials: I
authors.lastname: Cho
authors.forename: J I
authors.initials: JI
authors.lastname: Ward
mesh_terms: D000281:Administration, Intranasal; D000914:Antibodies, Viral / Q000097:blood; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000276:immunology*; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control* / Q000821:virology; D008297:Male; D011446:Prospective Studies; D014611:Vaccination
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines