title: Influenza A (H1N1) 2009 two-dose immunization of US children: an observer-blinded, randomized, placebo-controlled trial.
abstract: The goal of this pediatric clinical trial was to assess the safety and immunogenicity of two different doses of a monovalent inactivated pandemic (H1N1) 2009 vaccine in US children aged 6 months to 9 years of age. Randomized, observer-blinded, US multicenter phase 2 study assessing 2 doses of vaccine given 21 days apart in 474 children aged 6-35 months or 3-9 years. Children in each age group were randomly assigned to receive either a pandemic (H1N1) 2009 vaccine containing 7.5 or 15 μg of hemagglutinin (HA) or placebo in a 4:4:1 ratio. Primary outcome was hemagglutination inhibition (HI) antibody responses 21 days following each vaccination. Safety was monitored throughout the study. The first dose of either A H1N1 vaccine formulation was more immunogenic in children older than 3 years than in younger children. 45-50% of children aged 6-35 months and 69-75% of children aged 3-9 year-old attained HI titers of ≥ 1:40. A second dose of A H1N1 vaccine further increased HI antibody responses with seroprotection and seroconversion rates reaching 90-99% in both age groups. Interestingly, the pandemic (H1N1) 2009 vaccine formulations elicited similar rates of solicited and unsolicited injection site and systemic reactions as the placebo. The data therefore demonstrate the high level immunogenicity in infants and children of an (H1N1) 2009 influenza vaccine displaying a safety and reactogenicity profile similar to placebo.
authors.affiliation: Clinical Development Department, sanofi pasteur, 1541 Avenue Marcel Mérieux, 69280 Marcy l'Etoile, Lyon, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Plennevaux
authors.forename: Mark
authors.initials: M
authors.lastname: Blatter
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Cornish
authors.forename: Kerry
authors.initials: K
authors.lastname: Go
authors.forename: Daniel
authors.initials: D
authors.lastname: Kirby
authors.forename: Mostafa
authors.initials: M
authors.lastname: Wali
authors.forename: Mary-Kate
authors.initials: MK
authors.lastname: Reeves-Hoché
authors.forename: Martine
authors.initials: M
authors.lastname: Denis
mesh_terms: D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D005260:Female; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000276:immunology; D006801:Humans; D007117:Immunization, Secondary; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology / Q000517:prevention & control*; D008297:Male; D016037:Single-Blind Method; D015164:Vaccines, Inactivated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated