title: Homologous and heterologous antibody responses to a one-year booster dose of an MF59(®) adjuvanted A/H5N1 pre-pandemic influenza vaccine in pediatric subjects.
abstract: BACKGROUND
  Primary immunization with two doses of MF59 (®) -adjuvanted A/H5N1 influenza vaccine has been shown to be highly immunogenic and well tolerated in children and adolescents. Assessment of long-term antibody persistence after priming, and the effects of a one-year booster dose in children and adolescents was needed.
  
  
  OBJECTIVE
  This study assessed homologous and heterologous antibody responses to a one-year booster dose of MF59-adjuvanted A/H5N1 influenza vaccine in previously primed children.
  
  
  RESULTS
  Twelve months after primary vaccination, persistent, homologous, seroprotective HI antibody titers (≥ 40) were observed in 46%, 26% and 30% of toddlers, children and adolescents; following booster vaccination, seroprotection rates increased to 99%, 98% and 91%, respectively. All toddlers and children, and 99% of adolescents achieved MN antibody titers ≥ 40. Cross-reactive A/H5N1 antibodies were detected in 94-98% of subjects after booster vaccination.
  
  
  METHODS
  Twelve months after primary vaccination, toddlers, children and adolescents received a single booster dose of the same A/H5N1 vaccine. Paired sera were collected before and three weeks after booster vaccination. Homologous antibody responses against the A/Vietnam/1194/2004 vaccine strain were measured by hemagglutination inhibition (HI), single radial hemolysis (SRH) and microneutralization (MN) assays. Heterologous antibody responses against A/Indonesia/5/2005 and A/Anhui/1/2005 strains were assessed by MN assay only.
  
  
  CONCLUSIONS
  Two priming doses of MF59-adjuvanted A/H5N1 vaccine resulted in homologous and heterologous antibody responses which persisted for up to one year after immunization. A one-year booster dose was highly immunogenic, generating high homologous and cross-reactive A/H5N1 antibody titers.
authors: University of Tampere Medical School, Tampere, Finland. timo.vesikari@uta.fi
authors: Timo
authors: T
authors: Vesikari
authors: Aino
authors: A
authors: Forstén
authors: Astrid
authors: A
authors: Borkowski
authors: Nikolaos
authors: N
authors: Gaitatzis
authors: Angelika
authors: A
authors: Banzhoff
authors: Ralf
authors: R
authors: Clemens
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000293:Adolescent; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007117:Immunization, Secondary / Q000379:methods*; D007223:Infant; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D008297:Male; D011136:Polysorbates / Q000008:administration & dosage*; D013185:Squalene / Q000008:administration & dosage*
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D007252:Influenza Vaccines; C089950:MF59 oil emulsion; D011136:Polysorbates; D013185:Squalene