title: Identification of antigen and adjuvant doses resulting in optimal immunogenicity and antibody persistence up to 1 year after immunization with a pandemic A/H1N1 influenza vaccine in children 3 to < 9 years of age.
abstract: BACKGROUND
  In the development of pediatric A/H1N1 influenza vaccines, this study was performed to identify antigen and adjuvant doses providing optimal immunogenicity and antibody persistence to ensure long-term immunity after immunization with an adjuvanted A/H1N1 vaccine in children 3 to <9 years of age.
  
  
  METHODS
  Healthy children (N = 1357) were immunized with 1 of 8 investigational vaccine formulations ranging in antigen (3.75-30 µg) and MF59 adjuvant (Novartis Vaccines, Marburg, Germany; 0, 50 and 100% of standard dose). Each participant received 2 vaccine doses given 3 weeks apart. Immunogenicity was analyzed by hemagglutination inhibition assay in sera drawn 3, 4 and 6 weeks after first vaccination. Long-term antibody persistence was assessed 6 and 12 months after immunization. Vaccine safety was monitored throughout the study.
  
  
  RESULTS
  All MF59-adjuvanted vaccines were well tolerated and highly immunogenic, with adjuvanted formulations inducing antibody titers statistically superior to those of the nonadjuvanted vaccines. Each MF59-adjuvanted vaccine met all the US and European licensure criteria for influenza vaccines 3 weeks after the administration of a single dose; all nonadjuvanted formulations failed to meet licensure criteria at this time point. Antibody titers in response to a single vaccination with 7.5 µg antigen and a full dose of MF59 continued to meet all US and European licensure criteria up to 1 year after immunization.
  
  
  CONCLUSIONS
  A single dose of vaccine containing 7.5 µg A/California/7/2009 (H1N1) antigen and a full dose of MF59 adjuvant was found to be optimal for children 3 to <9 years of age.
authors.affiliation: Nassim and Associates, Pediatric Medicine, New Albany, IN, USA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Nassim
authors.forename: Shane
authors.initials: S
authors.lastname: Christensen
authors.forename: Dan
authors.initials: D
authors.lastname: Henry
authors.forename: Sandra
authors.initials: S
authors.lastname: Holmes
authors.forename: Matthew
authors.initials: M
authors.lastname: Hohenboken
authors.forename: Niranjan
authors.initials: N
authors.lastname: Kanesa-Thasan
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000009:adverse effects; D000914:Antibodies, Viral / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005858:Germany; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007114:Immunization / Q000009:adverse effects / Q000379:methods; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D011136:Polysorbates / Q000008:administration & dosage* / Q000009:adverse effects; D016037:Single-Blind Method; D013185:Squalene / Q000008:administration & dosage* / Q000009:adverse effects; D013997:Time Factors; D014481:United States
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D007252:Influenza Vaccines; C089950:MF59 oil emulsion; D011136:Polysorbates; D013185:Squalene