title: A phase III, randomized, open-label study to assess the tolerability and immunogenicity of an H5N1 influenza vaccine administered to healthy adults with a 1-, 2-, 3-, or 6-week interval between first and second doses.
abstract: BACKGROUND
  Preparedness for an H5N1 influenza pre-pandemic requires effective and well-tolerated emergency vaccination strategies that provide both pandemic strain-specific and heterologous protection.
  
  
  OBJECTIVE
  This was a pivotal study for the regulatory approval process for a candidate MF59-adjuvanted H5N1 vaccine. Its goals were to identify the preferred primary 2-dose vaccination schedule in adults and to assess whether the vaccine met European Committee for Medicinal Products for Human Use (CHMP) licensure criteria.
  
  
  METHODS
  Healthy volunteers aged 18 to 60 years received 1 of 4 randomized schedules in which the 2 doses of vaccine were separated by a 1-, 2-, 3-, or 6-week interval. Three blood samples (~20 mL(-1)) were obtained from each subject: the first sample, immediately before administration of the first dose of vaccine; the second, immediately before administration of the second dose; and the third, 21 days after administration of the second dose. Hemagglutination inhibition (HI), microneutralization (MN), and single radial hemolysis (SRH) were assayed after each dose. Immunogenicity was assessed based on the CHMP licensure criteria for annual influenza vaccines (number of seroconversions or significant increase in HI titer >40%; mean geometric increase >2.5; and proportion of subjects achieving an HI titer ≥40 or SRH titer >25 mm(2) should be >70% [seroprotection]). Subjects recorded all adverse events occurring within 7 days of vaccine administration; information on any serious adverse events was collected throughout the study (duration, 202 days).
  
  
  RESULTS
  All study participants (N = 240) were white, with a mean age of 33 years and a mean body mass index of 24.6 kg/m(2). Equal numbers of men and women were assigned to each vaccination schedule. The CHMP criterion for seroprotection was achieved when the 2 doses of vaccine were separated by 2 (76%), 3 (72%), and 6 (79%) weeks; similar results were obtained on MN and SRH analysis. On the SRH analysis, the candidate vaccine showed a heterologous immune response to the H5N1/turkey/Turkey/1/05 (NIBRG-23; clade 2) influenza antigen. The vaccine met 2 of the 3 European licensure criteria, with seroconversion rates of 69% and 65% in the groups assigned to a 2- and 3-week interval between doses, respectively, and geometric mean ratios of 4.3 and 4.5. There were no serious adverse events related to vaccination. The most common adverse events reported within 7 days of the first and second doses of vaccine were mild to moderate injection-site pain (63%-73% and 34%-48%, respectively) and fatigue (25%-30% and 13%-24%).
  
  
  CONCLUSIONS
  Two 7.5-μg doses of MF59-adjuvanted H5N1 influenza vaccine given 2, 3, or 6 weeks apart afforded H5N1-specific immunity and met the CHMP licensure criterion for seroprotection in these healthy volunteers. Clinically relevant levels of heterologous immunity were observed when the 2 doses of vaccine were administered either 2 or 3 weeks apart; however, the licensure criterion for seroprotection was not met in this case.
authors.affiliation: Vaccination and Travel Medicine Center, Poliklinika II, Hradec Králové, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Beran
authors.forename: Ibrahim A
authors.initials: IA
authors.lastname: Abdel-Messih
authors.forename: Jolana
authors.initials: J
authors.lastname: Raupachova
authors.forename: Lenka
authors.initials: L
authors.lastname: Hobzova
authors.forename: Elena
authors.initials: E
authors.lastname: Fragapane
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D004334:Drug Administration Schedule; D005260:Female; D006384:Hemagglutination / Q000187:drug effects; D006385:Hemagglutination Inhibition Tests; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D007117:Immunization, Secondary; D007156:Immunologic Memory / Q000187:drug effects; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D007251:Influenza, Human / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D011136:Polysorbates / Q000008:administration & dosage / Q000009:adverse effects; D013185:Squalene / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D007252:Influenza Vaccines; C089950:MF59 oil emulsion; D011136:Polysorbates; D013185:Squalene