title: Immunogenicity profile of a 3.75-μg hemagglutinin pandemic rH5N1 split virion AS03A-adjuvanted vaccine in elderly persons: a randomized trial.
abstract: BACKGROUND
  Elderly persons often experience a reduced immune response to influenza vaccination. We evaluated the usual dose of AS03(A)-adjuvanted H5N1 pandemic vaccine (3.75 μg hemagglutinin of A/Vietnam/1194/2004-like strain) compared with a double dose in an elderly population.
  
  
  METHODS
  This phase 2, open-label study (NCT00397215; http://www.clinicaltrials.gov) randomized participants (age, ≥61 years) to receive, on days 0 and 21: (1) a single dose of AS03(A)-adjuvanted vaccine (n=152), (2) a single dose of nonadjuvanted vaccine (n=54), (3) a double dose of AS03(A)-adjuvanted vaccine (n=145), or (4) a double dose of nonadjuvanted vaccine (n=44). The primary end point was hemagglutination inhibition (HI) and neutralizing antibody response against vaccine antigen (according-to-protocol cohort).
  
  
  RESULTS
  Day 42 geometric mean titers for HI antibodies were 126.8 and 237.3 for single and double doses of the AS03(A)-adjuvanted vaccine, respectively. Corresponding values for neutralizing antibodies were 447.3 and 595.8. Although the immune response was higher with the double dose, European Committee for Human Medicinal Products criteria for seroconversion and seroprotection rates were achieved in both AS03(A)-adjuvanted groups. Antigen-specific CD4 T cell responses were elicited. Immune response persistence at 6 months was high. Immune response in the non-adjuvanted groups was considerably less.
  
  
  CONCLUSIONS
  The AS03(A)-adjuvanted H5N1 vaccine can be administered elderly persons at the same dose and schedule as in younger adults.
authors: ResearchLink, Department Clinical Trial Network, Linkebeek, Flemish Brabant, Belgium. stephane.heijmans@researchlink.be
authors: Stéphane
authors: S
authors: Heijmans
authors: Marc
authors: M
authors: De Meulemeester
authors: Paul
authors: P
authors: Reynders
authors: Didier
authors: D
authors: Giet
authors: Etienne
authors: E
authors: Demanet
authors: Pierre-Yves
authors: PY
authors: Devresse
authors: Giancarlo
authors: G
authors: Icardi
authors: Mamadou
authors: M
authors: Dramé
authors: François
authors: F
authors: Roman
authors: Paul
authors: P
authors: Gillard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006388:Hemagglutinins / Q000235:genetics*; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged
chemical_list: D006388:Hemagglutinins; D007252:Influenza Vaccines