title: Immunogenicity and Efficacy of A/H1N1pdm Vaccine Among Subjects With Severe Motor and Intellectual Disability in the 2010/11 Influenza Season.
abstract: BACKGROUND
  While the immunogenicity and effectiveness of seasonal influenza vaccines among subjects with severe motor and intellectual disability (SMID) are known to be diminished, the efficacy of the A/H1N1pdm vaccine has not been evaluated.
  
  
  METHODS
  We prospectively evaluated 103 subjects with SMID (mean age, 41.7 years) who received trivalent inactivated influenza vaccine during the 2010/11 influenza season. The hemagglutination inhibition (HI) antibody titer was measured in serum samples collected pre-vaccination (S0), post-vaccination (S1), and end-of-season (S2) to evaluate subjects' immunogenicity capacity. Vaccine efficacy was assessed based on antibody efficacy and achievement proportion.
  
  
  RESULTS
  The proportions of seroprotection and seroconversion, and the geometric mean titer (GMT) ratio (GMT at S1/GMT at S0) for A/H1N1pdm were 46.0%, 16.0%, and 1.8, respectively-values which did not meet the European Medicines Evaluation Agency criteria. The achievement proportion was 26%. During follow-up, 11 of 43 subjects with acute respiratory illness were diagnosed with type A influenza according to a rapid influenza diagnostic test (RIDT), and A/H1N1pdm strains were isolated from the throat swabs of 5 of those 11 subjects. When either or both RIDT-diagnosed influenza or serologically diagnosed influenza (HI titer at S2/HI titer at S1 ≥2) were defined as probable influenza, subjects with A/H1N1pdm seroprotection were found to have a lower incidence of probable influenza (odds ratio, 0.31; antibody efficacy, 69%; vaccine efficacy, 18%).
  
  
  CONCLUSIONS
  In the present seasonal assessment, antibody efficacy was moderate against A/H1N1pdm among SMID subjects, but vaccine efficacy was low due to the reduced immunogenicity of SMID subjects.
authors.affiliation: Department of Preventive Medicine, Faculty of Medicine, Saga University.
authors.forename: Megumi
authors.initials: M
authors.lastname: Hara
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hanaoka
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Maeda
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kase
authors.forename: Satoko
authors.initials: S
authors.lastname: Ohfuji
authors.forename: Wakaba
authors.initials: W
authors.lastname: Fukushima
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirota
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D000071497:Immunogenicity, Vaccine; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D008607:Intellectual Disability / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D000068079:Motor Disorders / Q000276:immunology*; D011446:Prospective Studies; D012621:Seasons; D012720:Severity of Illness Index
chemical_list: D007252:Influenza Vaccines