title: Antibody response to influenza A(H1N1)pdm09 among healthcare personnel receiving trivalent inactivated vaccine: effect of prior monovalent inactivated vaccine.
abstract: BACKGROUND
  Few data are available on the immunogenicity of repeated annual doses of influenza A(H1N1)pdm09-containing vaccines.
  
  
  METHODS
  We enrolled healthcare personnel (HCP) in direct patient care during the autumn of 2010 at 2 centers with voluntary immunization. We verified the receipt of A(H1N1)pdm09-containing monovalent inactivated influenza vaccine (MIIV) and 2010-2011 trivalent inactivated vaccine (TIV). We performed hemagglutination inhibition antibody (HI) assays on preseason, post-TIV, and end-of-season serum samples. We compared the proportion of HCPs with HI titer ≥ 40 against A(H1N1)pdm09 per receipt of prior-season MIIV, current-season TIV, both, or neither.
  
  
  RESULTS
  At preseason (n = 1417), HI ≥ 40 was significantly higher among those who received MIIV (34%) vs those who did not (14%) (adjusted relative risk [ARR], 3.26; 95% confidence interval [CI], 2.72-3.81). At post-TIV (n = 865), HI ≥ 40 was lower among HCP who received MIIV and TIV (66%) than among those receiving only TIV (85%) (ARR, 0.93 [95% CI, .84-.997]). At end-of-season (n = 1254), HI ≥ 40 was 40% among those who received both MIIV and TIV and 67% among those receiving only TIV (ARR, 0.76 [95% CI, .65-.88]), 52% among those who received MIIV only, and 12% among those receiving neither.
  
  
  CONCLUSIONS
  HCP immunization programs should consider effects of host immune response and vaccine antigenic distance on immunogenicity of repeated annual doses of influenza vaccines.
authors.affiliation: Division of Pediatric Infectious Diseases.
authors.forename: Manjusha
authors.initials: M
authors.lastname: Gaglani
authors.forename: Sarah
authors.initials: S
authors.lastname: Spencer
authors.forename: Sarah
authors.initials: S
authors.lastname: Ball
authors.forename: Juhee
authors.initials: J
authors.lastname: Song
authors.forename: Allison
authors.initials: A
authors.lastname: Naleway
authors.forename: Emily
authors.initials: E
authors.lastname: Henkle
authors.forename: Sam
authors.initials: S
authors.lastname: Bozeman
authors.forename: Sue
authors.initials: S
authors.lastname: Reynolds
authors.forename: Wendy
authors.initials: W
authors.lastname: Sessions
authors.forename: Kathy
authors.initials: K
authors.lastname: Hancock
authors.forename: Mark
authors.initials: M
authors.lastname: Thompson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D000917:Antibody Formation; D000918:Antibody Specificity; D015331:Cohort Studies; D005260:Female; D006282:Health Personnel; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000145:classification / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D015164:Vaccines, Inactivated; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated
keywords: 2009 influenza pandemic H1N1; healthcare workers; hemagglutination inhibition antibody; influenza vaccine; influenza vaccine immunogenicity or response