title: Pandemic 2009 influenza A (H1N1) virus among Japanese healthcare workers: seroprevalence and risk factors.
abstract: OBJECTIVE
  To evaluate the seroprevalence and risk factors for 2009 influenza A (H1N1) virus infection among healthcare personnel.
  
  
  METHODS
  Observational cross-sectional study.
  
  
  METHODS
  Healthcare workers (HCWs) in an acute care hospital.
  
  
  METHODS
  Between September 14 and October 4, 2009, before 2009 H1N1 vaccination, we collected serological samples from 461 healthy HCWs. Hemagglutination-inhibition antibody assays were conducted. To evaluate the risk factors of seropositivity for 2009 H1N1 virus, gender, age, profession, work department, usage of personal protective equipment, and seasonal influenza vaccination status data were gathered via questionnaires.
  
  
  RESULTS
  Our survey showed that doctors and nurses were at highest risk of seropositivity for the 2009 H1N1 virus (odds ratio [OR], 5.25 [95% confidence interval {CI}, 1.21-22.7]). An increased risk of seropositivity was observed among pediatric, emergency room, and internal medicine staff (adjusted OR, 1.98 [95% CI, 1.07-3.65]). Risk was also higher among HCWs who had high titers of antibodies against the seasonal H1N1 virus (adjusted OR, 1.59 [95% CI, 1.02-2.48]).
  
  
  CONCLUSIONS
  Seropositivity for the 2009 H1N1 virus was associated with occupational risk factors among HCWs.
authors.affiliation: Department of Infection Control and Prevention, University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nukui
authors.forename: Shuji
authors.initials: S
authors.lastname: Hatakeyama
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kitazawa
authors.forename: Tamami
authors.initials: T
authors.lastname: Mahira
authors.forename: Yoshizumi
authors.initials: Y
authors.lastname: Shintani
authors.forename: Kyoji
authors.initials: K
authors.lastname: Moriya
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D016017:Odds Ratio; D010564:Personnel, Hospital; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D011795:Surveys and Questionnaires; D014611:Vaccination; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral