title: Transmission of 2009 pandemic influenza A (H1N1) virus among healthcare personnel-Southern California, 2009.
abstract: OBJECTIVE
  In April 2009, 2009 pandemic influenza A (H1N1) (hereafter, pH1N1) virus was identified in California, which caused widespread illness throughout the United States. We evaluated pH1N1 transmission among exposed healthcare personnel (HCP) and assessed the use and effectiveness of personal protective equipment (PPE) early in the outbreak.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Two hospitals and 1 outpatient clinic in Southern California during March 28-April 24, 2009.
  
  
  METHODS
  Sixty-three HCP exposed to 6 of the first 8 cases of laboratory-confirmed pH1N1 in the United States.
  
  
  METHODS
  Baseline and follow-up questionnaires were used to collect demographic, epidemiologic, and clinical data. Paired serum samples were obtained to test for pH1N1-specific antibodies by microneutralization and hemagglutination-inhibition assays. Serology results were compared with HCP work setting, role, and self-reported PPE use.
  
  
  RESULTS
  Possible healthcare-associated pH1N1 transmission was identified in 9 (14%) of 63 exposed HCP; 6 (67%) of 9 seropositive HCP had asymptomatic infection. The highest attack rates occurred among outpatient HCP (6/19 [32%]) and among allied health staff (eg, technicians; 8/33 [24%]). Use of mask or N95 respirator was associated with remaining seronegative (P = .047). Adherence to PPE recommendations for preventing transmission of influenza virus and other respiratory pathogens was inadequate, particularly in outpatient settings.
  
  
  CONCLUSIONS
  pH1N1 transmission likely occurred in healthcare settings early in the pandemic associated with inadequate PPE use. Organizational support for a comprehensive approach to infectious hazards, including infection prevention training for inpatient- and outpatient-based HCP, is essential to improve HCP and patient safety.
authors.affiliation: Epidemic Intelligence Service, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA.
authors.forename: Jenifer L
authors.initials: JL
authors.lastname: Jaeger
authors.forename: Minal
authors.initials: M
authors.lastname: Patel
authors.forename: Nila
authors.initials: N
authors.lastname: Dharan
authors.forename: Kathy
authors.initials: K
authors.lastname: Hancock
authors.forename: Elissa
authors.initials: E
authors.lastname: Meites
authors.forename: Christine
authors.initials: C
authors.lastname: Mattson
authors.forename: Matt
authors.initials: M
authors.lastname: Gladden
authors.forename: David
authors.initials: D
authors.lastname: Sugerman
authors.forename: Saumil
authors.initials: S
authors.lastname: Doshi
authors.forename: Dianna
authors.initials: D
authors.lastname: Blau
authors.forename: Kathleen
authors.initials: K
authors.lastname: Harriman
authors.forename: Melissa
authors.initials: M
authors.lastname: Whaley
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.forename: Michele
authors.initials: M
authors.lastname: Ginsberg
authors.forename: Annie S
authors.initials: AS
authors.lastname: Kao
authors.forename: Paula
authors.initials: P
authors.lastname: Kriner
authors.forename: Stephen
authors.initials: S
authors.lastname: Lindstrom
authors.forename: Seema
authors.initials: S
authors.lastname: Jain
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Katz
authors.forename: Lyn
authors.initials: L
authors.lastname: Finelli
authors.forename: Sonja J
authors.initials: SJ
authors.lastname: Olsen
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Kallen
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D003428:Cross Infection / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission*; D004196:Disease Outbreaks / Q000517:prevention & control; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D007251:Influenza, Human / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D011481:Protective Clothing / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial