title: Influenza vaccination is safe and immunogenic when administered to hospitalized patients.
abstract: BACKGROUND
  Very few high-risk persons receive influenza vaccine while hospitalized. Health care providers may be reluctant to administer the influenza vaccine to hospitalized patients because of insufficient data related to the safety and immunogenicity of vaccinating this population.
  
  
  OBJECTIVE
  To evaluate the safety and immunogenicity of the influenza vaccine administered to hospitalized patients compared to ambulatory clinic patients.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  A 711-bed, acute-care, private tertiary hospital and two private internal medicine clinics from October 1 to December 25, 1999.
  
  
  METHODS
  51 inpatients; 177 outpatients.
  
  
  METHODS
  All study participants received influenza vaccine. Serum samples for antibody assays were collected at baseline and at 3 weeks after vaccination. Study participants were mailed a questionnaire to elicit information about adverse effects of vaccination.
  
  
  METHODS
  Seroconversion rates (4-fold increase in hemagglutination-inhibiting antibodies) and seroprotection rates (titers > or = 1:40) to the influenza vaccine in hospitalized and ambulatory patients.
  
  
  RESULTS
  The seroconversion and post-vaccination seroprotection rates in the inpatient group were 65% (33/51) and 88% (45/51) compared to 55% (98/177) and 94% (167/177) in the ambulatory clinic patients. Soreness at the site of injection was the most common adverse effect, reported by 12% of both the inpatients (5/42) and ambulatory clinic patients (20/171). Seventy-four percent of patients (31/41 inpatients and 127/174 outpatients) reported no significant side effect to vaccination.
  
  
  CONCLUSIONS
  Influenza vaccine is at least as safe and immunogenic in hospitalized patients as it is in ambulatory patients. These data can be used to help convince health care providers to order the influenza vaccine for their hospitalized patients.
authors.affiliation: Quality Improvement, Aurora Health Care, 3305 West Forest Home Avenue, PO Box 343910, Milwaukee, WI 53215, USA. bruce_berry@aurora.org
authors.forename: B B
authors.initials: BB
authors.lastname: Berry
authors.forename: D A
authors.initials: DA
authors.lastname: Ehlert
authors.forename: R J
authors.initials: RJ
authors.lastname: Battiola
authors.forename: G
authors.initials: G
authors.lastname: Sedmak
mesh_terms: D000368:Aged; D000553:Ambulatory Care; D000914:Antibodies, Viral / Q000097:blood; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012449:Safety; D014922:Wisconsin
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines