title: The use of oseltamivir during an influenza B outbreak in a chronic care hospital.
abstract: BACKGROUND
  Residents of nursing homes and long-term care facilities are at a higher risk of outbreaks of influenza and of serious complications of influenza than those in the community. In late July 2005, a 90-bed chronic care psycho-geriatric hospital in Sydney, Australia, reported cases of influenza-like illness (ILI) occurring amongst its residents.
  
  
  METHODS
  An investigation to confirm the outbreak, and its cause, was undertaken. Influenza vaccination levels amongst residents, and the effects of antiviral drugs used for prevention and treatment, were assessed. Oseltamivir was only given to the residents, in the form of both treatment and prophylaxis.
  
  
  RESULTS
  A total of 22 out of 89 residents met the clinical case definition of ILI with onset on or after 27 July 2005. This represents an attack rate of 25%. Oseltamivir was commenced on day 9 of the outbreak. Influenza B was identified in six residents as the causative agent of the outbreak. No deaths or acute hospitalization were recorded for this outbreak and there were no further reported cases after the introduction of oseltamivir. Vaccine effectiveness was 75% and the strain of influenza B isolated was well matched to that year's vaccine.
  
  
  CONCLUSIONS
  There are few data on the use of oseltamivir in influenza B outbreaks. Early antiviral intervention appeared to curtail this outbreak of influenza B in a chronic care facility. We found high vaccine effectiveness in this frail, institutionalized population, highlighting the importance of influenza vaccination for residents of chronic care facilities.
authors.affiliation: School of Public Health and Community Medicine, Faculty of Medicine, University of New South Wales, NSW, Australia. h.seale@unsw.edu.au
authors.forename: Holly
authors.initials: H
authors.lastname: Seale
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Weston
authors.forename: Dominic E
authors.initials: DE
authors.lastname: Dwyer
authors.forename: Mengzhi
authors.initials: M
authors.lastname: Zhu
authors.forename: Lisa
authors.initials: L
authors.lastname: Allchin
authors.forename: Robert
authors.initials: R
authors.lastname: Booy
authors.forename: C Raina
authors.initials: CR
authors.lastname: MacIntyre
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000627:therapeutic use*; D001315:Australia / Q000453:epidemiology; D018890:Chemoprevention / Q000379:methods; D003428:Cross Infection / Q000188:drug therapy* / Q000453:epidemiology* / Q000821:virology; D004196:Disease Outbreaks; D005260:Female; D006761:Hospitals; D006801:Humans; D009981:Influenza B virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000188:drug therapy* / Q000453:epidemiology* / Q000821:virology; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D053139:Oseltamivir / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir