title: Hospital-acquired influenza in an Australian sentinel surveillance system.
abstract: OBJECTIVE
  To review cases of nosocomial influenza and compare the epidemiology, clinical characteristics and outcomes with community-acquired cases.
  
  
  METHODS
  Prospective case series of adults hospitalised with influenza during April - November of 2010 and 2011 using a hospital-based sentinel surveillance system. A nosocomial case was defined as polymerase chain reaction-confirmed influenza where symptom onset was more than 2 15s after admission or, if this was not known, where the date of the positive test was more than 7 15s after admission.
  
  
  METHODS
  Demographic, clinical and outcome measures for patients with nosocomial influenza compared with patients admitted with community-acquired influenza.
  
  
  RESULTS
  In 2010-2011, 598 cases of influenza were detected, of which 26 (4.3%) were nosocomial. All patients with nosocomial influenza had chronic comorbidities, compared with 71.7% of patients (410/572) with community-acquired influenza (P = 0.001). Similar proportions of community-acquired (32.5%) and nosocomial (36.4%) cases occurred in patients vaccinated in the current season. Clinical findings at time of enrollment did not differ between the two groups, with similar rates of fever, cough, chest pain and dyspnoea. Compared with community-acquired cases, a higher proportion of patients with nosocomial influenza received neuraminidase inhibitors within 2 15s of symptom onset (38.5% v 15.9%; P = 0.003). Admission to intensive care took place in 21.3% and 23.1% of community-acquired and nosocomial cases, respectively. One death from nosocomial influenza occurred in a patient with end-stage respiratory disease.
  
  
  CONCLUSIONS
  Nosocomial influenza is uncommon but may be associated with severe disease. It may be partially preventable as patients frequently have comorbidities for which influenza vaccination is recommended. Patients, particularly those at high risk of complications, and their contacts (including health care workers) should be vaccinated to prevent severe disease.
authors.affiliation: Infectious Diseases Unit, Alfred Health, Melbourne, VIC, Australia.
authors.forename: Nenad
authors.initials: N
authors.lastname: Macesic
authors.forename: Tom C
authors.initials: TC
authors.lastname: Kotsimbos
authors.forename: Paul
authors.initials: P
authors.lastname: Kelly
authors.forename: Allen C
authors.initials: AC
authors.lastname: Cheng
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000998:Antiviral Agents / Q000627:therapeutic use; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology; D015897:Comorbidity; D003428:Cross Infection / Q000453:epidemiology*; D004363:Drug Utilization / Q000706:statistics & numerical data; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D005260:Female; D006801:Humans; D016867:Immunocompromised Host; D007223:Infant; D007231:Infant, Newborn; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000188:drug therapy / Q000453:epidemiology* / Q000635:transmission; D007362:Intensive Care Units / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009439:Neuraminidase / Q000037:antagonists & inhibitors; D011446:Prospective Studies; D018571:Sentinel Surveillance; D061665:Time-to-Treatment; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D007252:Influenza Vaccines; D009439:Neuraminidase