title: Assessing the use of hospital staff influenza-like absence (ILA) for enhancing hospital preparedness and national surveillance.
abstract: BACKGROUND
  Early warning and robust estimation of influenza burden are critical to inform hospital preparedness and operational, treatment, and vaccination policies. Methods to enhance influenza-like illness (ILI) surveillance are regularly reviewed. We investigated the use of hospital staff 'influenza-like absences' (hospital staff-ILA), i.e. absence attributed to colds and influenza, to improve capture of influenza dynamics and provide resilience for hospitals.
  
  
  METHODS
  Numbers and rates of hospital staff-ILA were compared to regional surveillance data on ILI primary-care presentations (15-64 years) and to counts of laboratory confirmed cases among hospitalised patients from April 2008 to April 2013 inclusive. Analyses were used to determine comparability of the ILI and hospital-ILA and how systems compared in early warning and estimating the burden of disease.
  
  
  RESULTS
  Among 20,021 reported hospital-ILA and 4661 community ILI cases, correlations in counts were high and consistency in illness measurements was observed. In time series analyses, both hospital-ILA and ILI showed similar timing of the seasonal component. Hospital-ILA data often commenced and peaked earlier than ILI according to a Bayesian prospective alarm algorithm. Hospital-ILA rates were more comparable to model-based estimates of 'true' influenza burden than ILI.
  
  
  CONCLUSIONS
  Hospital-ILA appears to have the potential to be a robust, yet simple syndromic surveillance method that could be used to enhance estimates of disease burden and early warning, and assist with local hospital preparedness.
authors.affiliation: Department of Medicine, University of Cambridge, Cambridge, UK. lnd23@medschl.cam.ac.uk.|National Centre for Infection Prevention and Management and National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infection and Antimicrobial Resistance Imperial College London, London, UK. lnd23@medschl.cam.ac.uk.
authors.forename: Lydia N
authors.initials: LN
authors.lastname: Drumright
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK. sdf22@cam.ac.uk.
authors.forename: Simon D W
authors.initials: SD
authors.lastname: Frost
authors.affiliation: Real-time Syndromic Surveillance Team, Public Health England, Birmingham, UK. alex.elliot@phe.gov.uk.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Elliot
authors.affiliation: Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK. mike.catchpole@ecdc.europa.eu.
authors.forename: Mike
authors.initials: M
authors.lastname: Catchpole
authors.affiliation: Centre for Infectious Disease Surveillance and Control, Public Health England, London, UK. richard.pebody@phe.gov.uk.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Pebody
authors.affiliation: Department of Virology, Imperial College Healthcare NHS Trust, London, UK. m.atkins@imperial.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Atkins
authors.affiliation: Department of Occupational Health, Imperial College Healthcare NHS Trust, London, UK. john.harrison@imperial.nhs.uk.
authors.forename: John
authors.initials: J
authors.lastname: Harrison
authors.affiliation: Department of Human Resources, Imperial College Healthcare NHS Trust, London, UK. penny.parker@imperial.nhs.uk.
authors.forename: Penny
authors.initials: P
authors.lastname: Parker
authors.affiliation: National Centre for Infection Prevention and Management and National Institute for Health Research Health Protection Research Unit in Healthcare Associated Infection and Antimicrobial Resistance Imperial College London, London, UK. alison.holmes@imperial.ac.uk.|Department of Infection Prevention and Control, Imperial College Healthcare NHS Trust, London, UK. alison.holmes@imperial.ac.uk.
authors.forename: Alison H
authors.initials: AH
authors.lastname: Holmes
mesh_terms: D000041:Absenteeism; D000293:Adolescent; D000328:Adult; D000465:Algorithms; D002959:Civil Defense / Q000592:standards*; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D010564:Personnel, Hospital / Q000706:statistics & numerical data*; D011320:Primary Health Care / Q000706:statistics & numerical data; D011446:Prospective Studies; D058996:Quality Improvement; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult