Flutracking and Pandemic (H1N1) 2009 | CDC EID

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Volume 16, Number 12–December 2010
Dispatch
Online Flutracking Survey of Influenza-like Illness during Pandemic (H1N1) 2009, Australia


Sandra J. Carlson, Craig B. Dalton, David N. Durrheim, Comments to Author and John Fejsa
Author affiliations: Hunter Medical Research Institute, Wallsend, New South Wales, Australia (S.J. Carlson, C.B. Dalton, D.N. Durrheim); Hunter New England Population Health, Newcastle, New South Wales, Australia (S.J. Carlson, C.B. Dalton, D.N. Durrheim, J. Fejsa); and Newcastle University, Newcastle (C.B. Dalton, D.N. Durrheim)

Suggested citation for this article

Abstract
We compared the accuracy of online data obtained from the Flutracking surveillance system during pandemic (H1N1) 2009 in Australia with data from other influenza surveillance systems. Flutracking accurately identified peak influenza activity timing and community influenza-like illness activity and was significantly less biased by treatment-seeking behavior and laboratory testing protocols than other systems.

A variety of surveillance methods were used to monitor the incidence and severity of influenza A pandemic (H1N1) 2009 in Australia. Severity of illness was measured by number of hospitalizations, intensive care unit (ICU) admissions, and deaths. Influenza disease incidence was monitored through laboratory-confirmed cases, general practitioner sentinel surveillance of influenza-like illness (ILI), emergency department visits for ILI, absenteeism data from large employers, and the Flutracking surveillance system (1).

Flutracking is a national weekly online survey of ILI (completed by >8,000 participating community members each week in 2009); it is the only ILI surveillance system that provides comparable data across Australia's states and territories. Flutracking integrates participants' ILI symptom information with their influenza vaccination status (2). Flutracking surveillance has correlated well with other Australian influenza surveillance systems in describing the timing and scale of the 2007 and 2008 seasonal influenza epidemics (3,4). We compared Flutracking data with data from other routine influenza surveillance systems during the 2009 pandemic wave in New South Wales (NSW), Australia's most populous state.
The Study

From May 4, 2009, through October 31, 2010, participants received an automatically generated weekly email link to the online questionnaire, which asked whether they had experienced fever or cough and how many days they had been absent from work or normal duties because of these signs (recruitment details in 2,3; location of participants at www.flutracking.net). Each individual response usually took <15 seconds. Participants who had previously reported not receiving seasonal influenza vaccine were asked whether they had received influenza vaccination in the prior week during each weekly survey. If they answered yes, the question was automatically deleted from their subsequent weekly surveys. Participants were permitted to enroll at any time during the surveillance period. Participants could respond on behalf of household members, and children >12 years of age could complete their own survey. During online enrollment, participants provided the following information: their month and year of birth; whether they had received a seasonal influenza vaccine in the preceding year; whether they worked face to face with patients in hospitals, nursing homes, doctors' clinics, or as community health workers; and their residential postal code.

The weekly proportion of participants with ILI signs or symptoms was calculated as the proportion of participants for that week who reported both fever and cough within the previous 7 days. These proportions were compared with influenza activity recorded in 2009 by other established New South Wales influenza surveillance systems, i.e., number of patients who visited emergency departments with ILI symptoms (5), laboratory-confirmed influenza A antigen tests (PCR and direct immunofluorescence) (5), Google Flu Trends data (aggregated Google search data used to estimate current influenza in Australia) (6), workplace absenteeism data (5), and Australian Sentinel Practice Research Network (ASPREN) general practice ILI data (7).

Surveillance data were compared with data from 2007 and 2008. NSW was selected because no other states had sufficient Flutracking participants in 2007 and 2008 to allow year-to-year comparisons. The number of NSW participants who completed >1 survey in the 2009 Flutracking surveillance system was 3,447.

The concordance across NSW influenza surveillance systems was high for ILI peak weeks during the past 3 years. During 2009, Flutracking, laboratory influenza notifications, and Google Flu Trends peaked 1 week before emergency department ILI, workplace absenteeism, and ASPREN ILI surveillance (Table).

full-text:
Flutracking and Pandemic (H1N1) 2009 | CDC EID


Suggested Citation for this Article

Carlson SJ, Dalton C, Durrheim DN, Fejsa J. Online Flutracking survey of influenza-like illness during pandemic (H1N1) 2009, Australia. Emerg Infect Dis [serial on the Internet]. 2010 Dec [date cited]. http://www.cdc.gov/EID/content/16/12/1960.htm

DOI: 10.3201/eid1612.100935

Comments to the Authors

Please use the form below to submit correspondence to the authors or contact them at the following address:

David N. Durrheim, Locked Bag 10, Hunter Medical Research Institute, Wallsend, New South Wales 2287, Australia; email: david.durrheim@hnehealth.nsw.gov.au