How severe was the 2015 influenza season in Australia?
The answer depends on how much and which data one consults
Media coverage of the 2015 influenza season in Australia depicted a severe influenza season, focusing on the record number of laboratory-confirmed influenza cases notified to health authorities.1,2 We used sentinel surveillance data and a weekly online symptoms survey to compare the magnitude of the 2015 influenza season in Australia with recent seasons.
Data were provided by the Australian Sentinel Practices Research Network (ASPREN), the Victorian Sentinel Practice Influenza Network (VicSPIN) and the Sentinel Practitioners Network of Western Australia (SPNWA). Together, these networks conduct Australia-wide surveillance of influenza-like illness (ILI; defined as cough, fever and fatigue). Participating general practitioners submit weekly reports on the number of patients presenting with ILI and the total number of consultations. Influenza polymerase chain reaction (PCR) test results of nose and throat swabs from ILI patients collated by ASPREN (a 20% systematic sample) and VicSPIN (selected at the discretion of the GP) were also available. Data were also provided by Flutracking, a national, weekly online survey of volunteers that can estimate the proportion of participants with ILI (defined as cough and fever, and/or the absence from normal duties). Notifications data are publicly…