structural:reformatting
Syndromic surveillance

A syndromic surveillance system based on search queries was first proposed by Gunther Eysenbach, who began work on such a system in 2004. Inspired by these early, encouraging experiences, Google launched Google Flu Trends in 2008. More flu-related searches are taken to indicate higher flu activity. The results, which were published in Nature, closely matched CDC data, and led it by 1–2 weeks. However, it has been shown that the original approach behind Google Flu Trends had various modelling deficiencies leading to significant errors in its estimates. More recently, a series of more advanced linear and nonlinear approaches to influenza modeling from Google search queries have been proposed. Extending Google's work researchers from the Intelligent Systems Laboratory (University of Bristol, UK) created Flu Detector; an online tool which based on Information Retrieval and Statistical Analysis methods uses the content of Twitter to nowcast flu rates in the UK.