GOOGLE DISEASE TRENDS: AN UPDATE

The purpose of Google Flu Trends (GFT) is to use search keyword trends from Google.com to produce a daily estimate, or nowcast, of the occurrence of flu two weeks in advance of publication of official surveillance data. While not covered in detail in this paper, Google Dengue Trends, launched in June 2011, is a service that uses similar techniques to track Dengue fever. During the 2012 flu season we observed our algorithm overestimating influenza-like illness (ILI). We have concluded that our algorithm for Flu and Dengue were susceptible to heightened media coverage and have since developed several improvements.