Mob Behavior and Medicine

Google Flu Trends , from Google.org ,  the philanthropic arm of Google, is a free online tool that may allow you to detect flu outbreaks in your area up to two weeks before official reports from the CDC .

Here's how it works: Millions of users enter health-related search terms in Google. During the flu season, many of these terms are flu-related. By tracking this aggregated search data, Google is able to estimate flu activity within a state earlier than the CDC's official reports appear. See the little video at Google.org for an illustration of this phenomenon.

The CDC's reports are based on information from health providers. Google searches usually occur before a person goes to a health professional, so in terms of reporting, Google's aggregated data cuts out the middle person, as it were. The graph below "shows five years of query-based flu estimates for the Mid-Atlantic region of the United States, compared against influenza surveillance data provided by CDC's U.S. Influenza Sentinel Provider Surveillance Network. As you can see, estimates based on Google search queries about flu are very closely matched to a flu activity indicator used by CDC" (Google.org):

Google warns that past behavior does not necessarily predict future success in forecasting flu trends. Google Flu Trends is still experimental, but it has a great deal of promise as Google continues to tinker with it. It may, for instance, be a useful tool as epidemiologists attempt to identify and contain flu pandemics, such as the outbreak of 1918.

You can read more about Google Flu Trends at

• The New York Times 
• The Official Google.org Blog