To quote the Google.org blog:
In November 2008 we launched Google Flu Trends after finding a close relationship between how many people search for flu-related topics and how many people actually have flu symptoms. Google Flu Trends may be able to detect influenza outbreaks earlier than other systems because it estimates flu activity in near real time.This is a way to use actual information, not tainted by politics, to form an idea of seriousness of the Swine Flu outbreak. Google explains how it attempts to validate the information:
In the United States, we were able to validate our estimates using data from a surveillance system managed by the U.S. Centers for Disease Control and Prevention (CDC). We have not verified our data for Mexico in the same manner, but we've seen that Google users in Mexico (and around the world) also search for many flu-related topics when they have flu-like symptoms. Given the tremendous recent attention to swine flu, our model tries to filter out search queries that are more likely associated with topical searches rather than searches by those who may be experiencing symptoms.Looking at the maps it is evident that flu activity is low in both Mexico and the U.S. However, there are areas of Mexico where the activity is moderate. None of these areas of higher incidence are those being mentioned in news accounts.
As Google notes:
To explore Google Flu Trends data, you can download files containing weekly influenza-like illness (ILI) estimates for the United States. Data is provided for each individual state, the nine influenza surveillance regions, and the entire United States. It is provided at the state level for Mexican states where we were able to produce more reliable estimates given a limited amount of time. Exported data may be used for any purpose, subject to the Google Terms of Service. If you choose to use the information, please make sure to appropriately attribute it to Google.