Google's philanthropic tentacle, google.org, has found a strong correlation between official data on influenza from the Center for Disease Control and Prevention and the number of people searching for flu information on google.com.
Google Trends collects the 100 most popular searches on Google.com. Many of these entries reflect last night's TV or enduring internet interests like escort girls or obscure anime cartoons. By stripping out such distractions some interesting information remains - at the time of writing flu symptoms were the most popular US search. At number two however is "insomnia cookies". The service is used by marketeers to judge the impact of campaigns on web searchers.
The surprising thing is that Google's information can be as much as two weeks ahead of CDC data. Researchers looked at certain flu-related search terms for the last five years and compared them to flu surveillance information from CDC. They found CDC data, collected from doctors and hospitals, followed Google Trends by about two weeks. Almost every increase in numbers of flu cases was preceded by an increase in flu searches.
Over the 2007-2008 flu season Google shared this information with the CDC and was "able to accurately estimate current flu levels one to two weeks faster than published CDC reports". The service is so far only available in the US but allows you to search by state.
CDC data from doctors and hospitals take a while to collect and analyse while Google's search terms can be crunched much more quickly.
The research has now been accepted in principle for publication in Nature. Google hopes the data will allow doctors and health planners to respond more quickly to epidemics or even pandemics.
More on flu trends from Google.org. ®