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Google just launched an updated version of Google Flu Trends, a service that predicts flu trends by tracking flu-related queries on the company's search engine. Until now, Google only showed aggregate data for states in the United States. Starting today, Flu Trends will show data down to the city level for 121 cities. As Google notes in today's announcement, this update was timed to coincide with National Influenza Vaccination Week.

Last month, we told you about Google's Flu Trends' expansion to 20 countries around the world. The program monitors mentions of flu symptoms to predict - and hopefulyl help prevent - flu outbreaks.

Today, Google has announced a new feature of Maps that will allow users to find flu vaccines near them. In partnership with the U.S. Department of Health and Human Services, the American Lung Associaltion, and Flu.gov, Google Maps is now helping users search for seasonal flu vaccination locations, H1N1 flu shots, or both together.

Google just launched an experimental version of Flu Trends that focuses only on the current flu outbreak in Mexico. Google Flu Trends, which was launched last November, tracks and maps flu-related search queries to predict how many people in a given region actually have the flu. Google stresses that Flu Trends for Mexico is only an experimental product, and that it tries to distinguish between topical searches about the flu and searches by users who may actual experience flu symptoms. Given the current interest in the swine flu, a lot of users are obviously looking for general information about it, which could easily skew Google's algorithms.

It stands to reason that people who are "starting to come down with something" often take the opportunity to search for information on what ails them, even before they discuss their symptoms with a healthcare professional. Who gets more of those searches than anyone? Google, of course.

When Google started looking more closely at anonymous aggregate searches for "flu symptoms" and the like, they discovered that - after cross-referencing that data against information from the Center for Disease Control - they had the ability to predict flu outbreaks by monitoring search patterns. And now, they've published their findings as Google Flu Trends.