Health Inc.

Google's Flu Early Warning System

Our Flu Shots blog has been humming along for about a week now and somehow failed to mention Google's Flu Trends website. This post addresses that oversight.

What's Google Flu Trends, you ask? It's Google's attempt to provide something of an early-warning system on flu outbreaks by analyzing search terms it believes people would most likely search on when flu is a lively presence in their households, schools, workplaces etc.

According to Google and a scientific paper recently published in Nature, there's an extremely high correlation, better than 90 percent and, in some instances, much better than that, between certain search terms and the Centers for Disease Control and Prevention's surveillance data. (Five of the paper's six authors worked for Google at the time of publication, by the way. The one non-Google person was at the CDC.)

The advantage of using the search data is that it flows in significantly faster than the surveillance data, perhaps with a lag of only a day compared with surveillance data where the lag can be more like one to two weeks. The advantages to public health officials of having such data earlier are self-evident.

NPR has actually reported on Google Flu Trends. It was featured on Talk of the Nation last year, for instance.

Anyway, it's a fascinating idea that a flu outbreak could be tracked by analyzing search-engine queries.

Google started an experimental Mexico flu tracker for the swine flu outbreak. Compared with its U.S. flu tracker, its Mexican version inspires less confidence from Google.

As Google explains on its blog:

In response to recent inquiries from public health officials, we've been attempting to use Google search activity in Mexico to help track human swine flu levels. Experimental Flu Trends for Mexico is, as you might have guessed, very experimental. But the system has detected increases in flu-related searches in Mexico City (Distrito Federal) and a few other Mexican states in recent days, beginning early in the week of April 19-25.

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.

While we would prefer to validate this data and improve its accuracy, we decided to release an early version today so that it might help public health officials and concerned individuals get an up-to-date picture of the ongoing swine flu outbreak. As with our existing Flu Trends system, estimates are provided across many of Mexico's states and updated every day. Our current estimates of flu activity in the U.S. are still generally low as would be expected given the relatively low confirmed swine flu case count. However, we'll be keeping an eye on the data to look for any spike in activity.

Just more evidence of Google's plan for world dominion.

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