Have you used Google to search for cold symptoms, or a home remedy? Then you’ve unwittingly helped the search giant to predict the outbreak of flu on an international scale.

    You’re definitely going to get the flu this year.

    Alright, sorry, maybe not definitely. But as the CDC is reporting, the flu season is off to an “early start,” and will likely be one of the worst in the past decade.

    But how does the CDC predict such things? With cold, hard clinical evidence: the organization publishes a weekly FluView report based on the number of patients who have reported flu-like symptoms and the number of hospitalizations. But as CDC Director Thomas Frieden noted, the spread of the flu is fairly “unpredictable,” and FluView has a one- to two-week lag.

    Leave it to Google to leverage our search data to create an almost real-time prediction map. “In 2007, a small team of engineers began to explore ways of accurately modeling real-world phenomena using patterns in search queries,” Corrie Conrad, a Senior Program Manager at Google, tells Co.Design. “We found that what people search for is actually a good indicator of influenza activity in a population.” The resulting Google.org app, Google Flu Trends, tracks the number of times that users search for flu information, like ”flu symptoms” or “flu remedy). Then, each search is added to the map using the IP address associated with the query, creating a hyper-local map that predicts outbreaks in near real-time. It’s essentially a map that uses the Google Trends to predict illness. “While traditional systems require 1-2 weeks to gather and process surveillance data, our estimates are current each day,” explain the team in a piece in the journal Nature (PDF here).

    “Of course, not every person who searches for ‘flu’ is actually sick, but a pattern emerges when all the flu-related search queries are added together,” explain the designers. “We compared our query counts with traditional flu surveillance systems and found that many search queries tend to be popular exactly when flu season is happening.” This year, the Google team co-authored a paper with a CDC researcher proving that the Flu Trends data is closely correlated with an increase in emergency room activity, in general.

    Could Google Trends emerge as an ally for hospitals struggling during times of epidemics and pandemics? Despite the privacy qualms many have about Google, it’s a remarkable idea. Conrad tells Co.Design that they have no current plans to expand the methodology to more diseases, but they’ve found that their system is also accurate in predicting Dengue. It’s interesting to imagine how the methodology could be applied to more general trends–birth rates, for example, or even mental health issues. One Finnish data junkie, for example, has used the data to compare it to sick days taken. It correlates. . . roughly.

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