Besides bringing a white Christmas, the cold winter also brings along a flu season to the northern atmosphere. The number of patients who have reported flu-like symptoms and the number of hospitalizations will drastically increase during this season. The spread of flu is fairly unpredictable and requires 1 - 2 weeks for data gathering and processing before publishing the trend.
Now, Google has a way to predict flu trend in real-time. A team of Google's engineers were using internet search pattern to predict flu trend. They track the number of times that users search for flu-related information. Google found a close relationship between how many people search for flu-related topics and how many people actually have flu symptoms. When compare to the traditional flu surveillance systems they actually match well.
For more info visit: http://www.google.org/flutrends/intl/en_us/