Seasonal flu epidemics account for as many as half a million deaths worldwide each year. And the rapid spread of new strains can cause many more (the 2009 H1N1 flu pandemic alone killed more than 16,000 people, according to the World Health Organization). Quickly detecting a regional rise in flu-like symptoms such as coughs, sore throats or high fevers can help public health officials take steps to dampen the impact. However, it can take days—even weeks—for trends spotted in clinics to be reported more broadly.

Before visiting a clinic, many flu sufferers visit Web sites for information about symptoms and remedies—a tendency that Google engineers took advantage of to create a real-time flu tracker called ‘Google Flu Trends.’

"We're constantly looking for trends in our search results, and ways to use them to do something useful," says Jamie Yood, communications lead for Google Flu Trends.

By comparing the popularity of the 50 million most common Google search queries in the U.S. with flu-like illness rates measured by the U.S. Centers for Disease Control and Prevention's (CDC) national surveillance program, the Flu Trends team narrowed down the pool to 45 search terms (relating to symptoms, complications and remedies) that correlated with the agency's data on the prevalence of flu symptoms. "It shows the trends—whether flu-like illness rates are going up or down in certain regions," says Yood.

"Oscar nominations" and "March madness" queries also peaked during flu season, but didn't make the cut, Yood jokes.

The CDC's national surveillance program is based on weekly reports from 3,000 health clinics that count the number of patients with a fever and a cough or a sore throat. But it takes up to two weeks for these numbers to be compiled into meaningful and publicly available information about flu trends, Yood says. Google Flu Trends is updated daily, and according to data from the 2007–2008 flu season, it can bridge the CDC's two-week lag, potentially buying officials critical extra time to devise a public health response and curtail the virus's spread.

Google collaborated with the CDC to validate the flu tracker. "They were really excited about the idea of having another source of information that could help with early detection," Yood says of the agency. Together, Google and the CDC published their search query–based flu-tracking model in Nature in February 2009.

8 Comments

1. 1. David N'Gog 10:09 AM 5/17/10

   If Google can map flu trends- makes you wonder what else they can track... and you can bet any authoritarian government would love to have access to google's data to manage their country.
   
   Wonder if google could beat out the exit polls in predicting election results based on peoples searches.
   
   "Healthcare" democrat voter.
   "Military" republican voter.
   "Where to buy pot" libertarian voter.

   Reply | Report Abuse | Link to this

2. 2. agenthucky in reply to David N'Gog 11:57 AM 5/17/10

   This is why Google said NO to China

   Reply | Report Abuse | Link to this

3. 3. hellblade in reply to David N'Gog 12:43 PM 5/17/10

   data from google trends is available to anyone with an internet connection, not just google. since the information is open, there should be no need to worry about authoritarianism.

   Reply | Report Abuse | Link to this

4. 4. jhu169 01:03 PM 5/17/10

   "Before visiting a clinic, many flu sufferers visit Web sites for information about symptoms and remedies"
   
   This is an important assumption for the usefulness of Google Trend. Is there any evidence shows that people visiting internet BEFORE they go to doctors? I can see the major peaks of Google Trend are always a little behind the peaks of CDC data, suggesting people visit websites AFTER hearing CDC warnings from news or other resources.

   Reply | Report Abuse | Link to this

5. 5. m 07:05 AM 5/18/10

   Well

   Reply | Report Abuse | Link to this

6. 6. m 07:09 AM 5/18/10

   The merits of "this" are so extreme its hard not appreciate that the CDC were excited.
   
   Take for instance the death flu...everyone dies from it after 36 hours...with the internet google feature assuming the tracking system actually worked the death flu would be halted before and this is a guess more than 40% of the population had been infected and killed. Sure most of the world would be dead and the people on the TV explaining what to do would be dead people walking...but for those people who hadnt gone shopping in the last 3 days would be alive and well.
   
   

   Reply | Report Abuse | Link to this

7. 7. ekeyme in reply to agenthucky 07:28 PM 5/20/10

   Ahh, maybe China may take the flu rate as a country secret or Google was not welcome in Chinese official media so Google hard to get the data.

   Reply | Report Abuse | Link to this

8. 8. web bhai 09:02 AM 6/9/10

   may be if you want to,make more web information,about alexa rank,ip look up,TLDs and DNS look up www.websitelog.net...that is the good website....

   Reply | Report Abuse | Link to this