YOU MIGHT NOT THINK OF INTERNET
oversharing as a lifesaving habit, but maybe it is. For more than a decade, epidemiologists and data scientists have scanned our search-engine queries and social-media posts with the goal of discerning who is infected, what they have, and where they live. But deriving meaning from our consultations with Dr. Google faces an ironic obstacle: For all our copious snaps, selfies, and status updates, we’re just not sharing enough to consistently forecast disease outbreaks—including the flu.
Of course, influenza’s reign of terror started long before the birth of our modern social networks. A hundred years ago, the infamous “Spanish flu” spread rapidly around the world, infecting a third of the population and killing at least 50 million people. With the rapid evolution of the virus, and increasing international travel and urbanization enabling the quick spread of illnesses, a modern version of that pandemic could cause twice as many casualties, along with widespread disruption to the global supply of food, medicine, and energy. It doesn’t matter where you live or what you do. The flu could infect you.
Even in the absence of Flumageddon, improving our ability to forecast the illness is vital. Influenza viruses kill up to 646,000 people worldwide every year, including as many as 56,000 people in the U.S. Americans pay as much as $5.8 billion in medical care annually to fight the pestilence. If we know when it’s coming, health agencies could push people to get vaccinated. Hospitals could plan ahead.
Augmenting official flu reports from the Centers for Disease Control and Prevention (CDC) with data harvested from the internet is another step in our online evolution. According to a 2012 Pew Research Center study, about 184 million Americans (more than half the nation’s residents) use the Web to find healthrelated information. These searches are like tips to a crime hotline, enabling researchers to identify suspected flu cases. In 2006, Gunther Eysenbach, associate professor of public health at the University of Toronto, found that searches for the terms “flu” or “flu symptoms” spiked a week before a jump in doctor visits. “The internet has made measurable what was previously immeasurable,” he wrote in 2006, christening the new field “infodemiology.”
In 2008, Google rolled out Flu Trends, harnessing its own big data to look for worldwide flu surges and hot spots through symptom searches in 29 countries. Google scrapped the program in 2014—because of at least one factor that researchers hadn’t counted on.
Your search history, it turns out, can be misleading. It’s impossible for data collectors to know whether you were looking up “headache and fever” for yourself, or because you heard your co-worker complaining about their kid’s symptoms. In 2007, Americans suddenly started Googling “cholera”—had a new epidemic taken hold? Nope. Oprah Winfrey had just recommended Love in the Time of Cholera for her book club. “You should have seen what happened when Brad Pitt had viral meningitis,” says Lone Simonsen, professor of epidemiology at Roskilde University.
After culling search data from public resources, researchers run them through