Tracking The Real-Time Spread Of The Flu

An entire high school population was tracked in real-time to learn how infectious disease spreads.

Cold and flu season is upon us, and with every social interaction there’s a sneaking suspicion that the person sneezing during the morning commute or coughing at the desk beside you could make you ill. In order to understand how influenza spreads in a population, James Holland Jones of Stanford University’s Woods Institute for the Environment and colleague Marcel Salathé conducted an interesting experiment involving an entire high school throughout one day during the height of last January’s swine flu outbreak.

Each student, teacher, and staff member were outfitted with credit-card sized sensors that transmitted and received radio signals every 20 seconds. The device also relayed their live location to a central server continuously throughout the school day, providing researchers with a better understanding of how disease can spread based on which people were close enough to others. The devices recorded 760,000 instances when two people were within 10 feet of each other, approximately the maximum distance that a disease can be transmitted through a cough or sneeze.

After the collection of tracking data, the researchers ran thousands of simulations asking questions like: “What would happen if there were enough of a vaccine to inoculate only a fraction of the school’s population. Would it be better to vaccinate teachers or students?” The researchers discovered that it doesn’t matter who you vaccinate, unless you are certain of how people are interacting with others. Marcel Salathé explains the outcome of the research:

Almost nothing was better than the random strategy unless you measure who interacts with who and for how long in a typical day. That flies in the face of what most people might think – that the super-popular kids with more connections than everyone else are more likely to spread more of the virus. But it doesn’t matter if you’re a teacher or a student or a staff member, or whether you’re popular or not. Everyone’s pretty much the same when it comes to transmission of the flu.

Stanford University News

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