In order to understand how influenza spreads in a population, Stanford University researchers created an interesting experiment involving an entire American high school. Everyone, including teachers, students, and staff were issued devices that relayed their live location to a central server continuously throughout the school day. The system provided researchers with a better understanding of how disease can spread based on which people were close enough to others, and the recorded database of these interactions can serve as a digital platform on which to simulate other contagious scenarios.
The devices logged more than 760,000 incidents when two people were within 10 feet of each other, roughly the maximum distance that a disease can be transmitted through a cough or sneeze.
After collecting the electronic tracking data, the researchers ran thousands of simulations of what would happen if there were a flu outbreak in the school.
They asked 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? Would it make sense to vaccinate the more popular students, thinking they might have more interactions than their classmates who keep to themselves? Or would it be best to vaccinate a random sample of the population?
They found it hardly matters whom you inoculate, unless you are certain of how people are interacting with others.
"Almost nothing was better than the random strategy unless you measure who interacts with who and for how long in a typical day," Salathé [Marcel Salathé, a former postdoctoral researcher at Stanford] said. "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."
The information gleaned from the high school experiment could be helpful in putting the brakes on the spread of flu in a place like a school, where outbreaks sometimes lead to the closure of an entire facility. But Salathé stresses that authorities must consider the medical, social and ethical ramifications of doing what they did – tracking the movements and whereabouts of an entire population – on a larger scale.
Abstract in PNAS: A high-resolution human contact network for infectious disease transmission
Press release: Stanford research follows spread of flu in high school…