The public health advice that gets trotted out when a flu pandemic threatens is avoid too much direct contact with people, stay away from crowded public spaces, and stay home if you have symptoms to avoid spreading them. Now Stanford researchers have gathered hard data on the phenomenon by using portable Wi-Fi devices to work out how often flu could be communicated in one hardcore disease vector: a school.
The entire population of a U.S. high school, from staff to teachers to kids, were outfitted with portable IEEE 802.15.4 Telos B devices that had been programmed to detect when another device was within 10 feet (roughly the maximum distance across which a cough or sneeze can transmit the flu virus) every 20 seconds.
By measuring the number of proximity events in a typical January flu-season day, the Stanford team created a detailed map of the school’s “human contact network”–essentially a physical human social network for infectious disease transmission. The number of close proximity interactions (CPIs) reached an astonishing 762,868 meetings among just 788 people. That means in the course of just one school day there were at least three quarters of a million chances for a bug to transmit itself from one person to another.
The team then used this map of the school’s social network to model how a real flu outbreak would spread, under a number of scenarios including vaccinating a small group of students or staff (as may happen in real life), vaccinating the most social students, or a random group.
The answer is interesting: People were meeting so frequently that no vaccination strategy made a bigger difference than any other. The only way vaccination would significantly affect the spread of the disease was if many of the students, rather than a few, got the jabs. Swiftly going home if you were ill was also a good way to prevent the spread of the flu, helping prevent secondary infections in 68% of the simulations the team ran.
What can we learn from this? First, if you get sick at work or school, don’t ever tough it out. Go home and prevent everyone else getting ill. This fact will hold true in every scenario. Also, tell people you’ve got flu using Facebook or Twitter, and they’ll know not to come near you. Other research is suggesting that Facebook and Twitter may become handy tools to prevent pandemics when virulent outbreaks occur. Finally, trying to design a vaccination strategy is not as straightforward as you may think–it’s simplest to vaccinate as many people as possible, even if this doesn’t seem economically sensible.
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