To Halt Infectious Diseases, Quarantine the Popular Kids

In the event of a pandemic outbreak of bird flu or the new MERS virus, public officials might want to look at quarantining children and teachers first—a new study has found that young people and school teachers are prime candidates to spread infection, due to the amount of "social contact" they have each day.

Anyone who has watched chicken pox spread through a classroom may think the study's findings are just common sense, but tracking disease as it moves through a population has been tough, especially with highly contagious, airborne infections like the flu.

The study, published in Proceedings of the Royal Society B, tracked the social interactions of about 5,000 British people. It found that average person had about 26 hours of contact with other people per day (when someone was in close contact with multiple people at once, the time with each person was counted). But some groups had much more contact than the average person, including children (47 hours), health workers (33 hours), people in the service industry (33 hours), and teachers (32 hours).

"There was a big hole in our knowledge about how people interact," Leon Danon, of the University of Warwick and lead author of the study, said. "We had to make a lot of assumptions about patterns of interactions and their networks that might facilitate infectious disease transmission. Now we've got a general overview about what social patterns are like."

Among the findings: As people age, they tend to have less social interaction, with the exception of parents, who have to take their kids on playdates and the like. Total contact hours peak when you are a toddler, with roughly 40 hours of "touching" social contact per day. That falls below 20 hours in your 20s before reaching a last-ditch peak of about 25 hours in your 40s. People in their 80s had, on average, less than 10 hours of social contact a day.

Teachers, students, transport workers, mechanics, and office workers had the most social interaction daily. These findings, Danon said, can help public health officials shut down disease once there's an outbreak by either quarantining certain people or administering prophylactic drugs to those groups first.

"This certainly helps tell us the people who we should be targeting. If we have a vaccine, that's great, but with a novel pandemic, the likelihood is there won't be a vaccine. The thing to do is to keep those people as far away from each other as possible," Danon said. "We can do things like closing schools in a pandemic setting so children have a lower number of social contacts."

Danon and his team are now working on studies to better understand how social networks work. While they now know how often people with certain jobs interact with others, they don't know exactly how those occupations are connected.

"We're limited now in that we only know statistics about single individuals. We don't know how they're linked together, how these things spread through the country. We're working on seeing how certain demographics interact," he said. "I think right now we're way behind highly infectious disease. With swine flu in the UK, we tried to do contact tracing, but because flu is so contagious, it just kind of escaped us."