Social networks illustrate how disease can spread

NEW YORK (Reuters Health) - The best way to stop the next influenza pandemic in its tracks could be to shut down schools and keep students at home, according to the authors of a new study of social contact networks.

Based on the way they interact with one another, high school students “may form the local transmission backbone of the next pandemic,” Dr. Robert J. Glass of Sandia National Laboratories in Albuquerque, New Mexico, and his daughter, Laura M. Glass, suggest.

Networks for an entire community must be created to fully understand how to contain a potential epidemic, the senior Glass added in an interview. “With that kind of understanding you can then ask questions about where to target interventions,” he explained.

To develop the network described in the current study, the researchers surveyed elementary, middle and high school students about how and with whom they spent their time. Each person’s social network was characterized by the groups to which he or she belonged (such as the household, a class, or a sports team) along with the smaller network of person-to-person contacts within each of these groups.

The researchers then gathered information on the size of these groups, how many people a person was connected to within it, the amount of time he or she spent in the group, and the closeness of the contact a person had with individuals in that group.

They then evaluated the flu transmission potential of various contacts based on the degree of closeness and how much time a person spent in those contact activities.

Households, classes, groups of friends and sports teams all represented networks with “high potential for the transmission of influenza,” the researchers found. The older a child was, the more important outside connections became, with 75 percent of those in high school having social contacts outside the home conducive for transmitting influenza.

If it turns out that young people are a key route of influenza transmission within a community, closing schools and keeping children at home could help to shut down an epidemic, the researchers say. However, they add, similar studies in other groups within the community must be done to understand the other ways that the disease might spread.

“There are a whole bunch of things that you can learn from doing this kind of thing,” Glass noted. Networks can not only be used to study the spread of other types of disease, he added, but could also be used to identify individuals who are at-risk because they are less connected than others.

SOURCE: BMC Public Health, online February 14, 2008.