  Individuals involved in common group activities/settings -- e.g., college
students that are enrolled in the same class and/or live in the same dorm --
are exposed to recurrent contacts of physical proximity. These contacts are
known to mediate the spread of an infectious disease, however, it is not
obvious how the properties of the spreading process are determined by the
structure of and the interrelation among the group settings that are at the
root of those recurrent interactions. Here, we show that reshaping the
organization of groups within a population can be used as an effective strategy
to decrease the severity of an epidemic. Specifically, we show that when group
structures are sufficiently correlated -- e.g., the likelihood for two students
living in the same dorm to attend the same class is sufficiently high --
outbreaks are longer but milder than for uncorrelated group structures. Also,
we show that the effectiveness of interventions for disease containment
increases as the correlation among group structures increases. We demonstrate
the practical relevance of our findings by taking advantage of data about
housing and attendance of students at the Indiana University campus in
Bloomington. By appropriately optimizing the assignment of students to dorms
based on their enrollment, we are able to observe a two- to five-fold reduction
in the severity of simulated epidemic processes.
