Temporal Connectivity of Social Contact Networks in Urban and Rural India

Background The epidemic potential of infectious diseases depends on how contacts connect individuals over time—a form of temporal connectivity that has rarely been quantified in resource-poor settings. We used the forward-reachable path (FRP)—the proportion of population reachable from an index person via direct or indirect connections—to quantify temporal connectivity in contact networks relevant for acute respiratory transmission. Methods From empirical social-contact data collected in rural and urban Tamil Nadu, India, we derived contact-location–specific network statistics. These statistics were used to parameterize dynamic network models, simulate daily networks over one year, and compute FRPs. Results In both rural and urban networks, mean FRPs rose sharply on day 1, then either increased steadily at school and work or plateaued at home and at locations included in the other layer (that is, locations other than home, school, and work). By day 365, mean FRPs followed the order: home (0.06% [rural] and 0.03% [urban]) < school (11.96% [rural] and 9.14% [urban]) < work (12.55% [rural] and 26.72% [urban]) < other (40.54% [rural] and 67.99% [urban]). The mean FRP peaked at home among those aged ≥60 years, at school among those aged 10–19 years, and at work among those aged 40–59 years. Conclusions Although FRP at home was bounded by household size, reachability expanded substantially through school, work, and other contacts. These findings indicate high temporal connectivity and substantial epidemic potential for acute respiratory transmission in these settings.