Using social networks and smart phones to uncover the social determinants of respiratory infection transmission

Isolation of ill individuals is considered a key prevention measure for reducing disease transmission in community settings, yet few studies have examined isolation effects in community settings and none have experimentally tested this integral public health intervention. Here we describe the design, methods, study population characteristics, and social network structure of a randomized intervention for isolating respiratory infectious illness cases in a community setting. A total of 590 students in six residence halls on a university campus enrolled in the eX-FLU study during a chain-referral recruitment process from September 2012-January 2013. Of these 590 individuals, 262 joined as “seed” participants, who then nominated their social contacts to join the study, of which 328 “nominees” enrolled. 117 residence hall clusters of participants were randomized to either a three-day isolation intervention group or a control group. Participants were asked to respond to weekly surveys on health behaviors, social interactions, and influenza-like illness (ILI) symptoms. Following ILI onset, participants in the intervention group were asked to isolate themselves in their dorm room for three days. ILI cases reported on their isolation behavior during illness and provided throat and nasal swab specimens at illness onset, day-three, and day-six of illness. A subsample of individuals (N=103) also participated in a sub-study of a novel smartphone application, iEpi, which collected sensor and contextually-dependent survey data about participants’ social interactions. Within the social network, participants were significantly positively assortative by a range of characteristics, including intervention group, residence hall/house, iEpi participation, parental education, employment status, risk for complications due to influenza, and smoking/drinking habits (all P<0.05). The design of this social network intervention study and 10-week longitudinal follow-up provides an unparalleled opportunity to address questions about social networks, isolation and infection transmission, and provides insights into social characteristics, behaviors, and perceptions among college-aged students.