Estimating modern US social contact patterns, the ENGAGED study: a study protocol for a staggered longitudinal cohort study

Introduction Accurately capturing social contact data is essential for developing effective mathematical models to forecast disease trends and evaluate interventions. There are limited population-based data of social contacts in the USA which limits our ability to accurately model infectious disease transmission.

Methods and analysis To fill in this gap, we conducted a staggered longitudinal cohort study in metropolitan Atlanta, Georgia, USA. We aimed to characterise contact patterns and examine how they varied by (1) participant demographics, (2) seasonality and (3) self-managed and medically-attended symptoms.

Once per month for 6 months, participants reported individual contacts they can name, individual contacts they cannot name and contacts that occurred in group settings. We defined individual contacts as a two-way conversation with five or more words in the physical presence of another person or physical skin-to-skin contact and group contacts as contacts with a group of people with whom participants talked, interacted or shared space.

Participants were enrolled on a rolling basis, and data is collected from November 2024 through April 2026.