CovidSIMVL - Agent-Based Modeling of Localized Transmission within a Heterogeneous Array of Locations: Motivation, Configuration and Calibration

Moselle, K. A.; Chang, E.

CovidSIMVL is an agent-based infectious disease modeling tool that is designed specifically to simulate localized spread of infectious disease. It is intended to support tactical decision-making around localized/staged re-institution of pre-pandemic levels and patterns of social/economic/health service delivery activity, following an initial stage of pan-societal closures of social/economic institutions and reductions in services. By design, CovidSIMVL supports the generation of dynamic models that reflect heterogeneity within and between an array of interacting localized contexts. Within a localized context (a CovidSIMVL "Universe"), this heterogeneity is embodied in a hierarchically-organized array of rules that reflect the pathophysiology of transmission, the role of physical proximity in infection transmission ("HazardRadius" in CovidSIMVL),and the movement of people within a localized setting ("MingleFactor"). Within an interacting array of localized contexts (a CovidSIMVL "Multiverse"), this heterogeneity is embodied in different patterns of movement of agents between different contexts. To calibrate the HazardRadius and MingleFactor parameters, growth curves were generated with CovidSIMVL by setting different configurations of values on those two factors. These were compared to the characteristic shape of curves generated by equation-based compartmental models (e.g., SEIR models) that fit different real-world datasets that embody different reproduction numbers (R0). By operating with parameter values in CovidSIMVL that generate "real-world" growth curves, the tool can be used to produce plausible simulations of localized chains of transmission, including cross-over transmission among impacted/unaffected contexts or sub-populations, via agents who interact within and across arrays of local contexts, such as schools, multigenerational families, recreational facilities, places of work, or other settings in which people are in close physical proximity.