Fig. 1.

Compartment model. The progression of disease states in the extended SEIR network model is represented by the compartments shown. Susceptible (S) individuals become infected (exposed) following transmissive contact with an infectious individual. Newly exposed (E) individuals undergo a latent period, during which time they are infected but not contagious. Infected individuals then progress to a presymptomatic infectious state (${\mathit{\text{I}}}_{\text{pre}}$), in which they are contagious but not yet presenting symptoms. Some infectious individuals go on to develop symptoms (${\mathit{\text{I}}}_{\text{sym}}$), while others will remain asymptomatic (${\mathit{\text{I}}}_{\text{asym}}$). At the conclusion of the infectious period, infected individuals enter the recovered state (R) and are no longer contagious or susceptible to infection. The unshaded compartments represent quarantined individuals in the respective disease states. Individuals are moved into a quarantine compartment upon isolation due to symptoms or a positive test (gray arrows).