Figure 1:

Transmission model structure. Compartments represent health states, with transitions between health states in a stable population of fixed size. A proportion of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) develop severe coronavirus disease 2019 (COVID-19) and require admission to hospital. Among individuals with nonsevere COVID-19, a proportion self-isolate after receiving a diagnosis of confirmed or syndromic COVID-19 or may self-isolate without a diagnosis; the remainder do not self-isolate. Only a subset of individuals with nonsevere COVID-19 receive a confirmed diagnosis if they undergo testing. Individuals in the infectious health states may pass the virus on to others. We assume that individuals in self-isolation or hospital-isolation cannot pass on the virus, but superspreading events are included to capture community, long-term care and nosocomial (hospital-acquired) clusters of transmission events. Note: ICU = intensive care unit.