Fig. 1

Schematic illustration of virus intrusion (A), disease progression (B) and the implementation of surveillance (C). \(S\): Susceptible, \(E\): Exposed, \({I}_{P}\): Presymptomatically Infectious, \({I}_{S}\): Symptomatically Infectious, \({I}_{A}\): Asysmptomatically Infectious, \(R\): Recovered. Panel C demonstrates symptom-based baseline surveillance in a hypothetical case scenario. Agent 1 has been infected outside of the clinic (index case) and infects agent 2, who goes on to infect agent 3 and 4. On day 6, agent 2 is isolated due to developing symptoms and once the case is ascertained a day later, contact tracing isolates the primary infector (backward tracing) and subsequent infections by agent 2 (forward tracing). The isolated individuals are then tested, confirming that agent 1 and agent 3 are infectious. Agent 4 is released as the infection is not yet detectable