Figure 5.

The effect of household-level contact tracing on growth rates of simulated epidemics: tracing initiation and adherence. (a) Tracing initiated without waiting for a test result (initiated on symptom report for untraced cases, symptom onset for traced cases). (b) Positive test result required to initiate tracing. (c) Tracing initiated without waiting for a test result (initiated on symptom report for untraced cases), imperfect adherence to quarantine. For all simulations, household-level contact tracing was used. Two-step tracing was performed at the household level for 50% of simulations. Negative values on the doubling time axis imply a halving time and a declining epidemic for these values. The growth rate without contact tracing was derived by simulation of the branching process without contact tracing. (Online version in colour.)