Fig. 3: Bidirectional tracing under reduced ascertainment and test sensitivity.
From: Bidirectional contact tracing could dramatically improve COVID-19 control
a Mean Reff achieved by different tracing strategies as a function of the percentage of symptomatic cases that can be identified by health authorities on the basis of symptoms alone, assuming 70% test sensitivity. b Mean Reff achieved by different tracing strategies as a function of test sensitivity, assuming 50% ascertainment of symptomatic cases. c As in (b), but allowing contact tracing to be initiated from symptomatic cases on the basis of symptoms alone (i.e., without a positive test result). All panels assume 90% probability of trace success, a 6-day manual tracing window, high (80%) smartphone coverage, and median disease parameters (Table 1). Isolation on the basis of symptoms can dampen the outbreak even in the absence of tracing.
