Fig. 4: Effect of R0 and disease parameters on performance.
From: Bidirectional contact tracing could dramatically improve COVID-19 control
(top row) Mean Reff achieved and (bottom row) mean % of outbreaks controlled by different tracing strategies as a function of the basic reproduction number R0, assuming (left) median, (middle) optimistic or (right) pessimistic disease parameters (Table 1), assuming 50% ascertainment of symptomatic cases, 70% test sensitivity, 90% probability of trace success, a 6-day manual tracing window, and high (80%) smartphone coverage (Table 1). Error bars in the bottom row represent 95% credible intervals across 1000 runs under a uniform beta prior. Isolation on the basis of symptoms can dampen the outbreak at low R0, even in the absence of tracing.
