For the computation, we first subtracted m¯, the integral of E(c(t)), by the integral of h(t), assuming that all cases h(t) were already traced, and then we multiplied the difference by 0.9, 0.7, or 0.5 if only 10%, 30%, or 50% of contacts were traced, respectively. For m, we accounted for three symptomatic cases that were regarded as locally acquired infections in reports and diagnosed between Day 58 and Day 67. Assuming that the asymptomatic ratio was 50% [19], we considered that in total there were m = 6 untraced cases including the diagnosed cases.