The incubation period of SARS is 1–4 days [33]. However, in a small number of patients, the incubation period may be longer than 10 days [34]. It has been demonstrated that the latency of COVID-19 varies from 3–7 days on average, for up to 14 days [35]. During this incubation period, patients are contagious, and it has been reported that each case infected on average 3.77 other people (uncertainty range 2.23-4.82) [36]. By comparison, we found that the average latency of COVID-19 is slightly longer than that of SARS.