The information presented in this rapid summary is based on a rapid, selective, and non-exhaustive review of the data available in the literature as of June 2, 2020. It is subject to update as new knowledge becomes available. We distinguish between infected individuals who never develop symptoms after sufficient follow-up to rule out their occurrence (asymptomatic form in the strict sense) and individuals without symptoms at the time of their laboratory confirmation (including asymptomatic and presymptomatic forms). We focus on the proportion of asymptomatic cases and the potential for transmission during the presymptomatic or incubation phase. The results show that nearly a quarter of SARS-CoV-2 infections remain asymptomatic and that, in the context of active contact tracing, approximately 50% of transmissions occur during the source patient’s presymptomatic phase. We found no evidence to characterize the transmission potential of completely silent forms of infection.