TY - JOUR TI - Evidence for transmission of COVID-19 prior to symptom onset AU - Tindale, Lauren C AU - Stockdale, Jessica E AU - Coombe, Michelle AU - Garlock, Emma S AU - Lau, Wing Yin Venus AU - Saraswat, Manu AU - Zhang, Louxin AU - Chen, Dongxuan AU - Wallinga, Jacco AU - Colijn, Caroline A2 - Franco, Eduardo A2 - Lipsitch, Marc A2 - Lipsitch, Marc A2 - Miller, Joel A2 - Pitzer, Virginia E VL - 9 PY - 2020 DA - 2020/06/22 SP - e57149 C1 - eLife 2020;9:e57149 DO - 10.7554/eLife.57149 UR - https://doi.org/10.7554/eLife.57149 AB - We collated contact tracing data from COVID-19 clusters in Singapore and Tianjin, China and estimated the extent of pre-symptomatic transmission by estimating incubation periods and serial intervals. The mean incubation periods accounting for intermediate cases were 4.91 days (95%CI 4.35, 5.69) and 7.54 (95%CI 6.76, 8.56) days for Singapore and Tianjin, respectively. The mean serial interval was 4.17 (95%CI 2.44, 5.89) and 4.31 (95%CI 2.91, 5.72) days (Singapore, Tianjin). The serial intervals are shorter than incubation periods, suggesting that pre-symptomatic transmission may occur in a large proportion of transmission events (0.4–0.5 in Singapore and 0.6–0.8 in Tianjin, in our analysis with intermediate cases, and more without intermediates). Given the evidence for pre-symptomatic transmission, it is vital that even individuals who appear healthy abide by public health measures to control COVID-19. KW - COVID19 KW - Sars-CoV-2 KW - coronavirus KW - transmission KW - incubation KW - serial interval JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -