Temporal dynamics in viral shedding and transmissibility of COVID-19

Xi He; Eric HY Lau; Peng Wu; Xilong Deng; Jian Wang; Xinxin Hao; Yiu Chung Lau; Jessica Y Wong; Yujuan Guan; Xinghua Tan; Xiaoneng Mo; Yanqing Chen; Baolin Liao; Weilie Chen; Fengyu Hu; Qing Zhang; Mingqiu Zhong; Yanrong Wu; Lingzhai Zhao; Fuchun Zhang; Benjamin J Cowling; Fang Li; Gabriel M Leung

Our study has several limitations. First, the infectiousness profile was inferred from infector-infectee pairs and could be affected by the isolation of some cases, as well as behavioral changes after symptom onset such as enhanced personal hygiene and selfisolation. Second, we reviewed available information on known serial intervals, but the observations we identified may have been biased towards shorter intervals because reporting of more recent exposure to sick persons before symptom onsets is more prominent. This may have shifted the inferred infectiousness profile towards negative (i.e. transmission before symptom onset). Nevertheless in our dataset of transmission pairs we were able to capture relatively long serial intervals (e.g. > 10 days), hence the impact on the inferred infectiousness was likely limited. Our simulation also shows how infectiousness starting before symptom onset would be more consistent with the observed serial interval distribution.