Viral dynamics in asymptomatic patients with COVID-19

Zhou, Rui; Li, Furong; Chen, Fengjuan; Liu, Huamin; Zheng, Jiazhen; Lei, Chunliang; Wu, Xianbo

Abstract Data are limited on the viral load, viral shedding patterns and potential infectivity of asymptomatic patients (APs) with coronavirus disease 2019 (COVID-19). We included 31 adult patients who were virologically confirmed to have COVID-19 but were asymptomatic on admission. Among these 31 patients, 22 presented symptoms after admission and were defined as asymptomatic patients in incubation period (APIs); the other 9 patients remained asymptomatic during hospitalization and were defined as asymptomatic patients (APs). The cycle threshold (Ct) values of APs (39.0, IQR 37.5-39.5) was significantly higher than those of APIs (34.5, IQR 32.2-37.0), which indicated a lower viral load in APs, but the duration of viral shedding remained similar between the two groups (7 days IQR 5-14 vs. 8 days IQR 5-16). The study findings demonstrated that although they have a lower viral load, APs with COVID-19 still have certain period of viral shedding, which suggests the possibility of transmission during their asymptomatic period. Further longitudinal surveillance of these asymptomatic cases via virus nucleic acid tests are warranted.