The evidence of indirect transmission of SARS-CoV-2 reported in Guangzhou, China

• Published in: BMC public health 2020-08, Vol.20 (1), p.1202-9, Article 1202
• Main Authors: Xie, Chaojun, Zhao, Hongjun, Li, Kuibiao, Zhang, Zhoubin, Lu, Xiaoxiao, Peng, Huide, Wang, Dahu, Chen, Jin, Zhang, Xiao, Wu, Di, Gu, Yuzhou, Yuan, Jun, Zhang, Lin, Lu, Jiachun
• Format: Article
• Language: English
• Subjects: Acids; Adult; Aged; Asymptomatic; Betacoronavirus - isolation & purification; Big Data; Causes of; China; China - epidemiology; Cluster Analysis; Clusters; Contact Tracing; Contaminants; Coronavirus Infections - epidemiology; Coronavirus Infections - transmission; Coronaviruses; COVID-19; Cross-Sectional Studies; Data analysis; Disease control; Disease prevention; Disease transmission; Distribution; Elevators & escalators; Environmental Microbiology; Epidemics; Epidemiology; Family; Female; Fever; Health aspects; Home environment; Hospitals; Humans; Indirect transmission; Inspection; Male; Medical laboratories; Medical research; Middle Aged; Novel coronavirus disease; Pandemics; Patients; Pneumonia, Viral - epidemiology; Pneumonia, Viral - transmission; Polymerase chain reaction; Public health; Questionnaires; Real-Time Polymerase Chain Reaction; Residence Characteristics; Residential areas; Residential buildings; RNA-directed DNA polymerase; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Signs and symptoms; Snot-oral transmission; Software; Statistics; Ultrasonic testing; Viral diseases; Viruses
• ISSN: 1471-2458; 1471-2458
• DOI: 10.1186/s12889-020-09296-y

More than 2 months have passed since the novel coronavirus disease 2019 (COVID-19) first emerged in Wuhan, China. With the migration of people, the epidemic has rapidly spread within China and throughout the world. Due to the severity of the epidemic, undiscovered transmission of COVID-19 deserves further investigation. The aim of our study hypothesized possible modes of SARS-CoV-2 transmission and how the virus may have spread between two family clusters within a residential building in Guangzhou, China. In a cross-sectional study, we monitored and traced confirmed patients and their close contacts from January 11 to February 5, 2020 in Guangzhou, China, including 2 family cluster cases and 61 residents within one residential building. The environmental samples of the building and the throat swabs from the patients and from their related individuals were collected for SARS-CoV-2 and tested with real-time reverse transcriptase polymerase chain reaction (RT-PCR). The relevant information was collected and reported using big data tools. There were two notable family cluster cases in Guangzhou, which included 3 confirmed patients (family No.1: patient A, B, C) and 2 confirmed patients (family No.2: patient D, E), respectively. None of patients had contact with other confirmed patients before the onset of symptoms, and only patient A and patient B made a short stop in Wuhan by train. Home environment inspection results showed that the door handle of family No.1 was positive of SARS-CoV-2. The close contacts of the 5 patients all tested negative of SARS-CoV-2 and in good health, and therefore were released after the official medical observation period of 14-days. Finally, according to the traceability investigation through applying big data analysis, we found an epidemiological association between family No.1 and family No.2, in which patient D (family No.2) was infected through touching an elevator button contaminated by snot with virus from patient A (family No.1) on the same day. Contaminants with virus from confirmed patients can pollute the environment of public places, and the virus can survive on the surface of objects for a short period of time. Therefore, in addition to the conventional droplet transmission, there is also indirect contact transmission such as snot-oral transmission that plays a crucial role in community spread of the virus.