Effective control of SARS-CoV-2 transmission in Wanzhou, China

• Published in: Nature medicine Vol. 27; no. 1; pp. 86 - 93
• Main Authors: Shi, Qiuling, Hu, Yaoyue, Peng, Bin, Tang, Xiao-Jun, Wang, Wei, Su, Kun, Luo, Chao, Wu, Bo, Zhang, Fan, Zhang, Yong, Anderson, Benjamin, Zhong, Xiao-Ni, Qiu, Jing-Fu, Yang, Cheng Yong, Huang, Ai-Long
• Format: Journal Article
• Language: English
• Published: United States Nature Publishing Group 01.01.2021
• Subjects: Adult; Asymptomatic; Basic Reproduction Number; Carrier State; Child; China - epidemiology; Communicable Disease Control; Confidence intervals; Contact; Contact Tracing; Coronaviridae; Coronaviruses; COVID-19; COVID-19 - epidemiology; COVID-19 - prevention & control; COVID-19 - transmission; Disease control; Disease transmission; Epidemiology; Female; Health risks; Humans; Infection control; Male; Methods; Middle Aged; Respiratory diseases; Risk analysis; Risk factors; SARS-CoV-2 - physiology; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Ultrasonic testing; Viral diseases; China
• ISSN: 1078-8956; 1546-170X
• DOI: 10.1038/s41591-020-01178-5

The effectiveness of control measures to contain coronavirus disease 2019 (COVID-19) in Wanzhou, China was assessed. Epidemiological data were analyzed for 183 confirmed COVID-19 cases and their close contacts from five generations of transmission of severe acute respiratory syndrome coronavirus 2 throughout the entire COVID-19 outbreak in Wanzhou. Approximately 67.2% and 32.8% of cases were symptomatic and asymptomatic, respectively. Asymptomatic and presymptomatic transmission accounted for 75.9% of the total recorded transmission. The reproductive number was 1.64 (95% confidence interval: 1.16-2.40) for G1-to-G2 transmission, decreasing to 0.31-0.39 in later generations, concomitant with implementation of rigorous control measures. Substantially higher infection risk was associated with contact within 5 d after the infectors had been infected, frequent contact and ≥8 h of contact duration. The spread of COVID-19 was effectively controlled in Wanzhou by breaking the transmission chain through social distancing, extensive contact tracing, mass testing and strict quarantine of close contacts.