Transmission heterogeneities, kinetics, and controllability of SARS-CoV-2

• Published in: Science (American Association for the Advancement of Science) Vol. 371; no. 6526
• Main Authors: Sun, Kaiyuan, Wang, Wei, Gao, Lidong, Wang, Yan, Luo, Kaiwei, Ren, Lingshuang, Zhan, Zhifei, Chen, Xinghui, Zhao, Shanlu, Huang, Yiwei, Sun, Qianlai, Liu, Ziyan, Litvinova, Maria, Vespignani, Alessandro, Ajelli, Marco, Viboud, Cécile, Yu, Hongjie
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 15.01.2021; American Association for the Advancement of Science
• Subjects: Adolescent; Adult; Aged; Asymptomatic Infections; Chain of Infection - prevention & control; Chains; Child; Child, Preschool; China - epidemiology; Communicable Diseases; Computer applications; Contact Tracing; Controllability; Coronaviridae; Coronaviruses; COVID-19; COVID-19 - prevention & control; COVID-19 - transmission; Demography; Diaries; Disease control; Disease transmission; Dynamics; Epidemics; Epidemiology; Exposure; Family Characteristics; Female; Heterogeneity; Households; Humans; Individual Differences; Infant; Infant, Newborn; Infections; Infectious diseases; Infectivity; Intelligence; Kinetics; Male; Mathematical models; Medicine; Middle Aged; Online; Outbreaks; Parameters; Population; Public health; Quarantine; Respiratory diseases; Risk analysis; Risk factors; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Social behavior; Social factors; Social Interaction; Social interactions; Stability; Statistical analysis; Teleworking; Viral diseases; Virus Shedding; Viruses; Young Adult; China
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.abe2424

A minority of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmit most infections. How does this happen? Sun et al. reconstructed transmission in Hunan, China, up to April 2020. Such detailed data can be used to separate out the relative contribution of transmission control measures aimed at isolating individuals relative to population-level distancing measures. The authors found that most of the secondary transmissions could be traced back to a minority of infected individuals, and well over half of transmission occurred in the presymptomatic phase. Furthermore, the duration of exposure to an infected person combined with closeness and number of household contacts constituted the greatest risks for transmission, particularly when lockdown conditions prevailed. These findings could help in the design of infection control policies that have the potential to minimize both virus transmission and economic strain. Science , this issue p. eabe2424 Modeling results indicate that SARS-CoV-2 control requires case isolation, contact quarantine, and population-level interventions. A long-standing question in infectious disease dynamics concerns the role of transmission heterogeneities, which are driven by demography, behavior, and interventions. On the basis of detailed patient and contact-tracing data in Hunan, China, we find that 80% of secondary infections traced back to 15% of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primary infections, which indicates substantial transmission heterogeneities. Transmission risk scales positively with the duration of exposure and the closeness of social interactions and is modulated by demographic and clinical factors. The lockdown period increases transmission risk in the family and households, whereas isolation and quarantine reduce risks across all types of contacts. The reconstructed infectiousness profile of a typical SARS-CoV-2 patient peaks just before symptom presentation. Modeling indicates that SARS-CoV-2 control requires the synergistic efforts of case isolation, contact quarantine, and population-level interventions because of the specific transmission kinetics of this virus.