Open Access
Feasibility of controlling COVID-19 outbreaks by isolation of cases and contacts
Joel Hellewell,Sam Abbott,Amy Gimma,Nikos I Bosse,Christopher I Jarvis,Timothy W Russell,James D Munday,Adam J. Kucharski,W. John Edmunds +8 more
TLDR
A mathematical model is used to assess if isolation and contact tracing are able to control onwards transmission from imported cases of COVID-19 and quantify the potential effectiveness of contact tracing and isolation of cases at controlling a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-like pathogen.Abstract:
Summary
Background
Isolation of cases and contact tracing is used to control outbreaks of infectious diseases, and has been used for coronavirus disease 2019 (COVID-19). Whether this strategy will achieve control depends on characteristics of both the pathogen and the response. Here we use a mathematical model to assess if isolation and contact tracing are able to control onwards transmission from imported cases of COVID-19.
Methods
We developed a stochastic transmission model, parameterised to the COVID-19 outbreak. We used the model to quantify the potential effectiveness of contact tracing and isolation of cases at controlling a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-like pathogen. We considered scenarios that varied in the number of initial cases, the basic reproduction number (R
0), the delay from symptom onset to isolation, the probability that contacts were traced, the proportion of transmission that occurred before symptom onset, and the proportion of subclinical infections. We assumed isolation prevented all further transmission in the model. Outbreaks were deemed controlled if transmission ended within 12 weeks or before 5000 cases in total. We measured the success of controlling outbreaks using isolation and contact tracing, and quantified the weekly maximum number of cases traced to measure feasibility of public health effort.
Findings
Simulated outbreaks starting with five initial cases, an R
0 of 1·5, and 0% transmission before symptom onset could be controlled even with low contact tracing probability; however, the probability of controlling an outbreak decreased with the number of initial cases, when R
0 was 2·5 or 3·5 and with more transmission before symptom onset. Across different initial numbers of cases, the majority of scenarios with an R
0 of 1·5 were controllable with less than 50% of contacts successfully traced. To control the majority of outbreaks, for R
0 of 2·5 more than 70% of contacts had to be traced, and for an R
0 of 3·5 more than 90% of contacts had to be traced. The delay between symptom onset and isolation had the largest role in determining whether an outbreak was controllable when R
0 was 1·5. For R
0 values of 2·5 or 3·5, if there were 40 initial cases, contact tracing and isolation were only potentially feasible when less than 1% of transmission occurred before symptom onset.
Interpretation
In most scenarios, highly effective contact tracing and case isolation is enough to control a new outbreak of COVID-19 within 3 months. The probability of control decreases with long delays from symptom onset to isolation, fewer cases ascertained by contact tracing, and increasing transmission before symptoms. This model can be modified to reflect updated transmission characteristics and more specific definitions of outbreak control to assess the potential success of local response efforts.
Funding
Wellcome Trust, Global Challenges Research Fund, and Health Data Research UK.
read more
Citations
More filters
Journal ArticleDOI
Temporal dynamics in viral shedding and transmissibility of COVID-19.
Xi He,Eric H. Y. 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 +22 more
TL;DR: It is estimated that 44% (95% confidence interval, 25–69%) of secondary cases were infected during the index cases’ presymptomatic stage, in settings with substantial household clustering, active case finding and quarantine outside the home.
Journal ArticleDOI
How will country-based mitigation measures influence the course of the COVID-19 epidemic?
TL;DR: In this view, COVID-19 has developed into a pandemic, with small chains of transmission in many countries and large chains resulting in extensive spread in a few countries, such as Italy, Iran, South Korea, and Japan and it is unclear whether other countries can implement the stringent measures China eventually adopted.
Journal ArticleDOI
Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing.
Luca Ferretti,Chris Wymant,Michelle Kendall,Lele Zhao,Anel Nurtay,Lucie Abeler-Dörner,Michael Parker,David Bonsall,Christophe Fraser +8 more
TL;DR: A mathematical model for infectiousness was developed to estimate the basic reproductive number R0 and to quantify the contribution of different transmission routes and the requirements for successful contact tracing, and the combination of two key parameters needed to reduce R0 to less than 1 was determined.
Journal ArticleDOI
Modelling the COVID-19 epidemic and implementation of population-wide interventions in Italy.
Giulia Giordano,Franco Blanchini,Raffaele Bruno,Patrizio Colaneri,Alessandro Di Filippo,Angela Di Matteo,Marta Colaneri +6 more
TL;DR: In this paper, the authors proposed a new model that predicts the course of the SARS-CoV-2 pandemic to help plan an effective control strategy, including social distancing, testing and contact tracing.
Journal ArticleDOI
Spread and dynamics of the COVID-19 epidemic in Italy: Effects of emergency containment measures.
Marino Gatto,Enrico Bertuzzo,Lorenzo Mari,Stefano Miccoli,Luca Carraro,Renato Casagrandi,Andrea Rinaldo +6 more
TL;DR: Although a number of assumptions need to be reexamined, like age structure in social mixing patterns and in the distribution of mobility, hospitalization, and fatality, it is concluded that verifiable evidence exists to support the planning of emergency measures.
References
More filters
Journal ArticleDOI
Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China
Chaolin Huang,Yeming Wang,Xingwang Li,Lili Ren,Jianping Zhao,Yi Hu,Li Zhang,Guohui Fan,Jiuyang Xu,Xiaoying Gu,Zhenshun Cheng,Ting Yu,Jia'an Xia,Yuan Wei,Wenjuan Wu,Xuelei Xie,Wen Yin,Li Hui,Min Liu,Yan Xiao,Hong Gao,Li Guo,Jungang Xie,Guang-Fa Wang,Rongmeng Jiang,Zhancheng Gao,Qi Jin,Jianwei Wang,Bin Cao +28 more
TL;DR: The epidemiological, clinical, laboratory, and radiological characteristics and treatment and clinical outcomes of patients with laboratory-confirmed 2019-nCoV infection in Wuhan, China, were reported.
Journal ArticleDOI
Early Transmission Dynamics in Wuhan, China, of Novel Coronavirus-Infected Pneumonia.
Qun Li,Xuhua Guan,Peng Wu,Xiaoye Wang,Lei Zhou,Yeqing Tong,Ruiqi Ren,Kathy Leung,Eric H. Y. Lau,Jessica Y. Wong,Xuesen Xing,Nijuan Xiang,Yang Wu,Chao Li,Chen Qi,Dan Li,Tian Liu,Jing Zhao,Man Liu,Wenxiao Tu,Chuding Chen,Lianmei Jin,Rui Yang,Qi Wang,Suhua Zhou,Rui Wang,Hui Liu,Yingbo Luo,Yuan Liu,Ge Shao,Huan Li,Zhongfa Tao,Yang Yang,Yang Yang,Zhiqiang Deng,Boxi Liu,Zhitao Ma,Yanping Zhang,Guoqing Shi,Tommy Tsan-Yuk Lam,Joseph T. Wu,George F. Gao,George F. Gao,Benjamin J. Cowling,Bo Yang,Gabriel M. Leung,Zijian Feng +46 more
TL;DR: There is evidence that human-to-human transmission has occurred among close contacts since the middle of December 2019 and considerable efforts to reduce transmission will be required to control outbreaks if similar dynamics apply elsewhere.
Journal ArticleDOI
Superspreading and the effect of individual variation on disease emergence
TL;DR: It is shown that contact tracing data from eight directly transmitted diseases shows that the distribution of individual infectiousness around R0 is often highly skewed, and implications for outbreak control are explored, showing that individual-specific control measures outperform population-wide measures.
Journal ArticleDOI
Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: A data-driven analysis in the early phase of the outbreak.
Shi Zhao,Qianying Lin,Jinjun Ran,Salihu S. Musa,Guangpu Yang,Weiming Wang,Yijun Lou,Daozhou Gao,Lin Yang,Daihai He,Maggie Haitian Wang +10 more
TL;DR: The early outbreak data largely follows the exponential growth and indicates the potential of 2019-nCoV to cause outbreaks, as well as the impact of the variations in disease reporting rate, modelled through theonential growth.
Journal ArticleDOI
Incubation period of 2019 novel coronavirus (2019-nCoV) infections among travellers from Wuhan, China, 20-28 January 2020.
TL;DR: Using the travel history and symptom onset of 88 confirmed cases that were detected outside Wuhan in the early outbreak phase, the mean incubation period is estimated to be 6.4 days, which should help inform 2019-nCoV case definitions and appropriate quarantine durations.