scholarly journals Country distancing reveals the effectiveness of travel restrictions during COVID-19

2020 ◽  
Author(s):  
Lu Zhong ◽  
Mamadou Diagne ◽  
Weiping Wang ◽  
Jianxi Gao
Keyword(s):  
Mainland China ◽  
Credible Interval ◽  
Economic Loss ◽  
Geographic Area ◽  
Strategic Action ◽  
Infected Case ◽  
Travel Restrictions ◽  
In Series ◽  
Backbone Tree ◽  
Novel Coronavirus

Travel restrictions are the current central strategy to globally stop the transmission of the novel coronavirus disease (COVID-19). Despite remarkably successful approaches in predicting the spatiotemporal patterns of the ongoing pandemic, we lack an intrinsic understanding of the travel restriction's effectiveness. We fill this gap by developing a surprisingly simple measure, country distancing, that is analogical to the effective resistance in series and parallel circuits and captures the propagation backbone tree from the outbreak locations globally. This approach enables us to map the effectiveness of travel restrictions to arrival time delay (ATD) or infected case reduction (ICR) systematically. Our method estimates that 50.8\% of travel restrictions as of Apr-4 are ineffective, resulting in zero ATD or ICR worldwide. Instead, by imposing Hubei's lockdown on Jan-23 and national lockdown on Feb-8, mainland China alone leads to 11.66 [95\% credible interval (CI), 9.71 to 13.92] days of ATD per geographic area and 1,012,233 (95\% CI, 208,210 -4,959,094) ICR in total as of Apr-4. Our result unveils the trade-off between the country distancing increase and economic loss, offering practical guidance for strategic action about when and where to implement travel restrictions, tailed to the real-time national context.

scholarly journals Country distancing increase reveals the effectiveness of travel restrictions in stopping COVID-19 transmission

2020 ◽  
Author(s):  
Lu Zhong ◽  
Mamadou Diagne ◽  
Weiping Wang ◽  
Jianxi Gao
Keyword(s):  
Arrival Time ◽  
Geographical Area ◽  
Credible Interval ◽  
Disease Spread ◽  
Travel Restrictions ◽  
Efficiency And Effectiveness ◽  
In Series ◽  
Arrival Time Delay ◽  
Backbone Tree ◽  
Novel Coronavirus

Abstract Non-pharmaceutical interventions are the current central strategy to stop transmitting the novel coronavirus disease (COVID-19) globally. Despite remarkably successful approaches in predicting the ongoing pandemic's spatiotemporal patterns, we lack an intrinsic understanding of the travel restrictions' efficiency and effectiveness. We fill this gap by examining the countries' closeness based on disease spread using country distancing that is analogical to the effective resistance in series and parallel circuits and captures the propagation backbone tree from the outbreak locations globally. Our method estimates that 53.6\% of travel restrictions as of June 1, 2020, are ineffective. Our analytical results unveil that the optimal and coordinated travel restrictions postpone per geographical area by 22.56 [95\% credible interval (CI), 18.57 to 26.59] days of the disease's arrival time and protect the world by reducing 1,872,295 (95\% CI, 216,029 to 23,606,312) infected cases till June 1, 2020, which are significantly better than the existing travel restrictions achieving 12.87 (95\% CI, 10.59 to 15.17) days of arrival time delay and 861,867 (95\% CI, 238,250 to 3,879,638) infected cases reduction. Our approach offers a practical guide that indicates when and where to implement travel restrictions, tailed to the real-time national context.

scholarly journals Country distancing increase reveals the effectiveness of travel restrictions in stopping COVID-19 transmission

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lu Zhong ◽  
Mamadou Diagne ◽  
Weiping Wang ◽  
Jianxi Gao
Keyword(s):  
Arrival Time ◽  
Geographical Area ◽  
The Novel ◽  
Parallel Circuits ◽  
Travel Restrictions ◽  
In Series ◽  
Disease Spreading ◽  
Backbone Tree ◽  
Novel Coronavirus ◽  
Distance Approach

AbstractDespite a number of successful approaches in predicting the spatiotemporal patterns of the novel coronavirus (COVID-19) pandemic and quantifying the effectiveness of non-pharmaceutical interventions starting from data about the initial outbreak location, we lack an intrinsic understanding as outbreak locations shift and evolve. Here, we fill this gap by developing a country distance approach to capture the pandemic’s propagation backbone tree from a complex airline network with multiple and evolving outbreak locations. We apply this approach, which is analogous to the effective resistance in series and parallel circuits, to examine countries’ closeness regarding disease spreading and evaluate the effectiveness of travel restrictions on delaying infections. In particular, we find that 63.2% of travel restrictions implemented as of 1 June 2020 are ineffective. The remaining percentage postponed the disease arrival time by 18.56 days per geographical area and resulted in a total reduction of 13,186,045 infected cases. Our approach enables us to design optimized and coordinated travel restrictions to extend the delay in arrival time and further reduce more infected cases while preserving air travel.

scholarly journals Risk Assessment of Novel Coronavirus COVID-19 Outbreaks Outside China

2020 ◽  
Vol 9 (2) ◽  
pp. 571 ◽  
Author(s):  
Péter Boldog ◽  
Tamás Tekeli ◽  
Zsolt Vizi ◽  
Attila Dénes ◽  
Ferenc A. Bartha ◽  
...  
Keyword(s):  
Control Measure ◽  
Mainland China ◽  
Destination Country ◽  
Control Measures ◽  
Cumulative Number ◽  
Travel Restrictions ◽  
Imported Cases ◽  
Major Outbreak ◽  
Novel Coronavirus ◽  
Local Reproduction

We developed a computational tool to assess the risks of novel coronavirus outbreaks outside of China. We estimate the dependence of the risk of a major outbreak in a country from imported cases on key parameters such as: (i) the evolution of the cumulative number of cases in mainland China outside the closed areas; (ii) the connectivity of the destination country with China, including baseline travel frequencies, the effect of travel restrictions, and the efficacy of entry screening at destination; and (iii) the efficacy of control measures in the destination country (expressed by the local reproduction number R loc ). We found that in countries with low connectivity to China but with relatively high R loc , the most beneficial control measure to reduce the risk of outbreaks is a further reduction in their importation number either by entry screening or travel restrictions. Countries with high connectivity but low R loc benefit the most from policies that further reduce R loc . Countries in the middle should consider a combination of such policies. Risk assessments were illustrated for selected groups of countries from America, Asia, and Europe. We investigated how their risks depend on those parameters, and how the risk is increasing in time as the number of cases in China is growing.

scholarly journals Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2)

Science ◽  
2020 ◽  
Vol 368 (6490) ◽  
pp. 489-493 ◽  
Author(s):  
Ruiyun Li ◽  
Sen Pei ◽  
Bin Chen ◽  
Yimeng Song ◽  
Tao Zhang ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Transmission Rate ◽  
Credible Interval ◽  
Metapopulation Model ◽  
Mobility Data ◽  
Geographic Spread ◽  
Travel Restrictions ◽  
Rapid Dissemination ◽  
Novel Coronavirus ◽  
Epidemiological Characteristics

Estimation of the prevalence and contagiousness of undocumented novel coronavirus [severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2)] infections is critical for understanding the overall prevalence and pandemic potential of this disease. Here, we use observations of reported infection within China, in conjunction with mobility data, a networked dynamic metapopulation model, and Bayesian inference, to infer critical epidemiological characteristics associated with SARS-CoV-2, including the fraction of undocumented infections and their contagiousness. We estimate that 86% of all infections were undocumented [95% credible interval (CI): 82–90%] before the 23 January 2020 travel restrictions. The transmission rate of undocumented infections per person was 55% the transmission rate of documented infections (95% CI: 46–62%), yet, because of their greater numbers, undocumented infections were the source of 79% of the documented cases. These findings explain the rapid geographic spread of SARS-CoV-2 and indicate that containment of this virus will be particularly challenging.

scholarly journals A data-driven assessment of early travel restrictions related to the spreading of the novel COVID-19 within mainland China

2020 ◽  
Author(s):  
Alberto Aleta ◽  
Qitong Hu ◽  
Jiachen Ye ◽  
Peng Ji ◽  
Yamir Moreno
Keyword(s):  
Mainland China ◽  
Behavioral Changes ◽  
The Novel ◽  
Metapopulation Model ◽  
Short Term ◽  
Effective Measure ◽  
Mobility Data ◽  
Health Authorities ◽  
Travel Restrictions ◽  
Novel Coronavirus

Two months after it was firstly reported, the novel coronavirus disease COVID-19 has already spread worldwide. However, the vast majority of reported infections have occurred in China. To assess the effect of early travel restrictions adopted by the health authorities in China, we have implemented an epidemic metapopulation model that is fed with mobility data corresponding to 2019 and 2020. This allows to compare two radically different scenarios, one with no travel restrictions and another in which mobility is reduced by a travel ban. Our findings indicate that i) travel restrictions are an effective measure in the short term, however, ii) they are ineffective when it comes to completely eliminate the disease. The latter is due to the impossibility of removing the risk of seeding the disease to other regions. Our study also highlights the importance of developing more realistic models of behavioral changes when a disease outbreak is unfolding.

scholarly journals Reconstruction of Transmission Pairs for Novel Coronavirus Disease 2019 (COVID-19) in Mainland China: Estimation of Superspreading Events, Serial Interval, and Hazard of Infection

2020 ◽  
Author(s):  
Xiao-Ke Xu ◽  
Xiao Fan Liu ◽  
Ye Wu ◽  
Sheikh Taslim Ali ◽  
Zhanwei Du ◽  
...  
Keyword(s):  
Social Relationships ◽  
Mainland China ◽  
Credible Interval ◽  
Old People ◽  
Travel History ◽  
Serial Interval ◽  
Significant Barrier ◽  
Working Age ◽  
Novel Coronavirus ◽  
Nonpharmaceutical Interventions

Abstract Background Knowledge on the epidemiological features and transmission patterns of novel coronavirus disease (COVID-19) is accumulating. Detailed line-list data with household settings can advance the understanding of COVID-19 transmission dynamics. Methods A unique database with detailed demographic characteristics, travel history, social relationships, and epidemiological timelines for 1407 transmission pairs that formed 643 transmission clusters in mainland China was reconstructed from 9120 COVID-19 confirmed cases reported during 15 January–29 February 2020. Statistical model fittings were used to identify the superspreading events and estimate serial interval distributions. Age- and sex-stratified hazards of infection were estimated for household vs nonhousehold transmissions. Results There were 34 primary cases identified as superspreaders, with 5 superspreading events occurred within households. Mean and standard deviation of serial intervals were estimated as 5.0 (95% credible interval [CrI], 4.4–5.5) days and 5.2 (95% CrI, 4.9–5.7) days for household transmissions and 5.2 (95% CrI, 4.6–5.8) and 5.3 (95% CrI, 4.9–5.7) days for nonhousehold transmissions, respectively. The hazard of being infected outside of households is higher for people aged 18–64 years, whereas hazard of being infected within households is higher for young and old people. Conclusions Nonnegligible frequency of superspreading events, short serial intervals, and a higher risk of being infected outside of households for male people of working age indicate a significant barrier to the identification and management of COVID-19 cases, which requires enhanced nonpharmaceutical interventions to mitigate this pandemic.

scholarly journals The effect of travel restrictions on the spread of the 2019 novel coronavirus (2019-nCoV) outbreak

2020 ◽  
Author(s):  
Matteo Chinazzi ◽  
Jessica T. Davis ◽  
Marco Ajelli ◽  
Corrado Gioannini ◽  
Maria Litvinova ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Mainland China ◽  
International Travel ◽  
Transmission Model ◽  
Rapid Spread ◽  
Travel Restrictions ◽  
Imported Cases ◽  
Novel Coronavirus ◽  
Disease Transmission Model ◽  
The Impact

AbstractMotivated by the rapid spread of a novel coronavirus (2019-nCoV) in Mainland China, we use a global metapopulation disease transmission model to project the impact of both domestic and international travel limitations on the national and international spread of the epidemic. The model is calibrated on the evidence of internationally imported cases before the implementation of the travel quarantine of Wuhan. By assuming a generation time of 7.5 days, the reproduction number is estimated to be 2.4 [90% CI 2.2-2.6]. The median estimate for number of cases before the travel ban implementation on January 23, 2020 is 58,956 [90% CI 40,759 - 87,471] in Wuhan and 3,491 [90% CI 1,924 - 7,360] in other locations in Mainland China. The model shows that as of January 23, most Chinese cities had already received a considerable number of infected cases, and the travel quarantine delays the overall epidemic progression by only 3 to 5 days. The travel quarantine has a more marked effect at the international scale, where we estimate the number of case importations to be reduced by 80% until the end of February. Modeling results also indicate that sustained 90% travel restrictions to and from Mainland China only modestly affect the epidemic trajectory unless combined with a 50% or higher reduction of transmission in the community.

scholarly journals Risk Assessment of Novel Coronavirus COVID-19 Outbreaks Outside China

2020 ◽  
Author(s):  
Péter Boldog ◽  
Tamás Tekeli ◽  
Zsolt Vizi ◽  
Attila Dénes ◽  
Ferenc A. Bartha ◽  
...  
Keyword(s):  
Control Measure ◽  
Mainland China ◽  
Destination Country ◽  
Control Measures ◽  
Cumulative Number ◽  
Travel Restrictions ◽  
Imported Cases ◽  
Major Outbreak ◽  
Novel Coronavirus ◽  
Local Reproduction

AbstractWe developed a computational tool to assess the risks of novel coronavirus outbreaks outside of China. We estimate the dependence of the risk of a major outbreak in a country from imported cases on key parameters such as: (i) the evolution of the cumulative number of cases in mainland China outside the closed areas; (ii) the connectivity of the destination country with China, including baseline travel frequencies, the effect of travel restrictions, and the efficacy of entry screening at destination; and (iii) the efficacy of control measures in the destination country (expressed by the local reproduction number Rloc). We found that in countries with low connectivity to China but with relatively high Rloc, the most beneficial control measure to reduce the risk of outbreaks is a further reduction in their importation number either by entry screening or travel restrictions. Countries with high connectivity but low Rloc benefit the most from policies that further reduce Rloc. Countries in the middle should consider a combination of such policies. Risk assessments were illustrated for selected groups of countries from America, Asia, and Europe. We investigated how their risks depend on those parameters, and how the risk is increasing in time as the number of cases in China is growing.

scholarly journals Intrinsic growth rules of patients infected, dead and recovered with 2019 novel coronavirus in mainland China

2020 ◽  
Author(s):  
Chuanliang Han ◽  
Yimeng Liu ◽  
Saini Yang
Keyword(s):  
Public Health ◽  
Time Series ◽  
Severe Acute Respiratory Syndrome ◽  
Time Series Data ◽  
Mainland China ◽  
Series Data ◽  
Cumulative Number ◽  
Descriptive Model ◽  
Infected Case ◽  
Novel Coronavirus

AbstractAn outbreak of a novel coronavirus (SARS-CoV-2)-infected pneumonia (COVID-19) was first diagnosed in Wuhan, China, in December 2019 and then spread rapidly to other regions. We collected the time series data of the cumulative number of confirmed infected, dead, and cured cases from the health commissions in 31 provinces in mainland China. A descriptive model in a logistic form was formulated to infer the intrinsic epidemic rules of COVID-19, which illustrates robustness spatially and temporally. Our model is robust (R2>0.95) to depict the intrinsic growth rule for the cumulative number of confirmed infected, dead, and cured cases in 31 provinces in mainland China. Furthermore, we compared the intrinsic epidemic rules of COVID-19 in Hubei with that of severe acute respiratory syndrome (SARS) in Beijing, which was obtained from the Ministry of Public Health of China in 2003. We found that the infected case is the earliest to be saturated and has the lowest semi-saturation period compared with deaths and cured cases for both COVID-19 and SARS. All the three types of SARS cases are later to saturate and have longer semi-saturation period than that of COVID-19. Despite the virus caused SARS (SARS-CoV) and the virus caused COVID-19 (SARS-CoV-2) are homologous, the duration of the outbreak would be shorter for COVID-19.

scholarly journals Effectiveness of quarantine measure on transmission dynamics of COVID-19 in Hong Kong

2020 ◽  
Author(s):  
Hsiang-Yu Yuan ◽  
Axiu Mao ◽  
Guiyuan Han ◽  
Hsiangkuo Yuan ◽  
Dirk Pfeiffer
Keyword(s):  
Hong Kong ◽  
Symptom Onset ◽  
Mainland China ◽  
Economic Loss ◽  
Control Measures ◽  
Rapid Expansion ◽  
Transmission Dynamics ◽  
Reproductive Number ◽  
Suspected Case ◽  
Infected Case

AbstractThe rapid expansion of COVID-19 has caused a global pandemic. Although quarantine measures have been used widely, the critical steps among them to suppress the outbreak without a huge social-economic loss remain unknown. Hong Kong, unlike other regions in the world, had a massive number of travellers from Mainland China during the early expansion period, and yet the spread of virus has been relatively limited. Understanding the effect of control measures to reduce the transmission in Hong Kong can improve the control of the virus spreading.We have developed a susceptible-exposed-infectious-quarantined-recovered (SEIQR) meta-population model that can stratify the infections into imported and subsequent local infections, and therefore to obtain the control effects on transmissibility in a region with many imported cases. We fitted the model to both imported and local confirmed cases with symptom onset from 18 January to 29 February 2020 in Hong Kong with daily transportation data and the transmission dynamics from Wuhan and Mainland China.The model estimated that the reproductive number was dropped from 2.32 to 0.76 (95% CI, 0.66 to 0.86) after an infected case was estimated to be quarantined half day before the symptom onset, corresponding to the incubation time of 5.43 days (95% CI, 1.30-9.47). If the quarantine happened about one day after the onset, community spread would be likely to occur, indicated by the reproductive number larger than one. The results suggest that the early quarantine for a suspected case before the symptom onset is a key factor to suppress COVID-19.

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