scholarly journals Estimating the number of undetected COVID-19 cases among travellers from mainland China

2021 ◽  
Vol 5 ◽  
pp. 143
Author(s):  
Sangeeta Bhatia ◽  
Natsuko Imai ◽  
Gina Cuomo-Dannenburg ◽  
Marc Baguelin ◽  
Adhiratha Boonyasiri ◽  
...  
Keyword(s):  
Mainland China ◽  
Relative Sensitivity ◽  
Absolute Number ◽  
Wuhan City ◽  
The World ◽  
Travel Restrictions ◽  
Imported Cases ◽  
The Absolute ◽  
Country Specific

Background: As of August 2021, every region of the world has been affected by the COVID-19 pandemic, with more than 196,000,000 cases worldwide. Methods: We analysed COVID-19 cases among travellers from mainland China to different regions and countries, comparing the region- and country-specific rates of detected and confirmed cases per flight volume to estimate the relative sensitivity of surveillance in different regions and countries. Results: Although travel restrictions from Wuhan City and other cities across China may have reduced the absolute number of travellers to and from China, we estimated that up to 70% (95% CI: 54% - 80%) of imported cases could remain undetected relative to the sensitivity of surveillance in Singapore. The percentage of undetected imported cases rises to 75% (95% CI 66% - 82%) when comparing to the surveillance sensitivity in multiple countries. Conclusions: Our analysis shows that a large number of COVID-19 cases remain undetected across the world. These undetected cases potentially resulted in multiple chains of human-to-human transmission outside mainland China.

scholarly journals Estimating the number of undetected COVID-19 cases among travellers from mainland China

2021 ◽  
Vol 5 ◽  
pp. 143
Author(s):  
Sangeeta Bhatia ◽  
Natsuko Imai ◽  
Gina Cuomo-Dannenburg ◽  
Marc Baguelin ◽  
Adhiratha Boonyasiri ◽  
...  
Keyword(s):  
Mainland China ◽  
Relative Sensitivity ◽  
Absolute Number ◽  
Wuhan City ◽  
The World ◽  
Travel Restrictions ◽  
Imported Cases ◽  
The Absolute ◽  
Country Specific

Background: As of August 2021, every region of the world has been affected by the COVID-19 pandemic, with more than 196,000,000 cases worldwide. Methods: We analysed COVID-19 cases among travellers from mainland China to different regions and countries, comparing the region- and country-specific rates of detected and confirmed cases per flight volume to estimate the relative sensitivity of surveillance in different regions and countries. Results: Although travel restrictions from Wuhan City and other cities across China may have reduced the absolute number of travellers to and from China, we estimated that up to 70% (95% CI: 54% - 80%) of imported cases could remain undetected relative to the sensitivity of surveillance in Singapore. The percentage of undetected imported cases rises to 75% (95% CI 66% - 82%) when comparing to the surveillance sensitivity in multiple countries. Conclusions: Our analysis shows that a large number of COVID-19 cases remain undetected across the world. These undetected cases potentially resulted in multiple chains of human-to-human transmission outside mainland China.

scholarly journals Estimating the number of undetected COVID-19 cases among travellers from mainland China

2020 ◽  
Vol 5 ◽  
pp. 143
Author(s):  
Sangeeta Bhatia ◽  
Natsuko Imai ◽  
Gina Cuomo-Dannenburg ◽  
Marc Baguelin ◽  
Adhiratha Boonyasiri ◽  
...  
Keyword(s):  
Mainland China ◽  
Relative Sensitivity ◽  
Absolute Number ◽  
Wuhan City ◽  
Travel Restrictions ◽  
The Absolute ◽  
Country Specific

Background: Since the start of the COVID-19 epidemic in late 2019, there have been more than 152 affected regions and countries with over 110,000 confirmed cases outside mainland China. Methods: We analysed COVID-19 cases among travellers from mainland China to different regions and countries, comparing the region- and country-specific rates of detected and confirmed cases per flight volume to estimate the relative sensitivity of surveillance in different regions and countries. Results: Although travel restrictions from Wuhan City and other cities across China may have reduced the absolute number of travellers to and from China, we estimated that more than two thirds (70%, 95% CI: 54% - 80%, compared to Singapore; 75%, 95% CI: 66% - 82%, compared to multiple countries) of cases exported from mainland China have remained undetected. Conclusions: These undetected cases potentially resulted in multiple chains of human-to-human transmission outside mainland China.

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 Determining travel fluxes in epidemic areas

2021 ◽  
Vol 17 (10) ◽  
pp. e1009473
Author(s):  
Daipeng Chen ◽  
Yuyi Xue ◽  
Yanni Xiao
Keyword(s):  
Infectious Diseases ◽  
Mainland China ◽  
Diffusion Distance ◽  
Population Movements ◽  
Spatial Spread ◽  
Active Population ◽  
Source Data ◽  
The World ◽  
Travel Restrictions ◽  
Random Diffusion

Infectious diseases attack humans from time to time and threaten the lives and survival of people all around the world. An important strategy to prevent the spatial spread of infectious diseases is to restrict population travel. With the reduction of the epidemic situation, when and where travel restrictions can be lifted, and how to organize orderly movement patterns become critical and fall within the scope of this study. We define a novel diffusion distance derived from the estimated mobility network, based on which we provide a general model to describe the spatiotemporal spread of infectious diseases with a random diffusion process and a deterministic drift process of the population. We consequently develop a multi-source data fusion method to determine the population flow in epidemic areas. In this method, we first select available subregions in epidemic areas, and then provide solutions to initiate new travel flux among these subregions. To verify our model and method, we analyze the multi-source data from mainland China and obtain a new travel flux triggering scheme in the selected 29 cities with the most active population movements in mainland China. The testable predictions in these selected cities show that reopening the borders in accordance with our proposed travel flux will not cause a second outbreak of COVID-19 in these cities. The finding provides a methodology of re-triggering travel flux during the weakening spread stage of the epidemic.

scholarly journals Risk assessment of importation and local transmissions of COVID-19 in Korea (Preprint)

2020 ◽  
Author(s):  
Hyojung Lee ◽  
Yeahwon Kim ◽  
Eunsu Kim ◽  
Sunmi ‍Lee
Keyword(s):  
Risk Assessment ◽  
South Korea ◽  
Basic Reproduction Number ◽  
Reproduction Number ◽  
Mitigation Strategies ◽  
Social Distancing ◽  
The World ◽  
Imported Cases ◽  
The Basic Reproduction Number ◽  
Country Specific

BACKGROUND The emergence of COVID-19 has posed a serious threat to humans all around the world despite recent achievements of vaccines, antiviral drugs, and medical infrastructure. Our modern society has evolved too complex and most of the countries are tightly connected on a global scale. This makes it nearly impossible to implement perfect and prompt mitigation strategies for the COVID-19 outbreaks. Especially, due to the explosive growth of international travels, the diverse network and complexity of human mobility become an essential factor that gives rise to the spread of COVID-19 globally within a very short time. OBJECTIVE South Korea is one of the countries that have experienced the early stage of the COVID-19 pandemic. In the absence of vaccines and treatments, South Korea has implemented and maintained stringent interventions such as large-scale epidemiological investigation, rapid diagnosis, social distancing, and prompt clinical classification of severe patients with appropriate medical measures. In particular, South Korea has been implementing effective screening and quarantine at the airport. In this work, we aim to investigate the impacts of such effective interventions on international travels which can prevent local transmission of COVID-19. METHODS The relation between the number of passengers and the number of imported cases were analyzed. Based on the relation, we have assessed the country-specific risk as the spread of COVID-19 gets expanded from January to October 2020. Moreover, a renewal mathematical modeling has been employed incorporating the risk assessment to capture both imported and local cases of COVID-19 in South Korea. We have estimated the basic reproduction number and the effective reproduction number accounting for both imported and local cases. RESULTS The basic reproduction number (R_0) was estimated at 1.87 (95% CI : 1.47, 2.35) with the rate (α =0.07)of the secondary transmission caused by the imported cases. The time-varying basic reproduction number (effective reproduction number, R_t) was estimated. Our results indicate that the prompt implementation of case-isolation and quarantine were effective to reduce the. secondary cases from imported cases in spite of constant inflows from high-risk countries of COVID-19 all throughout the year 2020. Moreover, various mitigation interventions including social distancing and movement restriction have been maintained effectively to reduce the spread of local cases in South Korea. CONCLUSIONS We have investigated the relative risk of importation of COVID-19, using the country-specific epidemiological data, and passenger volume. By combining the social distancing, screening, and self-quarantine for all travelers entering Korea, the mitigation of COVID-19 transmission caused by imported cases in Korea was highly successful. Those efforts, accompanied by identification of the source of infection, the strengthened quarantine measures for travelers from overseas countries, should be continued. However, the recent new coronavirus variant originated from South Africa has been threatening to get back to the strict border control and lockdown of all around the world again. Therefore, it is urgent to assess the importation risk and maintain an effective surveillance system of COVID-19 in South Korea.

1. Introduction

2018 ◽  
pp. 1-19
Author(s):  
Philip N. Jefferson
Keyword(s):  
Public Policy ◽  
Poverty Reduction ◽  
Absolute Number ◽  
Standard Of Living ◽  
Global Issue ◽  
The World ◽  
The Absolute ◽  
The Many ◽  
Political Economic ◽  
Causes Of Poverty

Poverty is a global issue. There are people in every country with a standard of living that is significantly lower than that of others. Nevertheless, the absolute number of people living in poverty has decreased since 1990, especially in the poorest countries in the world. Therefore, there is reason to hope that further poverty reduction can occur. The Introduction outlines the pervasiveness and trends in poverty around the world; the many different causes of poverty that embed themselves in social, political, economic, educational, and technological processes, which affect all of us from birth to death; and considers why poverty matters. Overall, the economy suffers if systematic public policy does not address poverty.

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 How does the outbreak of 2019-nCoV spread in mainland China? A retrospective analysis of the dynamic transmission routes*

2020 ◽  
Author(s):  
Xiandeng Jiang ◽  
Le Chang ◽  
Yanlin Shi
Keyword(s):  
Migrant Workers ◽  
Mainland China ◽  
The Self ◽  
Var Model ◽  
Time Varying ◽  
Crucial Importance ◽  
Wuhan City ◽  
Government Interventions ◽  
Vector Autoregressive ◽  
Travel Restrictions

AbstractThe fourth outbreak of the Coronaviruses, known as the 2019-nCoV, has occurred in Wuhan city of Hubei province in China in December 2019. We propose a time- varying sparse vector autoregressive (VAR) model to retrospectively analyze and visualize the dyamic transmission routes of this outbreak in mainland China over January 31 – February 19, 2020. Our results demonstrate that the influential interprovince routes from Hubei have become unidentifiable since February 4, whereas the self-transmission in each province was accelerating over February 4–15. From February 16, all routes became less detectable, and no influential transmissions could be identified on February 18 and 19. Such evidence supports the effectiveness of government interventions, including the travel restrictions in Hubei. Implications of our results suggest that in addition to the origin of the outbreak, virus preventions are of crucial importance in provinces with the largest migrant workers percentages (e.g., Jiangxi, Henan and Anhui) to controlling the spread of 2019-nCoV.

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 Life during COVID-19 outbreak: perspective of foreign medical students in Shanghai, China

2020 ◽  
Vol 7 (1) ◽  
pp. 104-106
Author(s):  
Jenifei Shah ◽  
Jesifei Shah ◽  
Rewina Kebede Girmay ◽  
Javaria Nasir
Keyword(s):  
Medical Students ◽  
Mainland China ◽  
The Other ◽  
Single Digit ◽  
Imported Case ◽  
Other Hand ◽  
Corona Virus ◽  
Global Pandemic ◽  
The World ◽  
Imported Cases

This is the experience of medical students during COVID-19 in Shanghai; following the outbreak of corona virus and lockdown of Wuhan, China, on 23 January 2020, one day before the Chinese new year eve.1,2 Since then, the virus has been declared a global pandemic, and life around the world has come to an abrupt halt. On the other hand, things in Wuhan and China have started picking up, following lifting of the 76-Day long lockdown on 7 April.3 The recovery in China, Korea, and Singapore shows promise and hope for the rest of the world, to persevere and weather out the storm. Daily cases in China is in single digit now, and most are imported cases.4 Shanghai reported one imported case of COVID-19, zero locally transmitted case on Thursday 23 April, with a total of 339 locally transmitted confirmed cases, including seven deaths till date, and 1,618 imported cases in mainland China.5,6 No deaths have been reported from the imported cases.6

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