scholarly journals Transmission dynamics of coronavirus disease 2019 outside of Daegu-Gyeongsangbuk provincial region in South Korea

2020 ◽  
Author(s):  
Sukhyun Ryu ◽  
Sheikh Taslim Ali ◽  
Cheolsun Jang ◽  
Baekjin Kim ◽  
Benjamin J. Cowling
Keyword(s):  
South Korea ◽  
Transmission Dynamics ◽  
Epidemic Control

AbstractWe analyzed transmission of coronavirus disease 2019 in South Korea. We estimated that non-pharamaceutical measures reduced the immediate transmissibility by maximum of 34% for coronavirus disease 2019. Continuous efforts are needed for monitoring the transmissibility to optimize epidemic control.

scholarly journals Transmission dynamics of the delta variant of SARS-CoV-2 infections in Daejeon, South Korea

2021 ◽  
Author(s):  
Hari Hwang ◽  
Jun-Sik Lim ◽  
Sun-Ah Song ◽  
Chiara Achangwa ◽  
Woobeom Sim ◽  
...  
Keyword(s):  
South Korea ◽  
Symptom Onset ◽  
Credible Interval ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Nasopharyngeal Swab ◽  
Strict Adherence ◽  
Virus Shedding ◽  
Viral Shedding ◽  
Asymptomatic Patients

Abstract Background The delta variant of SARS-CoV-2 is now the predominant variant worldwide. However, its transmission dynamics remain unclear. Methods We analyzed all case patients in local clusters and temporal patterns of viral shedding using contact tracing data from 405 cases associated with the delta variant of SARS-CoV-2 between 22 June and 31 July 2021 in Daejeon, South Korea. Results Overall, half of the cases were aged under 19 years, and 20% were asymptomatic at the time of epidemiological investigation. We estimated the mean serial interval as 3.26 days (95% credible interval 2.92, 3.60), and 12% of the transmission occurred before symptom onset of the infector. We identified six clustered outbreaks, and all were associated with indoor facilities. In 23 household contacts, the secondary attack rate was 63% (52/82). We estimated that 15% (95% confidence interval, 13–18%) of cases seeded 80% of all local transmission. Analysis of the nasopharyngeal swab samples identified virus shedding from asymptomatic patients, and the highest viral load was observed two days after symptom onset. The temporal pattern of viral shedding did not differ between children and adults (P = 0.48). Conclusions Our findings suggest that the delta variant is highly transmissible in indoor settings and households. Rapid contact tracing, isolation of the asymptomatic contacts, and strict adherence to public health measures are needed to mitigate the community transmission of the delta variant.

scholarly journals Calibrating an SIR model for South Korea COVID-19 infections and predicting vaccination impact

2021 ◽  
Author(s):  
Brandon Pae
Keyword(s):  
South Korea ◽  
Vaccination Coverage ◽  
Herd Immunity ◽  
Sir Model ◽  
Transmission Dynamics ◽  
Effective Vaccine ◽  
Epidemiological Models ◽  
Policy Decisions

In the span of 1.5 years, COVID-19 has caused more than 4 million deaths worldwide. To prevent such a catastrophe from reoccurring, it is necessary to test and refine current epidemiological models that impact policy decisions. Thus, we developed a deterministic SIR model to examine the long-term transmission dynamics of COVID-19 in South Korea. Using this model, we analyzed how vaccines would affect the number of cases. We found that a 70% vaccination coverage with a 100% effective vaccine would effectively eliminate the number of cases and herd immunity would have been obtained approximately 85 days after February 15 had there not been a reintroduction of cases.

scholarly journals Serial Interval and Transmission Dynamics during SARS-CoV-2 Delta Variant Predominance, South Korea

2022 ◽  
Vol 28 (2) ◽  
Author(s):  
Sukhyun Ryu ◽  
Dasom Kim ◽  
Jun-Sik Lim ◽  
Sheikh Taslim Ali ◽  
Benjamin J. Cowling
Keyword(s):  
South Korea ◽  
Transmission Dynamics ◽  
Serial Interval

scholarly journals Understanding Epidemic Data and Statistics: A Case Study of COVID-19

2020 ◽  
Author(s):  
Amirhoshang Hoseinpour Dehkordi ◽  
Majid Alizadeh ◽  
Pegah Derakhshan ◽  
Peyman Babazadeh ◽  
Arash Jahandideh
Keyword(s):  
South Korea ◽  
Case Fatality Rate ◽  
Case Fatality ◽  
Working Hours ◽  
Daily Basis ◽  
Transmission Dynamics ◽  
Fatality Rate ◽  
Mild Case ◽  
Novel Coronavirus

AbstractThe 2019-Novel-Coronavirus (COVID-19) has affected 181 countries and out of about 1197405 confirmed cases (By April 5). Understanding the transmission dynamics of the infection in each country which affected on a daily basis and evaluating the effectiveness of control policies is critical for our further actions. To date, the statistics of COVID-19 reported cases show more than 80 percent of infected had a mild case of disease, while around 14 percent of infected experienced a severe one and about 5 percent are categorized as critical disease victims. Today’s report (2020-04-05; daily updates in the prepared website) shows the confirmed cases of COVID-19 in US, Spain, Italy, and Germany are 308850, 126168, 124632 and 96092; respectively. Calculating the total Case Fatality Rate (CFR) of Italy (2020-04-04), about 13.3% of confirmed cases passed away. Compared to South Korea’s rate of 1.8% (7 times lower than Italy) and China’s 4% (69% lower than Italy), the CFR of Italy is too high. There are some effective policies that yield significant changes in the trend of cases. The lockdown policy in China, Italy and Spain (the effect observed after some days), Shutdown of all non-essential companies in Hubei (the effect observed after 5 days), combined policy in South Korea and reducing working hours in Iran.

scholarly journals Evolving Transmission Network Dynamics of COVID-19 Cluster Infections in South Korea: a descriptive study

2020 ◽  
Author(s):  
Yejin Kim ◽  
Xiaoqian Jiang
Keyword(s):  
Older Adults ◽  
Nursing Home ◽  
South Korea ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Transmission Network ◽  
Middle Aged ◽  
Reproduction Numbers ◽  
Path Lengths ◽  
Middle Aged Adults

AbstractBackgroundExtensive contact tracing and testing in South Korea allows us to investigate the transmission dynamics of the COVID-19 into diverse local communities.ObjectiveUnderstand the critical aspects of transmission dynamics in a different age, sex, and clusters with various activities.MethodsWe conducted a retrospective observational study with 3,127 confirmed cases’ contact tracing data from the Center for Disease and Prevention (CDC) of South Korea. We investigated network property concerning infected persons’ demographics and different infection clusters.FindingsOverall, women had higher centrality scores than men after week four, when the confirmed cases rapidly increased. Older adults have higher centrality than young/middle-aged adults after week 9. In the infection clusters, young/middle-aged adults’ infection clusters (such as religious gatherings and gym facilities) have higher average path lengths and diameter than older adult’s nursing home infection clusters.InterpretationSome women had higher reproduction numbers and bridged successive transmission than men when the confirmed cases rapidly increased. Similarly, some older adults (who were not residents of nursing homes) had higher reproduction numbers and bridged successive transmission than young/middle-aged adults after the peak has passed. The young/middle-aged adults’ religious gatherings and group workout have caused long successive transmissions. In contrast, the older adults’ nursing homes were a small world where the transmissions within a few steps can reach out to many persons.FundingUT Startup award, UT STARs award, and Cancer Prevention Research in Texas, and National Institute of General Medical SciencesResearch in contextEvidence before this study:On May 1, 2020, PubMed query (“COVID-19” OR “SARS-nCoV-2” OR “novel coronavirus” OR “nCoV”) AND (“transmission network” OR “transmission dynamics” OR “transmission pattern” OR “centrality”) AND (“cluster” OR “community”) yield eight peer-reviewed papers. These papers have provided an evolving epidemiology and transmission dynamics via estimated reproduction number. However, most of them have focused on the entire system in one location and there was no comparison between transmission dynamics of different clusters.Added value of this study:This study, to the best of our knowledge, is the first to compare the transmission dynamics of different cluster infections. We present the transmission dynamic with varying levels of granularity: entire country vs cluster infections as a longitudinal view. From the whole country-level analysis, we found that females have higher centrality (degree or betweenness) than males. From the cluster infection view, we found that young/middle-aged adults’ infection clusters (such as religious gatherings and gym facilities) have higher average path lengths and diameter than older adult’s nursing home infection clusters.Implications of all the available evidence:This study sheds light on different transmission dynamics concerning demographics (age and sex) and diverse behavior in cluster infections. These findings are essential for planning tailored policies to diverse communities. Our analysis code is publicly available to adapt to newly reported cases.

scholarly journals Effectiveness of Intervention Strategies on MERS-CoV Transmission Dynamics in South Korea, 2015: Simulations on the Network Based on the Real-World Contact Data

2021 ◽  
Vol 18 (7) ◽  
pp. 3530
Author(s):  
Yunhwan Kim ◽  
Hohyung Ryu ◽  
Sunmi Lee
Keyword(s):  
South Korea ◽  
Real World ◽  
Intervention Strategies ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Agent Based ◽  
The Real ◽  
Scale Free ◽  
Contact Data

The MERS-CoV spread in South Korea in 2015 was not only the largest outbreak of MERS-CoV in the region other than the Middle East but also a historic epidemic in South Korea. Thus, investigation of the MERS-CoV transmission dynamics, especially by agent-based modeling, would be meaningful for devising intervention strategies for novel infectious diseases. In this study, an agent-based model on MERS-CoV transmission in South Korea in 2015 was built and analyzed. The prominent characteristic of this model was that it built the simulation environment based on the real-world contact tracing network, which can be characterized as being scale-free. In the simulations, we explored the effectiveness of three possible intervention scenarios; mass quarantine, isolation, and isolation combined with acquaintance quarantine. The differences in MERS-CoV transmission dynamics by the number of links of the index case agent were examined. The simulation results indicate that isolation combined with acquaintance quarantine is more effective than others, and they also suggest the key role of super-spreaders in MERS-CoV transmission.

scholarly journals Transmission dynamics and control of two epidemic waves of SARS-CoV-2 in South Korea

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sukhyun Ryu ◽  
Sheikh Taslim Ali ◽  
Eunbi Noh ◽  
Dasom Kim ◽  
Eric H. Y. Lau ◽  
...  
Keyword(s):  
South Korea ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Reproductive Number ◽  
Local Public Health ◽  
Social Distancing ◽  
Illness Onset ◽  
Sources Of Infection ◽  
The Impact ◽  
Epidemic Wave

Abstract Background After relaxing social distancing measures, South Korea experienced a resurgent second epidemic wave of coronavirus disease 2019 (COVID-19). In this study, we aimed to identify the transmission dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and assess the impact of COVID-19 case finding and contact tracing in each epidemic wave. Methods We collected data on COVID-19 cases published by local public health authorities in South Korea and divided the study into two epidemic periods (19 January–19 April 2020 for the first epidemic wave and 20 April–11 August 2020 for the second epidemic wave). To identify changes in the transmissibility of SARS-CoV-2, the daily effective reproductive number (Rt) was estimated using the illness onset of the cases. Furthermore, to identify the characteristics of each epidemic wave, frequencies of cluster types were measured, and age-specific transmission probability matrices and serial intervals were estimated. The proportion of asymptomatic cases and cases with unknown sources of infection were also estimated to assess the changes of infections identified as cases in each wave. Results In early May 2020, within 2-weeks of a relaxation in strict social distancing measures, Rt increased rapidly from 0.2 to 1.8 within a week and was around 1 until early July 2020. In both epidemic waves, the most frequent cluster types were religious-related activities and transmissions among the same age were more common. Furthermore, children were rarely infectors or infectees, and the mean serial intervals were similar (~ 3 days) in both waves. The proportion of asymptomatic cases at presentation increased from 22% (in the first wave) to 27% (in the second wave), while the cases with unknown sources of infection were similar in both waves (22 and 24%, respectively). Conclusions Our study shows that relaxing social distancing measures was associated with increased SARS-CoV-2 transmission despite rigorous case findings in South Korea. Along with social distancing measures, the enhanced contact tracing including asymptomatic cases could be an efficient approach to control further epidemic waves.

scholarly journals Transmission Dynamics and Control of Two Epidemic Waves of SARS-CoV-2 in South Korea

2021 ◽  
Author(s):  
Sukhyun Ryu ◽  
Sheikh Taslim Ali ◽  
Eunbi Noh ◽  
Dasom Kim ◽  
Eric H.Y. Lau ◽  
...  
Keyword(s):  
South Korea ◽  
Transmission Dynamics ◽  
Contact Tracing ◽  
Reproductive Number ◽  
Local Public Health ◽  
Social Distancing ◽  
Illness Onset ◽  
Sources Of Infection ◽  
The Impact ◽  
Epidemic Wave

Abstract Background: After relaxing social distancing measures, South Korea experienced a resurgent second epidemic wave of coronavirus disease 2019 (COVID-19). In this study, we aimed to identify the transmission dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and assess the impact of COVID-19 case finding and contact tracing in each epidemic wave.Methods: We collected data on COVID-19 cases published by local public health authorities in South Korea and divided the study into two epidemic periods (19 January–19 April 2020 for the first epidemic wave and 20 April–11 August 2020 for the second epidemic wave). To identify changes in the transmissibility of SARS-CoV-2, the daily effective reproductive number (Rt) was estimated using the illness onset of the cases. Furthermore, to identify the characteristics of each epidemic wave, frequencies of cluster types were measured, and age-specific transmission probability matrices and serial intervals were estimated. The proportion of asymptomatic cases and cases with unknown sources of infection were also estimated to assess the changes of infections identified as cases in each wave.Results: In early May 2020, within 2-weeks of a relaxation in strict social distancing measures, Rt increased rapidly from 0.2 to 1.8 within a week and was around 1 until early July 2020. In both epidemic waves, the most frequent cluster types were religious-related activities and transmissions among the same age were more common. Furthermore, children were rarely infectors or infectees, and the mean serial intervals were similar (~3 days) in both waves. The proportion of asymptomatic cases at presentation increased from 22% (in the first wave) to 27% (in the second wave), while the cases with unknown sources of infection were similar in both waves (22% and 24%, respectively).Conclusions: Our study shows that relaxing social distancing measures was associated with increased SARS-CoV-2 transmission despite rigorous case findings in South Korea. Along with social distancing measures, the enhanced contact tracing including asymptomatic cases could be an efficient approach to control further epidemic waves.

scholarly journals The Characteristics of Middle Eastern Respiratory Syndrome Coronavirus Transmission Dynamics in South Korea

2016 ◽  
Vol 7 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Yunhwan Kim ◽  
Sunmi Lee ◽  
Chaeshin Chu ◽  
Seoyun Choe ◽  
Saeme Hong ◽  
...  
Keyword(s):  
South Korea ◽  
Middle Eastern ◽  
Transmission Dynamics
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