scholarly journals Response to COVID-19 in South Korea and implications for lifting stringent interventions

BMC Medicine ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Amy Dighe ◽  
Lorenzo Cattarino ◽  
Gina Cuomo-Dannenburg ◽  
Janetta Skarp ◽  
Natsuko Imai ◽  
...  
Keyword(s):  
South Korea ◽  
High Volume ◽  
Individual Case ◽  
Metropolitan Region ◽  
Contact Tracing ◽  
Social Distancing ◽  
Early Adoption ◽  
The Usa ◽  
Sharp Growth ◽  
Seoul Metropolitan Region

Abstract Background After experiencing a sharp growth in COVID-19 cases early in the pandemic, South Korea rapidly controlled transmission while implementing less stringent national social distancing measures than countries in Europe and the USA. This has led to substantial interest in their “test, trace, isolate” strategy. However, it is important to understand the epidemiological peculiarities of South Korea’s outbreak and characterise their response before attempting to emulate these measures elsewhere. Methods We systematically extracted numbers of suspected cases tested, PCR-confirmed cases, deaths, isolated confirmed cases, and numbers of confirmed cases with an identified epidemiological link from publicly available data. We estimated the time-varying reproduction number, Rt, using an established Bayesian framework, and reviewed the package of interventions implemented by South Korea using our extracted data, plus published literature and government sources. Results We estimated that after the initial rapid growth in cases, Rt dropped below one in early April before increasing to a maximum of 1.94 (95%CrI, 1.64–2.27) in May following outbreaks in Seoul Metropolitan Region. By mid-June, Rt was back below one where it remained until the end of our study (July 13th). Despite less stringent “lockdown” measures, strong social distancing measures were implemented in high-incidence areas and studies measured a considerable national decrease in movement in late February. Testing the capacity was swiftly increased, and protocols were in place to isolate suspected and confirmed cases quickly; however, we could not estimate the delay to isolation using our data. Accounting for just 10% of cases, individual case-based contact tracing picked up a relatively minor proportion of total cases, with cluster investigations accounting for 66%. Conclusions Whilst early adoption of testing and contact tracing is likely to be important for South Korea’s successful outbreak control, other factors including regional implementation of strong social distancing measures likely also contributed. The high volume of testing and the low number of deaths suggest that South Korea experienced a small epidemic relative to other countries. Caution is needed in attempting to replicate the South Korean response in populations with larger more geographically widespread epidemics where finding, testing, and isolating cases that are linked to clusters may be more difficult.

scholarly journals Estimating the effectiveness of non-pharmaceutical interventions on COVID-19 control in South Korea

2020 ◽  
Author(s):  
Kyung-Duk Min ◽  
Heewon Kang ◽  
Ju-Yeun Lee ◽  
Seonghee Jeon ◽  
Sung-il Cho
Keyword(s):  
South Korea ◽  
Compartment Model ◽  
Contact Tracing ◽  
Contact Rate ◽  
Global Public Health ◽  
Spring Semester ◽  
Detection Rates ◽  
Social Distancing ◽  
Effective Contact ◽  
Pharmaceutical Interventions

Abstract Background: The coronavirus disease 2019 (COVID-19) pandemic has posed significant global public health challenges and created a substantial economic burden. South Korea has experienced an extensive outbreak, which was linked to a religion-related super-spreading event. However, the implementation of various non-pharmaceutical interventions (NPIs), including social distancing, spring semester postponing, and extensive testing and contact tracing controlled the epidemic. Herein, we estimated the effectiveness of each NPI using a simulation model.Methods: A compartment model with a susceptible-exposed-infectious-quarantined-hospitalized (SEIQH) structure was employed. Using the Monte-Carlo-Markov-Chain algorithm with Gibbs’ sampling method, we estimated the time-varying effective contact rate to calibrate the model with the reported daily new confirmed cases from February 12th to March 31st (7 weeks). Moreover, we conducted scenario analyses by adjusting the parameters to estimate the effectiveness of NPI.Results: Relaxed social distancing among adults would have increased the number of cases 27-fold until the end of March, and the epidemic curve would have been similar to other high burden countries. Spring semester non-postponement would have increased the effective contact rate 2·4-fold among individuals aged 0-19, while lower quarantine and detection rates would have increased the number of cases 1·4-fold. Conclusions: Among the three NPI measures, social distancing in adults showed the highest effectiveness. The substantial effect of social distancing should be considered for developing an exit strategy.

scholarly journals Nationwide Results of COVID-19 Contact Tracing in South Korea: Individual Participant Data From an Epidemiological Survey (Preprint)

2020 ◽  
Author(s):  
Seung Won Lee ◽  
Woon Tak Yuh ◽  
Jee Myung Yang ◽  
Yoon-Sik Cho ◽  
In Kyung Yoo ◽  
...  
Keyword(s):  
Mortality Rate ◽  
South Korea ◽  
Long Term Care ◽  
Contact Tracing ◽  
Term Care ◽  
Social Distancing ◽  
Percentage Difference ◽  
Care Facilities ◽  
Epidemiological Characteristics

BACKGROUND Evidence regarding the effectiveness of contact tracing of COVID-19 and the related social distancing is limited and inconclusive. OBJECTIVE This study aims to investigate the epidemiological characteristics of SARS-CoV-2 transmission in South Korea and evaluate whether a social distancing campaign is effective in mitigating the spread of COVID-19. METHODS We used contract tracing data to investigate the epidemic characteristics of SARS-CoV-2 transmission in South Korea and evaluate whether a social distancing campaign was effective in mitigating the spread of COVID-19. We calculated the mortality rate for COVID-19 by infection type (cluster vs noncluster) and tested whether new confirmed COVID-19 trends changed after a social distancing campaign. RESULTS There were 2537 patients with confirmed COVID-19 who completed the epidemiologic survey: 1305 (51.4%) cluster cases and 1232 (48.6%) noncluster cases. The mortality rate was significantly higher in cluster cases linked to medical facilities (11/143, 7.70% vs 5/1232, 0.41%; adjusted percentage difference 7.99%; 95% CI 5.83 to 10.14) and long-term care facilities (19/221, 8.60% vs 5/1232, 0.41%; adjusted percentage difference 7.56%; 95% CI 5.66 to 9.47) than in noncluster cases. The change in trends of newly confirmed COVID-19 cases before and after the social distancing campaign was significantly negative in the entire cohort (adjusted trend difference –2.28; 95% CI –3.88 to –0.68) and the cluster infection group (adjusted trend difference –0.96; 95% CI –1.83 to –0.09). CONCLUSIONS In a nationwide contact tracing study in South Korea, COVID-19 linked to medical and long-term care facilities significantly increased the risk of mortality compared to noncluster COVID-19. A social distancing campaign decreased the spread of COVID-19 in South Korea and differentially affected cluster infections of SARS-CoV-2.

scholarly journals Nationwide Results of COVID-19 Contact Tracing in South Korea: Individual Participant Data From an Epidemiological Survey

10.2196/20992 ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. e20992 ◽  
Author(s):  
Seung Won Lee ◽  
Woon Tak Yuh ◽  
Jee Myung Yang ◽  
Yoon-Sik Cho ◽  
In Kyung Yoo ◽  
...  
Keyword(s):  
Mortality Rate ◽  
South Korea ◽  
Long Term Care ◽  
Contact Tracing ◽  
Term Care ◽  
Social Distancing ◽  
Percentage Difference ◽  
Care Facilities ◽  
Epidemiological Characteristics

Background Evidence regarding the effectiveness of contact tracing of COVID-19 and the related social distancing is limited and inconclusive. Objective This study aims to investigate the epidemiological characteristics of SARS-CoV-2 transmission in South Korea and evaluate whether a social distancing campaign is effective in mitigating the spread of COVID-19. Methods We used contract tracing data to investigate the epidemic characteristics of SARS-CoV-2 transmission in South Korea and evaluate whether a social distancing campaign was effective in mitigating the spread of COVID-19. We calculated the mortality rate for COVID-19 by infection type (cluster vs noncluster) and tested whether new confirmed COVID-19 trends changed after a social distancing campaign. Results There were 2537 patients with confirmed COVID-19 who completed the epidemiologic survey: 1305 (51.4%) cluster cases and 1232 (48.6%) noncluster cases. The mortality rate was significantly higher in cluster cases linked to medical facilities (11/143, 7.70% vs 5/1232, 0.41%; adjusted percentage difference 7.99%; 95% CI 5.83 to 10.14) and long-term care facilities (19/221, 8.60% vs 5/1232, 0.41%; adjusted percentage difference 7.56%; 95% CI 5.66 to 9.47) than in noncluster cases. The change in trends of newly confirmed COVID-19 cases before and after the social distancing campaign was significantly negative in the entire cohort (adjusted trend difference –2.28; 95% CI –3.88 to –0.68) and the cluster infection group (adjusted trend difference –0.96; 95% CI –1.83 to –0.09). Conclusions In a nationwide contact tracing study in South Korea, COVID-19 linked to medical and long-term care facilities significantly increased the risk of mortality compared to noncluster COVID-19. A social distancing campaign decreased the spread of COVID-19 in South Korea and differentially affected cluster infections of SARS-CoV-2.

scholarly journals Riding the waves of the COVID-19 pandemic in South Korea

2021 ◽  
Vol 13 (2) ◽  
pp. 116
Author(s):  
Joseph Christian Obnial ◽  
Maria Beatriz Baron ◽  
Hannah Andrea Sagsagat ◽  
Erika Ong ◽  
Ma. Alexandra Nicola Valenzuela ◽  
...  
Keyword(s):  
South Korea ◽  
Disease Transmission ◽  
Economic Consequences ◽  
Contact Tracing ◽  
Social Distancing ◽  
Korean Government ◽  
The Waves

ABSTRACT During the first months of the coronavirus disease 2019 (COVID-19) pandemic in early 2020, South Korea stood as one of the most successful in preventing a nationwide outbreak. The country was unique in that it did so without enforcing massive border restrictions and tight social distancing measures, instead focusing on maximal testing, contact tracing, and treatment. But as the year 2020 went on, the country has suffered second and third waves, each one being larger and harder to combat than the last. The Korean government, however, has been unwilling to impose stringent measures due to potential economic consequences and has still relied on its initial strategies in an attempt to prevent further disease transmission. It is therefore crucial to revisit their position beyond their early successes to re-evaluate the effectiveness of their strategy, and to finally decide if it is time to move on to more drastic measures.

scholarly journals Boundary layer pollution profiles from a rural site in South Korea

2018 ◽  
Vol 176 ◽  
pp. 04004
Author(s):  
John Sullivan ◽  
Thomas McGee ◽  
Anne Thompson ◽  
Laurence Twigg ◽  
Grant Sumnicht ◽  
...  
Keyword(s):  
Boundary Layer ◽  
South Korea ◽  
Metropolitan Region ◽  
Rural Site ◽  
Forest Site ◽  
Seoul Metropolitan Region

During the NASA 2016 KORUS-AQ campaign, the ground based NASA GSFC ozone lidar and balloon borne instrumentation were deployed to the remote Taehwa Forest site (37.3 N, 127.3 E, 151 m AGL) to characterize the transport of pollution downwind of the Seoul metropolitan region. On most days from 02 May to 10 June 2016, continuous hours of lidar profiles of ozone were measured. Select days are shown to represent key ozone events that occurred at the rural site.

scholarly journals Social Distancing and Outdoor Physical Activity During the COVID-19 Outbreak in South Korea: Implications for Physical Distancing Strategies

2020 ◽  
Vol 32 (6-7) ◽  
pp. 360-362 ◽  
Author(s):  
Sunhee Park ◽  
Beomsoo Kim ◽  
Jaeil Lee
Keyword(s):  
Physical Activity ◽  
South Korea ◽  
Surface Cleaning ◽  
Contact Tracing ◽  
Social Distancing ◽  
The Public ◽  
Positive Effects ◽  
The Social ◽  
Novel Coronavirus ◽  
Bicycle Sharing System

The novel coronavirus disease (COVID-19) outbreak has put the entire world in a pandemic situation. In response, strict screening, quarantine protocols, and contact tracing have been conducted in South Korea. The purpose of this study was to examine effects of social distancing on the Public Bicycle Sharing System (PBSS) during the COVID-19 outbreak. We used the PBSS public dataset of Seoul, South Korea. Difference-in-differences (DID) analysis was used. In the DID approach, the 2 groups are distinguished based on designated year. Cases of PBSS use were observed in 2 time periods: pre- and post-strict social distancing in Seoul, Korea. Average PBSS usage per day doubled during 2019-2020 (30 697 vs 77 996, P < .001). Commuters and weekend users increased during the social distancing period in 2020 compared with the same period in 2019. DID analysis showed statistically significant positive effects of high levels of social distancing on PBSS usage, commuters, weekend users, and new subscribers. In conclusion, social distancing during the COVID-19 outbreak increased outdoor physical activity. Meaningful outdoor physical activity during the COVID-19 pandemic can be safe from infection and psychologically stabilized as long as keeping meticulous physical distancing, such as hand hygiene, wearing facial masks, and surface cleaning of public resources.

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 Initial Model for USA CoVID-19 Resurgence

2020 ◽  
Author(s):  
Genghmun Eng
Keyword(s):  
South Korea ◽  
Linear Function ◽  
Doubling Time ◽  
Functional Form ◽  
Gradual Increase ◽  
Initial Model ◽  
Social Distancing ◽  
Daily Number ◽  
The Usa

Early CoVID-19 growth obeys: N{t*}=NI exp[+Ko t* ], with Ko=[(ln2)/(tdbl)], where tdbl is the pandemic growth doubling time. Given N{t*}, the daily number of new CoVID-19 cases is ρ{t*} = dN{t*}/d{t*}. Implementing society-wide Social Distancing increases the tdbl doubling time, and a linear function of time for tdbl was used in our Initial Model: No[t] = 1 exp[+KA t / (1 + γot) ] = eGo exp(-Zo[t] ) , to describe these changes, where the [t]-axis is time-shifted from the t*-axis, back to the pandemic start, and Go = [ KA / γo ]. While this No[t] successfully modeled the USA CoVID-19 progress from 3/2020 to 6/2020, this equation could not easily model some quickly decreasing ρ[t] cases ("fast pandemic shutoff"), indicating that a second process was involved. This situation was most evident in the initial CoVID-19 data from China, South Korea, and Italy. Modifying Zo[t] to allow exponential cutoffs: Zo[t] ≡ +[Go / (1+γot)] [exp(-δot)] = Zo[t] exp(-δot) , NA[t] = eGo exp(-ZA[t]) , resulted in an Enhanced Initial Model (EIM) that significantly improved data fits for these cases. After 6/2020, many regions of the USA "opened up", loosening their Social Distancing requirements, which led to a sudden USA CoVID-19 Resurgence. Extrapolating the USA No[t] 3/2020-6/2020 results to 9/2020 as an Initial Model Baseline (IMB), and subtracting this IMB from the newer USA data gives a Resurgence Only function, which is analyzed here. This USA CoVID-19 Resurgence function differs significantly from the No[t] IMB functional form, but it was well-modeled by the NA[t] fast pandemic shutoff function. These results indicate that: (a) the gradual increase in tdbl doubling time from society-wide shut-downs is likely due to eliminating of a large number of population gathering points that could have enabled CoVID-19 spread; and (b) having a non-zero δofast pandemic shutoff is likely due to more people wearing masks more often [with 12 Figures].

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