Epidemiology and Health

COVID-19: Original Article

Direct indicators of social distancing effectiveness in COVID-19 outbreak stages: a correlational analysis of case contacts and population mobility in Korea: Sojin Choi, Chanhee Kim, Kun-Hee Park, Jong-Hun Kim; Epidemiol Health. 2023;45:e2023065. Published online July 10, 2023; DOI: https://doi.org/10.4178/epih.e2023065

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
The effectiveness of social distancing during the coronavirus disease 2019 (COVID-19) pandemic has been evaluated using the magnitude of changes in population mobility. This study aimed to investigate a direct indicator—namely, the number of close contacts per patient with confirmed COVID-19.
METHODS
From week 7, 2020 to week 43, 2021, population movement changes were calculated from the data of two Korean telecommunication companies and Google in accordance with social distancing stringency levels. Data on confirmed cases and their close contacts among residents of Gyeonggi Province, Korea were combined at each stage. Pearson correlation analysis was conducted to compare the movement data with the change in the number of contacts for each confirmed case calculated by stratification according to age group. The reference value of the population movement data was set using the value before mid-February 2020, considering each data’s characteristics.
RESULTS
In the age group of 18 or younger, the number of close contacts per confirmed case decreased or increased when the stringency level was strengthened or relaxed, respectively. In adults, the correlation was relatively low, with no correlation between the change in the number of close contacts per confirmed case and the change in population movement after the commencement of vaccination for adults.
CONCLUSIONS
The effectiveness of governmental social distancing policies against COVID-19 can be evaluated using the number of close contacts per confirmed case as a direct indicator, especially for each age group. Such an analysis can facilitate policy changes for specific groups.; Summary

Korean summary
1. 사회적 거리두기의 효과를 간접적인 자료인 이동통신사와 구글데이터를 이용하여 인구 이동성 변화의 크기를 평가하였고, 직접적인 자료인 역학조사서의 확진자 1인당 밀접 접촉자 수를 산출하여 비교 평가하였다. 2. 18세 이하 연령대는 사회적 거리두기의 강화 또는 완화 단계에 따라 확진자 1인당 밀접 접촉자 수가 민감하게 변동되었으나, 성인의 경우에는 덜 민감하게 변동되었다. 3. 역학조사서에 기반하여 시계열 자료로 재가공한 확진자 1인당 밀접 접촉자 수는 사회적 거리두기 정책의 효과를 평가하는 직접적인 평가 지표로 사용될 수 있기에 충분히 검토되어야 한다.

Key Message
1. The study assessed social distancing's effectiveness by analyzing population mobility changes through mobile operator and Google data. And it was also compared with the number of close contacts per confirmed COVID-19 case based on the epidemiological survey report. 2. Younger age groups were more influenced by the social distancing policy in close contacts per confirmed COVID-19 case than adults. 3. The study suggests using close contacts per confirmed COVID-19 case from the epidemiological survey report as a direct measure of social distancing policy effectiveness.

COVID-19: Epidemiologic Investigation

Experience of a COVID-19 outbreak response in a general hospital in Gyeonggi Province, Korea: Chanhee Kim, Gawon Choi, Shin Young Park, Jieun Kim, Young Joon Park, Kyungnam Kim; Epidemiol Health. 2021;43:e2021083. Published online October 18, 2021; DOI: https://doi.org/10.4178/epih.e2021083

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Abstract Summary PDF

Abstract

OBJECTIVES
Coronavirus disease 2019 (COVID-19) outbreaks in general hospitals are particularly risky because they not only overburden the regional healthcare delivery system, but also increase the possibility of community transmission. This study shares an experience of a COVID-19 outbreak response in a general hospital in Gyeonggi Province, Korea.

METHODS

Since the first COVID-19 confirmed case was recognized in Hospital A on March 29, 2020, the Immediate Response Team of Gyeonggi Province and Korea Disease Control and Prevention Agency devised a plan to conduct an epidemiological investigation and minimize the paralysis of hospital functions. Apart from the epidemiological investigation, a risk assessment of the hospital and management of contacts, including patients and workers, were also undertaken.

RESULTS

In total, 72 confirmed cases were identified, including 26 hospitalized patients, 16 healthcare personnel, 7 visitors, and 22 cases identified externally. The majority of the confirmed cases were exposed in Ward B or were contacts of people exposed in Ward A (58.3% of 72 cases). Among healthcare personnel, caregivers were found to be the most vulnerable to COVID-19 in this outbreak.

CONCLUSIONS

Preparation for all possible situations in medical facilities is important because it is difficult to find alternative resources. The findings of this study provide information on controlling the further transmission of COVID-19 and furnish evidence of the importance of ordinary management skills to be prepared for COVID-19.

Summary

Korean summary
본 연구에서는 2020년 경기도 소재 한 종합병원에서 발생한 코로나19 유행 대응 사례 경험을 공유한다. 병원 외 지역사회 전파 사례를 포함하여 총 72명의 확진자가 이 유행에서 확인되었다. 종합병원은 지역 의료전달체계에서 중요한 역할을 하고 있기 때문에 코로나19로 인해 그 기능이 마비되지 않도록 예방하는 것이 가장 바람직하며, 이를 위해서는 평상 시에 적절한 대비 체계를 갖추어 두어야 한다.

Key Message
This study shares the experience of responding to the COVID-19 outbreak at a general hospital in Gyeonggi-do, 2020. A total of 72 confirmed cases were identified, including cases of community based transmission outside the hospital. Since general hospitals play an important role in the medical delivery system, it is most desirable to prevent the function from being paralyzed by COVID-19 situation, and for this, and appropriate preparedness should be established.

Citations

Citations to this article as recorded by

Vaccine effectiveness and the epidemiological characteristics of a COVID-19 outbreak in a tertiary hospital in Republic of Korea
Seonhee Ahn, Tae Jong Son, Yoonsuk Jang, Jihyun Choi, Young Joon Park, Jiseon Seong, Hyun Hee Kwon, Muk Ju Kim, Donghyok Kwon
Osong Public Health and Research Perspectives.2023; 14(3): 188. CrossRef
Effect of changes in the hearing aid subsidy on the prevalence of hearing loss in South Korea
Chul Young Yoon, Junhun Lee, Tae Hoon Kong, Young Joon Seo
Frontiers in Neurology.2023;[Epub] CrossRef

COVID-19: Epidemiologic Investigation

COVID-19 outbreak in a military unit in Korea: Chanhee Kim, Young-Man Kim, Namwoo Heo, Eunjung Park, Sojin Choi, Sehyuk Jang, Nayoung Kim, Donghyok Kwon, Young-Joon Park, Byeongseop Choi, Beomman Ha, Kyounghwa Jung, Changbo Park, Sejin Park, Heeyoung Lee; Epidemiol Health. 2021;43:e2021065. Published online September 8, 2021; DOI: https://doi.org/10.4178/epih.e2021065

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Abstract Summary PDF

Abstract

OBJECTIVES
This study presents the response of a military unit to an outbreak of coronavirus disease 2019 (COVID-19) in Gyeonggi Province. As soon as 2 soldiers were identified as index cases, the infectious disease investigators of the Gyeonggi Provincial Government, Korea Disease Control and Prevention Agency, and the Armed Forces Epidemiologic Investigation Center discussed the investigation and response plan for an imminent massive outbreak.

METHODS

The joint immediate response team (IRT) conducted interviews with confirmed COVID-19 patients, reviewed their medical records, performed contact tracing using global positioning system data, and undertook a field investigation. For risk assessment, the joint IRT visited all 8 sites of the military units and the army chaplain’s church to evaluate the transmission risk at each site. The evaluation items included the size of the site, the use of air conditioning, whether windows were opened, and whether masks were worn. Pooled testing was used for the low-risk population to quickly detect the spread of COVID-19 in the military base.

RESULTS

One day before the symptom onset of the index case, the lecturer and >50% of the attendees were infected with COVID-19 while attending a lecture that lasted 2 hours and 30 minutes. Attendees were not wearing masks and were in a poorly ventilated room.

CONCLUSIONS

Since COVID-19 can be spread before symptom onset, contact tracing must be performed to investigate potential exposures prior to symptom onset and to manage any exposed persons.

Summary

Korean summary
본 연구는 경기도 군부대에서 발생한 코로나19 대응 경험을 공유하는 국내 최초의 연구 결과이다. 본 연구를 통해 정리된 역학조사 과정은 군부대, 기숙사, 교정시설 등 집단 시설의 방역 대책 수립에 도움이 될 것으로 기대한다. 또한, 이번 사례는 집단 감염 발생 시 여러 유관 기관의 협조 체계가 신속한 대응과 추가 전파 예방에 중요하다는 점을 시사한다.

Key Message
This study is the first research in South Korea to share the experience of responding to COVID-19 at the military unit in Gyeonggi-do. The epidemiological investigation process organized through this study is expected to help establish response measures for group facilities such as military units, dormitories, and correctional facilities. In addition, this case suggests that the cooperative system of various related organizations in the event of a mass infection is important for rapid response and prevention of further transmission.

Citations

Citations to this article as recorded by

Evaluation of diagnostic performance of SARS-CoV-2 infection using digital droplet polymerase chain reaction in individuals with or without COVID-19 symptoms
Yoonjung Kim, Eunyoung Lee, Boyeon Kim, Jinhee Cho, Sook-Won Ryu, Kyung-A Lee
Clinica Chimica Acta.2024; 554: 117759. CrossRef
Trends in Confirmed COVID-19 Cases in the Korean Military Before and After the Emergence of the Omicron Variant
Dong Hoon Shin, Haebong Jang, Sangho Lee, Byung Seop Choi, Donghoon Kim, Hong Sang Oh
Journal of Korean Medical Science.2022;[Epub] CrossRef
Characteristics of COVID-19 outbreaks and risk factors for transmission at an army training center in South Korea from June to August 2021
U Jin Cho, Seongjin Wang, Seonju Yi, Yeon Hwa Choi, Eun-Young Kim, Jin A Kim, Sanghwan Bae, Jungyeon Yu, Jangkyu Choi, Young-Joon Park
Osong Public Health and Research Perspectives.2022; 13(4): 263. CrossRef

Original Article

Recent increase in pertussis incidence in Korea: an age-period-cohort analysis: Chanhee Kim, Seonju Yi, Sung-il Cho; Epidemiol Health. 2021;43:e2021053. Published online August 18, 2021; DOI: https://doi.org/10.4178/epih.e2021053

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Abstract Summary PDF Supplementary Material

Abstract

OBJECTIVES
Pertussis or whooping cough—one of the most contagious diseases—is caused by the Gram-negative bacterium <i>Bordetella pertussis</i>. Despite a high vaccination rate, Korea recently experienced a resurgence of pertussis. This study explores patterns and possible explanations for this resurgence through an age-period-cohort analysis.

METHODS

Using secondary data from the infectious disease portal of the Korea Disease Control and Prevention Agency and the Korea Statistical Information Service of Statistics Korea, this study analyzed the incidence of pertussis in Korea to determine which factors contributed to the recent increase using an age-period-cohort model.

RESULTS

Analysis of the age effect indicated that the age group most vulnerable to pertussis was 0-year to 2-year-olds. Analysis of the period effect showed a sharp increase in the incidence rate after 2016. Analysis of the cohort effect showed a significant decrease in incidence beginning with the 1955 birth cohort, with the risk increasing again with the 2000s birth cohort.

CONCLUSIONS

Previous studies have suggested 3 main possible explanations for our results. First, the increased incidence rate can be attributed to contact rates. Second, the rate of immunity through natural exposure has decreased due to the low number of circulating pathogens, in turn affecting the trend of infection. Lastly, variations in pathogens may have also contributed to the increase in incidence. Given that the most significant increase in incidence was observed among infants younger than 1 year old, sufficient maternal immunity must be prioritized to provide passive immunity to newborns via the placenta.

Summary

Korean summary
본 연구는 연령-기간-코호트 모델을 활용하여 예방접종률이 높은 국가들의 백일해 재출현에 기여하는 요인에 무엇이 있는지 살펴보았다. 연령에 따른 사회적 접촉률(contact rate)의 변화, 자연노출에 의한 면역 강화(natural boosting) 기회의 감소, 그리고 백일해 병원체의 변이가 백일해 재출현의 원인일 수 있다. 분석 결과 영아 집단에서 백일해 발병률이 가장 급격한 증가가 관찰되었으며, 이는 모성면역의 확보가 중요하다는 점을 시사한다.

Key Message
This study examined factors contribute to the re-emergence of pertussis in countries with high vaccination rates using the age-period-cohort model. Changes in social contact rates according to age, reduction in immune boosting opportunities by natural exposure, and variations in pertussis pathogens may be the cause of re-emergence. As a result of the analysis, the sharpest increase in the incidence of pertussis in the infant group was observed, suggesting that securing maternal immunity is important.

Citations

Citations to this article as recorded by

Epidemiological Characteristics of Notifiable Respiratory Infectious Diseases in Mainland China from 2010 to 2018
Lele Deng, Yajun Han, Jinlong Wang, Haican Liu, Guilian Li, Dayan Wang, Guangxue He
International Journal of Environmental Research and Public Health.2023; 20(5): 3946. CrossRef
Incidence and Healthcare Burden of Pertussis among Older Adults with and without Pre-Existing Chronic Obstructive Pulmonary Disease or Asthma in South Korea
Jing Chen, Ju-Young Shin, Hyungwoo Kim, Ju Hwan Kim, Ahhyung Choi, Hee Jin Cheong, Yeon-Mok Oh, Adrienne Guignard, Sumitra Shantakumar
COPD: Journal of Chronic Obstructive Pulmonary Disease.2023; 20(1): 126. CrossRef
Pre-Pandemic Distribution of Bacterial Species in Nasopharyngeal Swab Specimens from Pediatric and Adult Patients Detected via RT-PCR Using the Allplex Respiratory Panel
Dong-Hyun Lee, Young-Jin Choi, Jieun Kim, Eunhee Han, Mi-Hyun Bae
Life.2023; 13(9): 1840. CrossRef
Bacterial Etiology in Subacute Cough
Ji-Yong Moon, Hyun Lee, Min-Hye Kim, Woo-Jung Song, Sang Min Lee, Sae-Hoon Kim, Sang-Heon Kim, Byung-Jae Lee, Ho Joo Yoon, Sang Hoon Kim
Allergy, Asthma & Immunology Research.2023; 15(5): 673. CrossRef
Post-Marketing Surveillance of Tetravalent Diphtheria-Tetanus-Acellular Pertussis and Inactivated Poliovirus (DTaP-IPV) Vaccine in South Korea, 2009 to 2015
Young June Choe, Emmanuel Vidor, Christine Manson
Infectious Diseases and Therapy.2022; 11(4): 1479. CrossRef
ARIMA and ARIMA-ERNN models for prediction of pertussis incidence in mainland China from 2004 to 2021
Meng Wang, Jinhua Pan, Xinghui Li, Mengying Li, Zhixi Liu, Qi Zhao, Linyun Luo, Haiping Chen, Sirui Chen, Feng Jiang, Liping Zhang, Weibing Wang, Ying Wang
BMC Public Health.2022;[Epub] CrossRef
Evaluation of Whole-Cell and Acellular Pertussis Vaccines in the Context of Long-Term Herd Immunity
Ewa Szwejser-Zawislak, Mieszko M. Wilk, Piotr Piszczek, Justyna Krawczyk, Daria Wilczyńska, Daniela Hozbor
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