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Original Articles
Epidemiological characteristics of varicella outbreaks in the Republic of Korea, 2016–2020
Eun-Young Kim, Chungmin Park, Gyehee Lee, Suyeon Jeong, Jeongsuk Song, Dong-Han Lee
Osong Public Health Res Perspect. 2022;13(2):133-141.   Published online April 26, 2022
DOI: https://doi.org/10.24171/j.phrp.2022.0087
  • 435 View
  • 31 Download
AbstractAbstract PDF
Objectives
We described the trends and epidemiological characteristics of varicella outbreaks from 2016 to 2020 in the Republic of Korea. Methods: We investigated variables such as the outbreak setting, age of patients, vaccination status, and lesion count. The collected data were analyzed with the Cochrane-Armitage trend test and Kruskal-Wallis test. These statistical tests were performed using R ver. 4.0.3. Results: The number of varicella outbreaks increased from 2016 to 2018; however, after a slight decrease in the number of outbreaks in 2019, the number fell sharply in 2020. The median size of outbreaks decreased from 8 to 9 cases during 2016−2019 to 6 cases in 2020. The median duration of outbreaks was 18 days during 2016−2017, 28 days in 2018, 29 days in 2019, and 15 days in 2020. Varicella outbreaks occurred most frequently in elementary schools, and vaccination coverage of patients increased from 89.4% in 2016 to 97.2% in 2019. The median age of patients with outbreak-related varicella decreased from 8 years in 2016 to 6 years in 2020. Conclusion: Significant changes were observed in the age of patients with outbreak-related varicella. Ongoing monitoring of varicella outbreaks should be conducted. Further research will be needed to measure the disease burden of varicella and enable evidence-based policy decisions.
COVID-19 outbreak response at a nursing hospital in South Korea in the post-vaccination era, including an estimation of the effectiveness of the first shot of the Oxford-AstraZeneca COVID-19 vaccine (ChAdOx1-S)
Chanhee Kim, Geon Kang, Sun Gu Kang, Heeyoung Lee
Osong Public Health Res Perspect. 2022;13(2):114-122.   Published online April 26, 2022
DOI: https://doi.org/10.24171/j.phrp.2021.0262
  • 1,017 View
  • 51 Download
AbstractAbstract PDF
Objectives
We descriptively reviewed a coronavirus disease 2019 (COVID-19) outbreak at a nursing hospital in Gyeonggi Province (South Korea) and assessed the effectiveness of the first dose of the Oxford-AstraZeneca vaccine in a real-world population. Methods: The general process of the epidemiological investigation included a public health intervention. The relative risk (RR) of vaccinated and unvaccinated groups was calculated and compared to confirm the risk of severe acute respiratory syndrome coronavirus-2 (SARSCoV-2) infection, and vaccine effectiveness was evaluated based on the calculated RR. Results: The population at risk was confined to ward E among 8 wards of Hospital X, where the outbreak occurred. This population comprised 55 people, including 39 patients, 12 nurses, and 4 caregivers, and 19 cases were identified. The RR between the vaccinated and unvaccinated groups was 0.04, resulting in a vaccine effectiveness of 95.3%. The vaccination rate of the nonpatients in ward E was the lowest in the entire hospital, whereas the overall vaccination rate of the combined patient and non-patient groups in ward E was the third lowest. Conclusion: The first dose of the Oxford-AstraZeneca vaccine (ChAdOx1-S) was effective in preventing SARS-CoV-2 infection. To prevent COVID-19 outbreaks in medical facilities, it is important to prioritize the vaccination of healthcare providers.
Short Communication
COVID-19 outbreak and risk factors for infection in a taekwondo gym in the Republic of Korea
Seung Hwan Shin, Eonjoo Park, Sookhyun Kim, Minji Jang, Subin Park, Dong-Hwi Kim, Tae Jong Son, Ji-Hyuk Park
Osong Public Health Res Perspect. 2022;13(2):162-170.   Published online March 31, 2022
DOI: https://doi.org/10.24171/j.phrp.2021.0295
  • 644 View
  • 45 Download
AbstractAbstract PDF
Objectives
Relatively few studies have assessed risk factors for coronavirus disease 2019 (COVID-19) in public facilities used by children and adolescents. This study presents an analysis of a COVID-19 outbreak that occurred in a taekwondo gym in Korea, predominantly among children and adolescents, with the aim of providing insights on managing COVID-19 outbreaks in similar facilities. Methods: All 108 taekwondo gym students and staff received COVID-19 tests. A survey and closed-circuit television analyses were used to identify risk factors. A univariate analysis was conducted, followed by multivariate logistic regression analysis with backward elimination for variables with a significance level <0.10 in the univariate analysis. Results: COVID-19 was confirmed in 30 of 108 subjects at the taekwondo gym (attack rate, 27.8%). The outbreak started in an adult class student. This student transmitted the virus to the staff, who consequently transmitted the virus to adolescent students. In the univariate analysis, the relative risk for younger age (≤9 years) was 2.14 (95% confidence interval [CI], 1.01–4.54; p=0.054), and that for food consumption inside the gym was 2.12 (95% CI, 1.04–4.30; p=0.048). In the multivariate logistic regression analysis, the odds ratio for younger age was 2.96 (95% CI, 1.07–8.20; p=0.036), and that for food consumption inside the gym was 3.00 (95% CI, 1.10–8.17; p=0.032). Conclusion: Food consumption inside the facility and young age were significant risk factors for COVID-19 transmission in this taekwondo gym. Food consumption should be prohibited in sports facilities, and infection prevention education for young students is also required.
Original Articles
Delays in the diagnosis and treatment of tuberculosis during the COVID-19 outbreak in the Republic of Korea in 2020
Jiyeon Yang, Yunhyung Kwon, Jaetae Kim, Yoojin Jang, Jiyeon Han, Daae Kim, Hyeran Jeong, Hyekyung Park, Eunhye Shim
Osong Public Health Res Perspect. 2021;12(5):293-303.   Published online September 23, 2021
DOI: https://doi.org/10.24171/j.phrp.2021.0063
  • 3,373 View
  • 130 Download
  • 2 Citations
Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
We investigated the impact of the coronavirus disease 2019 (COVID-19) pandemic on tuberculosis (TB) management in the Republic of Korea (ROK).
Methods
This retrospective cross-sectional study used nationwide ROK TB notification data (98,346 cases) from 2017 to 2020. The median time from the onset of TB symptoms to treatment initiation and the compliance rates with the required timing for notification and individual case investigations were measured and compared across periods and regions affected by the COVID-19 epidemic.
Results
TB diagnosis during the COVID-19 pandemic was delayed. The median time to TB treatment initiation (25 days) in 2020 increased by 3 days compared to that of the previous 3 years (22 days) (p<0.0001). In the outbreak in Seoul, Incheon, and Gyeonggi province during August, the time to TB diagnosis was 4 days longer than in the previous 3 years (p=0.0303). In the outbreak in Daegu and Gyeongbuk province from February to March 2020, the compliance rate with the required timing for individual case investigations was 2.2%p points lower than in other areas in 2020 (p=0.0148). For public health centers, the rate was 13%p lower than in other areas (80.3% vs. 93.3%, p=0.0003).
Conclusion
TB diagnoses during the COVID-19 pandemic in the ROK were delayed nationwide, especially for patients notified by public-private mix TB control hospitals. TB individual case investigations were delayed in regional COVID-19 outbreak areas (Daegu and Gyeongbuk province), especially in public health centers. Developing strategies to address this issue will be helpful for sustainable TB management during future outbreaks.
Trends in recent waterborne and foodborne disease outbreaks in South Korea, 2015–2019
Sang Hyuk Lee, Jae-Won Yun, Ji Hee Lee, Yeon Haw Jung, Dong Han Lee
Osong Public Health Res Perspect. 2021;12(2):73-79.   Published online April 29, 2021
DOI: https://doi.org/10.24171/j.phrp.2021.12.2.04
  • 2,899 View
  • 112 Download
  • 3 Citations
AbstractAbstract PDF
Objectives
This study analyzed trends in foodborne and waterborne diseases in South Korea between 2015 and 2019.
Methods
The data consisted of information on outbreaks of waterborne and foodborne infectious diseases reported through the Korea Centers for Disease Control and Prevention (KCDC) system. We analyzed the trends and epidemiological aspects of outbreaks by month, place of occurrence, and causative pathogens in this observational study.
Results
The number of outbreaks has steadily increased over the last 5 years, but the number of cases per outbreak has followed a decreasing trend. Incidence at daycare centers and preschools has been steadily increasing over consecutive years.
Conclusion
The steady number of patients and decreasing number of cases per outbreak, even as the number of outbreaks has been increasing, suggest that the KCDC’s professional management system is operating effectively. It is necessary to continue improving the objectivity and efficiency of the management system and to carefully examine the increasing number of outbreaks in smaller-scale group catering facilities, such as daycare centers and preschools. Outbreaks can be prevented by closely examining those caused by unidentified pathogens and group outbreaks caused by other diseases, identifying problems, and supplementing the management system.
Alarm Thresholds for Pertussis Outbreaks in Iran: National Data Analysis
Yousef Alimohamadi, Seyed Mohsen Zahraei, Manoochehr Karami, Mehdi Yaseri, Mojtaba Lotfizad, Kourosh Holakouie-Naieni
Osong Public Health Res Perspect. 2020;11(5):309-318.   Published online October 22, 2020
DOI: https://doi.org/10.24171/j.phrp.2020.11.5.07
  • 2,712 View
  • 39 Download
  • 1 Citations
AbstractAbstract PDF
Objectives

The purpose of the current study was to determine the upper threshold number of cases for which pertussis infection would reach an outbreak level nationally in Iran.

Methods

Data on suspected cases of pertussis from the 25th February 2012 to the 23rd March 2018 from the Center for Disease Control and Prevention in Iran was used. The national upper threshold level was estimated using the exponentially weighted moving average (EWMA) method and the Poisson regression method.

Results

In total, 2,577 (33.6%) and 1,714 (22.3%) cases were reported in the Spring and Summer respectively. There were 1,417 (18.5%) and 1,971 (25.6%) cases reported in the Autumn and Winter, respectively. The overall upper threshold using the EWMA and the Poisson regression methods, was estimated as a daily occurrence of 8 (7.55) and 7.50 (4.48–11.06) suspected cases per 10,000,000 people, respectively. The daily seasonal thresholds estimated by the EWMA and the Poisson regression methods were 10, 7, 6, 8 cases and 10, 7, 7, 9 cases for the Spring, Summer, Autumn, and Winter, respectively.

Conclusion

The overall and seasonal estimated thresholds by the 2 methods were similar. Therefore, the estimated thresholds of 6–10 cases in a day, per 10,000,000 people could be used to detect pertussis outbreaks and epidemics by health policymakers.

2019 Tabletop Exercise for Laboratory Diagnosis and Analyses of Unknown Disease Outbreaks by the Korea Centers for Disease Control and Prevention
Il-Hwan Kim, Jun Hyeong Jang, Su-Kyoung Jo, Jin Sun No, Seung-Hee Seo, Jun-Young Kim, Sang-Oun Jung, Jeong-Min Kim, Sang-Eun Lee, Hye-Kyung Park, Eun-Jin Kim, Jun Ho Jeon, Myung-Min Choi, Boyeong Ryu, Yoon Suk Jang, Hwami Kim, Jin Lee, Seung-Hwan Shin, Hee Kyoung Kim, Eun-Kyoung Kim, Ye Eun Park, Cheon-Kwon Yoo, Sang-Won Lee, Myung-Guk Han, Gi-Eun Rhie, Byung Hak Kang
Osong Public Health Res Perspect. 2020;11(5):280-285.   Published online October 22, 2020
DOI: https://doi.org/10.24171/j.phrp.2020.11.5.03
  • 3,034 View
  • 83 Download
AbstractAbstract PDF
Objectives

The Korea Centers for Disease Control and Prevention has published “A Guideline for Unknown Disease Outbreaks (UDO).” The aim of this report was to introduce tabletop exercises (TTX) to prepare for UDO in the future.

Methods

The UDO Laboratory Analyses Task Force in Korea Centers for Disease Control and Prevention in April 2018, assigned unknown diseases into 5 syndromes, designed an algorithm for diagnosis, and made a panel list for diagnosis by exclusion. Using the guidelines and laboratory analyses for UDO, TTX were introduced.

Results

Since September 9th, 2018, the UDO Laboratory Analyses Task Force has been preparing TTX based on a scenario of an outbreak caused by a novel coronavirus. In December 2019, through TTX, individual missions, epidemiological investigations, sample treatments, diagnosis by exclusions, and next generation sequencing analysis were discussed, and a novel coronavirus was identified as the causal pathogen.

Conclusion

Guideline and laboratory analyses for UDO successfully applied in TTX. Conclusions drawn from TTX could be applied effectively in the analyses for the initial response to COVID-19, an ongoing epidemic of 2019 – 2020. Therefore, TTX should continuously be conducted for the response and preparation against UDO.

Brief Reports
Enhancing ‘Whole-of-Government’ Response to Biological Events in Korea: Able Response 2014
Sangwoo Tak, Anton Jareb, Suon Choi, Marvin Sikes, Yeon Hwa Choi, Hyeong-wook Boo
Osong Public Health Res Perspect. 2018;9(1):32-35.   Published online December 31, 2017
DOI: https://doi.org/10.24171/j.phrp.2018.9.1.06
  • 2,851 View
  • 34 Download
  • 1 Citations
AbstractAbstract PDF

Since 2011, the Republic of Korea (ROK) and United States (U.S.) have been collaborating to conduct inter- and intra-governmental exercises to jointly respond to biological events in Korea. These exercises highlight U.S. interest in increasing its global biosurveillance capability and the ROK’s interest in improving cooperation among ministries to respond to crises. With Able Response (AR) exercises, the ROK and U.S. have improved coordination among US and ROK government and defense agencies responding to potential bio-threats and identified additional areas on which to apply refinements in policies and practices. In 2014, the AR exercise employed a Biosurveillance Portal (BSP) to facilitate more effective communication among participating agencies and countries including Australia. In the present paper, we seek to provide a comprehensive assessment of the AR 2014 (AR14) exercise and make recommendations for future improvements. Incorporating a more realistic response in future scenarios by integrating a tactical response episode in the exercise is recommended.

Emergence of Norovirus GII.17-associated Outbreak and Sporadic Cases in Korea from 2014 to 2015
Sunyoung Jung, Bo-Mi Hwang, HyunJu Jung, GyungTae Chung, Cheon-Kwon Yoo, Deog-Yong Lee
Osong Public Health Res Perspect. 2017;8(1):86-90.   Published online February 28, 2017
DOI: https://doi.org/10.24171/j.phrp.2017.8.1.12
  • 2,156 View
  • 22 Download
  • 7 Citations
AbstractAbstract PDF

Human norovirus are major causative agent of nonbacterial acute gastroenteritis. In general, genogroup (G) II.4 is the most prominent major genotype that circulate in human population and the environment. However, a shift in genotypic trends was observed in Korea in December 2014. In this study, we investigated the trend of norovirus genotype in detail using the database of Acute Diarrhea Laboratory Surveillance (K-EnterNet) in Korea. GII.17 has since become a major contributor to outbreaks of norovirus-related infections and sporadic cases in Korea, although the reason for this shift remain unknown.

Occurrence of Norovirus GII.4 Sydney Variant-related Outbreaks in Korea
Sunyoung Jung, Bo-Mi Hwang, Hyun Ju Jeong, Gyung Tae Chung, Cheon-Kwon Yoo, Yeon-Ho Kang, Deog-Yong Lee
Osong Public Health Res Perspect. 2015;6(5):322-326.   Published online October 31, 2015
DOI: https://doi.org/10.1016/j.phrp.2015.10.004
  • 1,399 View
  • 17 Download
  • 7 Citations
AbstractAbstract PDF
Human noroviruses are major causative agents of food and waterborne outbreaks of nonbacterial acute gastroenteritis. In this study, we report the epidemiological features of three outbreak cases of norovirus in Korea, and we describe the clinical symptoms and distribution of the causative genotypes. The incidence rates of the three outbreaks were 16.24% (326/2,007), 4.1% (27/656), and 16.8% (36/214), respectively. The patients in these three outbreaks were affected by acute gastroenteritis. These schools were provided unheated food from the same manufacturing company. Two genotypes (GII.3 and GII.4) of the norovirus were detected in these cases. Among them, major causative strains of GII.4 (Hu-jeju-47-2007KR-like) were identified in patients, food handlers, and groundwater from the manufacturing company of the unheated food. In the GII.4 (Hu-jeju-47-2007KR-like) strain of the norovirus, the nucleotide sequences were identical and identified as the GII.4 Sydney variant. Our data suggests that the combined epidemiological and laboratory results were closely related, and the causative pathogen was the GII.4 Sydney variant strain from contaminated groundwater.
Ebola Hemorrhagic Fever and the Current State of Vaccine Development
Joo Eun Hong, Kee-Jong Hong, Woo Young Choi, Won-Ja Lee, Yeon Hwa Choi, Chung-Hyeon Jeong, Kwang-il Cho
Osong Public Health Res Perspect. 2014;5(6):378-382.   Published online December 31, 2014
DOI: https://doi.org/10.1016/j.phrp.2014.09.006
  • 1,572 View
  • 15 Download
  • 5 Citations
AbstractAbstract PDF
Current Ebola virus outbreak in West Africa already reached the total number of 1,323 including 729 deaths by July 31st. the fatality is around 55% in the southeastern area of Guinea, Sierra Leone, Liberia, and Nigeria. The number of patients with Ebola Hemorrhagic Fever (EHF) was continuously increasing even though the any effective therapeutics or vaccines has not been developed yet. The Ebola virus in Guinea showed 98% homology with Zaire Ebola Virus.Study of the pathogenesis of Ebola virus infection and assess of the various candidates of vaccine have been tried for a long time, especially in United States and some European countries. Even though the attenuated live vaccine and DNA vaccine containing Ebola viral genes were tested and showed efficacy in chimpanzees, those candidates still need clinical tests requiring much longer time than the preclinical development to be approved for the practical treatment.It can be expected to eradicate Ebola virus by a safe and efficient vaccine development similar to the case of smallpox virus which was extinguished from the world by the variola vaccine.
Original Articles
Emerging Pathogens and Vehicles of Food- and Water-borne Disease Outbreaks in Korea, 2007–2012
Shinje Moon, Il-Woong Sohn, Yeongseon Hong, Hyungmin Lee, Ji-Hyuk Park, Geun-Yong Kwon, Sangwon Lee, Seung-Ki Youn
Osong Public Health Res Perspect. 2014;5(1):34-39.   Published online February 28, 2014
DOI: https://doi.org/10.1016/j.phrp.2013.12.004
  • 1,444 View
  • 16 Download
  • 13 Citations
AbstractAbstract PDF
Objectives
Food- and water-borne disease outbreaks (FBDOs) are an important public health problem worldwide. This study investigated the trends in FBDOs in Korea and established emerging causal pathogens and causal vehicles.
Methods
We analyzed FBDOs in Korea by year, location, causal pathogens, and causal vehicles from 2007 to 2012. Information was collected from the FBDOs database in the Korean Centers for Disease Control and Prevention.
Results
During 2007–2012, a total of 1794 FBDOs and 48,897 patients were reported. After 2007, FBDOs and patient numbers steadily decreased over the next 2 years and then plateaued until 2011. However, in 2012, FBDOs increased slightly accompanied by a large increase in the number of affected patients. Our results highlight the emergence of norovirus and pathogenic Escherichia coli other than enterohemorrhagic E. coli (EHEC) in schools in 2012. We found that pickled vegetables is an emerging causal vehicle responsible for this problem.
Conclusion
On the basis of this study we recommend intensified inspections of pickled vegetable manufacturers and the strengthening of laboratory surveillance of relevant pathogens.
The First Outbreak of Giardiasis with Drinking Water in Korea
Hyeng-Il Cheun, Cheon-Hyeon Kim, Shin-Hyeong Cho, Da-Won Ma, Bo-La Goo, Mun-Su Na, Seung-Ki Youn, Won-Ja Lee
Osong Public Health Res Perspect. 2013;4(2):89-92.   Published online April 30, 2013
DOI: https://doi.org/10.1016/j.phrp.2013.03.003
  • 1,504 View
  • 17 Download
  • 19 Citations
AbstractAbstract PDF
Objectives
To identify the pathogen of the diarrhea outbreak in a village in Jeollabuk province in Korea in April 2010.
Methods
DNA extraction was performed from the 120 L of collected water, which was centrifuged at 10,000 x g for 30 min. PCR reactions were conducted in a total of 25 ul, which included PCR premix (GenDEPOT, Barker, TX, USA), 2 ul (∼100 ng) of extracted DNA, and 10 pmol of each primer.
Results
Nine people out of 25 had a symptom of abdominal pain accompanied by diarrhea after they used stored valley water in a water tank as a provisional water supply source without chlorine sterilization. Among them Giardia lamblia was detected in fecal samples of 7 people using the polymerase chain reaction method. Although G. lamblia was also detected from water provided by the provisional water supply system stored in the water tank and used as drinking water, it was not detected in the water tank itself. This water-borne outbreak is considered to have occurred when the provisional water supply tube was destroyed under a building construction and contaminated by G. lamblia, but its precise cause has not been clarified.
Conclusion
This outbreak resulting from G. lamblia is very meaningful as the first outbreak of an infection by a water-borne parasite in Korea.
Articleses
Early Detection of Nosocomial Outbreaks Caused by Rare Pathogens: A Case Study Employing Score Prediction Interval
Hiroshi Nishiura
Osong Public Health Res Perspect. 2012;3(3):121-127.   Published online June 30, 2012
DOI: https://doi.org/10.1016/j.phrp.2012.07.010
  • 1,324 View
  • 14 Download
  • 8 Citations
AbstractAbstract PDF
Objectives
Nosocomial outbreaks involve only a small number of cases and limited baseline data. The present study proposes a method to detect the nosocomial outbreaks caused by rare pathogens, exploiting score prediction interval of a Poisson distribution.
Methods
The proposed method was applied to three empirical datasets of nosocomial outbreaks in Japan: outbreaks of (1) multidrug-resistant Acinetobacter baumannii (n = 46) from 2009 to 2010, (2) multidrug-resistant Pseudomonas aerginosa (n = 18) from 2009 to 2010, and (3) Serratia marcescens (n = 226) from 1999 to 2000.
Results
The proposed method successfully detected all three outbreaks during the first 2 months. Both the model-based and empirically derived threshold values indicated that the nosocomial outbreak of rare infectious disease may be declared upon diagnosis of index case(s), although the sensitivity and specificity were highly variable.
Conclusion
The findings support the practical notion that, upon diagnosis of index patient(s), one should immediately start the outbreak investigation of nosocomial outbreak caused by a rare pathogen. The proposed score prediction interval can permit easy computation of outbreak threshold in hospital settings among healthcare experts.
Enteropathogenic Escherichia coli Outbreak and its Incubation Period: Is it Short or Long?
Dong-Woo Lee, Jin Gwack, Seun-Ki Youn
Osong Public Health Res Perspect. 2012;3(1):43-47.   Published online December 31, 2011
DOI: https://doi.org/10.1016/j.phrp.2012.01.007
  • 1,222 View
  • 19 Download
  • 5 Citations
AbstractAbstract PDF
Objectives
The aim of this study is to determine the incubation period of enteropathogenic Escherichia coli (EPEC), which creates several outbreaks in a year in South Korea.
Methods
We reviewed all water and food-borne outbreaks data reported to the Korea Centers for Disease Control and Prevention (KCDC) from 2009 to 2010 and determined their characteristics. Through this process, we can presume the incubation period of EPEC among outbreaks in South Korea.
Results
A total of 497 water and food-borne outbreaks were reported to KCDC and 66 (13.28%) are defined as E coli-origin outbreaks. EPEC was the most common subtype of E coli, being confirmed as a causative organism in 26 outbreaks. Overall attack rate was 15.85% (range 0.9–100). The subjects were eight outbreaks that have a clear history of single exposure and we can estimate the incubation time of EPEC as minimum 0.5 hours to maximum 34.0 hours with a mean 12.9 hours (range 4.5–24.0). The cases of those cannot completely rule out the chance of multiple exposure from same source or place have minimum 1.0 hour, to a maximum of 195.5 hours and a mean 30.5 (range 22.7–61.0) hours of incubation period.
Conclusions
This serial analysis suggests that EPEC has actually shorter mean incubation period as much as 12 hours. When this period is longer than 1 day or over, then the epidemiologic investigator should consider the chance of repeated or continuous exposure by making it clear whether there is any chance of any other exposure in common.

PHRP : Osong Public Health and Research Perspectives