Publications by authors named "Yoon-Seok Chung"

: Despite its global eradication in 1977, smallpox remains a concern owing to its potential as a biological agent, thereby prompting the ongoing development and utilization of its vaccine. Vaccination with the virus induces immunity against variola virus, the causative agent of smallpox; however, this immunity does not extend to viruses of different genera within the family. In this study, we aimed to assess the efficacy of an enzyme-linked immunosorbent assay (ELISA) method utilizing virus and recombinant A27L antigen for detecting antibodies against smallpox.

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  • - The study analyzes SARS-CoV-2 genetic data from COVID-19 patients in Gwangju, South Korea, from 2020 to 2022 to understand variance trends and infection patterns over time.
  • - Key variants identified included B.41, B.1.497, B.1.619.1, and B.1.617.2, with a notable increase in the rapid spread of the Omicron variant after its identification in late December 2021.
  • - Findings highlight the importance of regional genomic surveillance alongside national efforts to enhance variant tracking and improve overall infectious disease management.
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  • - The study investigated how long measles vaccine virus (MeVV) RNA and measles-specific antibodies can be detected in children after receiving the MMR vaccine during a measles outbreak in South Korea.
  • - Out of 206 vaccinated children, two tested positive for MeVV RNA, with one child showing RNA 448 days post-vaccination and another exhibiting measles-specific antibodies 1097 days later.
  • - The findings suggest that MeVV RNA and specific antibodies can persist for an extended period, indicating that doctors should carefully interpret positive test results in vaccinated children showing measles symptoms.
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  • - The study focused on analyzing the genomes of monkeypox virus isolates from patients in the Republic of Korea to understand how the virus spreads and evolves over time.
  • - Eight monkeypox virus isolates were classified into Clade IIb, with notable lineages identified including B.1.1, A.2.1, and B.1.3, with B.1.3 being prevalent among isolates from 2023.
  • - The findings suggest that the unique genetic characteristics of these Far East isolates indicate a possible start of local transmission of the B.1.3 lineage in early 2023, particularly among six patients with no recent travel history.
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Coxsackievirus A6 (CV-A6) has emerged as the predominant causative agent of hand, foot, and mouth disease (HFMD) in young children. Since the declaration of coronavirus disease 2019 (COVID-19) as a global pandemic, the incidence of infectious diseases, including HFMD, has decreased markedly. When social mitigation was relaxed during the COVID-19 pandemic in 2022, the re-emergence of HFMD was observed in Gwangju, South Korea, and seasonal characteristics of the disease appeared to have changed.

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Following the worldwide surge in mpox (monkeypox) in 2022, cases have persisted in Asia, including South Korea, and sexual contact is presumed as the predominant mode of transmission, with a discernible surge in prevalence among immunocompromised patients. Drugs such as tecovirimat can result in drug-resistant mutations, presenting obstacles to treatment. This study aimed to ascertain the presence of tecovirimat-related resistant mutations through genomic analysis of the monkeypox virus isolated from a reported case involving prolonged viral shedding in South Korea.

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Ticks are important vectors of the tick-borne encephalitis virus (TBEV). In Kyrgyzstan, the livestock farming trade and nomadic lifestyle enable tick-borne diseases to be imported from neighboring countries, but there are few relevant studies. In this study, we collected 40 ticks from cattle in Kyrgyzstan.

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The non-pharmaceutical interventions implemented to prevent the spread of COVID-19 have affected the epidemiology of other respiratory viruses. In South Korea, Human metapneumovirus (HMPV) typically occurs from winter to the following spring; however, it was not detected for two years during the COVID-19 pandemic and re-emerged in the fall of 2022, which is a non-epidemic season. To examine the molecular genetic characteristics of HMPV before and after the COVID-19 pandemic, we analyzed 427 HMPV-positive samples collected in the Gwangju area from 2018 to 2022.

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Background: Despite the high vaccination coverage rate, in-hospital transmission of measles continues to occur in South Korea. We present a measles outbreak in which two healthcare workers (HCWs) with presumptive evidence of measles immunity were infected by a patient with typical measles at a single hospital in South Korea. This facilitated the evaluation of measles seroprevalence in all HCWs.

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  • The study investigates SARS-CoV-2 variants on Jeju Island, South Korea, from February 2021 to September 2022, utilizing genomic surveillance to track changes.
  • The dominant Alpha variant was replaced by Delta in July 2021, with Omicron becoming prevalent by December 2021, showcasing the rapid evolution of the virus.
  • Findings highlight key spike protein mutations (N440K and G446S) linked to immune evasion, emphasizing the importance of monitoring variants to manage the pandemic effectively.*
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  • A study conducted in 2021 in the Honam region of South Korea assessed the effectiveness of COVID-19 vaccines and monitored changes in dominant virus strains.
  • Results showed a high vaccination rate of 88.6%, with overall vaccine effectiveness at 98.7% and a breakthrough infection rate of just 0.16%.
  • The emergence of new variants like Delta and Omicron impacted vaccine effectiveness over time, but receiving booster doses helped restore antibody levels, ensuring continued protection.
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Mumps is the second-most reported infectious disease in South Korea; however, due to the low pathogen confirmation rate in laboratory diagnoses, we proposed a method for reevaluating the high incidence rate via the laboratory verification of other viral diseases. In 2021, 63 cases of pharyngeal or cheek mucosal swabs of suspected mumps cases in Gwangju, South Korea, were assessed for causative pathogens using massive simultaneous pathogen testing. More than one respiratory virus was detected in 60 cases (95.

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To investigate viruses in measles-negative cases, 221 measles-suspected samples collected in Gyeonggi Province, South Korea were tested using a real-time PCR assay. Rubella virus was not detected. However, 11 cases of parvovirus B19 (5.

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Background: Determination of the release from isolation for coronavirus disease 2019 (COVID-19) in immunocompromised patients who need additional hospitalization for treatment of non-COVID-19 related disease is important to prevent nosocomial transmission. However, there is insufficient evidence for an extended isolation period.

Materials And Methods: In September 2021, when the Delta variant was dominant, a nosocomial outbreak of COVID-19 occurred in the nephrology ward of a tertiary hospital in Gwangju, Korea.

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  • Community mitigation measures during the COVID-19 pandemic led to a decrease and delayed occurrence of respiratory viruses, including human parainfluenza virus type 3 (HPIV3) in Gwangju, Korea, with a peak outbreak observed in September-October 2021.
  • Genetic analyses of 129 HPIV3 strains from 2018 to 2021 revealed reduced diversity in 2021 compared to previous years, likely due to limited virus inflow from other regions as a result of mitigation efforts.
  • The 2021 HPIV3 strains showed significant genetic similarities to older sequences from Japan and India, highlighting the potential risk of a new lineage disrupting community immunity and emphasizing the need for ongoing viral monitoring.
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Most HIV-positive individuals diagnosed in Korea are infected through sexual contact, with the time of HIV infection therefore often being unknown. The aim of this study was to investigate the characteristics of diagnosed patients near the time of HIV seroconversion to establish useful HIV intervention strategies. Cross-sectional study.

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The number of coronavirus disease (COVID-19)-positive cases has increased in Jeju Island, Republic of Korea. Identification and monitoring of new mutations in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are extremely important to fighting the global pandemic. We report a breakout of the B.

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Three genotypes (B3, D8, and H1) of the measles virus (MeV) have recently caused global outbreaks. In Korea, four measles outbreaks were reported during 2018-2019 and most patients were infants and health care workers in their 20s and 30s. To investigate the genetic characteristics and molecular epidemiology of the outbreaks, we analyzed the sequence of MeVs by targeting the N-450, MF-NCR, and/or H gene regions.

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  • The study focused on individuals who re-tested positive for SARS-CoV-2 after recovering from their initial infection to assess the virus's infectivity.
  • Researchers analyzed 295 people with re-positive PCR results and their 836 close contacts, finding no viral presence in cell cultures from those with re-positive tests.
  • Out of the close contacts, three new cases of infection were identified, but all had prior infections, indicating that there was no evidence of targeted transmission from those with re-positive test results.
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  • A new real-time reverse transcription polymerase chain reaction (RT-qPCR) test for detecting SARS-CoV-2 was developed and validated, not requiring Emergency Use Authorization (EUA) reagents.
  • This assay demonstrated high specificity for SARS-CoV-2, as it did not amplify other respiratory viruses, and maintained excellent performance metrics such as sensitivity and accuracy.
  • With a low limit of detection and strong repeatability, this RT-qPCR assay can effectively support early COVID-19 diagnosis in South Korea without relying on existing EUA-approved kits.
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We report the response process of the Laboratory Analysis Task Force (LATF) for Unknown Disease Outbreaks (UDOs) at the Korea Disease Control and Prevention Agency (KDCA) during January 2020 to coronavirus disease 2019 (COVID-19), which developed as a UDO in Korea. The advanced preparedness offered by the laboratory diagnostic algorithm for UDOs related to respiratory syndromes was critical for the rapid identification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and enabled us to establish and expand the diagnostic capacity for COVID-19 on a national scale in a timely manner.

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The 17 Provincial Institutes of Health and Environment (PIHEs) in Korea use HIV antibody, antigen, and Western blot assays for confirmatory testing of HIV infection. The Korea Disease Control and Prevention Agency (KDCA) has further included p24 antigen neutralization and nucleic acid tests (NATs) since 2015. Our study aimed to investigate the effect of this new testing algorithm on the confirmation rate of HIV infection.

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The South Korean government effectively contained the coronavirus disease-2019 (COVID-19) outbreak primarily associated with a religious group. We conducted SARS-CoV-2 whole genome sequencing of 66 cases to investigate connections among the initial South Korean cases and the religious group outbreak. We assessed the accuracy of genomic investigation by comparing the whole genome sequences with comprehensive contact tracing records.

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Objectives: An epidemiological investigation was conducted into a hepatitis C virus (HCV) outbreak at an outpatients clinic in Seoul (2011-2012). The aim of the study was to analyze the scale of infection, identify the source of infection, and route of transmission to prevent hepatitis C transmission in the future.

Methods: A retrospective study of the outpatients and health care workers ( = 7,285) in the target outpatient clinic during 2011-2012 was conducted.

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