Publications by authors named "NamJoo Lee"

As COVID-19 has become endemic, SARS-CoV-2 variants are becoming increasingly diverse, underscoring the escalating importance of global genomic surveillance. This study analyzed 86,762 COVID-19 samples identified in the Republic of Korea from September 2022 to November 2023. The results revealed a consistent increase in the prevalence of the XBB variants following the dominance of BN.

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The prevalence of highly pathogenic avian influenza (HPAI) A(H5N1) viruses has increased in wild birds and poultry worldwide, and concomitant outbreaks in mammals have occurred. During 2023, outbreaks of HPAI H5N1 virus infections were reported in cats in South Korea. The H5N1 clade 2.

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The adenovirus detection rate is <10% throughout the year in South Korea; however, during the summer of 2023, it showed an unusual increase. We analyzed the adenovirus detection rate using data from the Korea Respiratory Integrated Surveillance System before and after coronavirus disease (COVID-19) collected from 2019 to week 36 of 2023. Before the COVID-19 outbreak in 2019, the mean detection rate was 8.

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Article Synopsis
  • The COVID-19 pandemic led to a significant decline in the incidence of various respiratory viruses due to health measures, but these infections returned as restrictions were lifted, particularly in Korean children.
  • A nationwide surveillance study analyzed respiratory virus data from children and adolescents from January 2017 to June 2023, comparing detection rates and age distributions before and after the pandemic.
  • Findings showed a drop in overall virus detection during the pandemic, with a notable increase in co-detections post-pandemic; unique outbreaks of certain viruses like PIV and HMPV occurred out of season, and the average age of affected children increased significantly in 2023 compared to pre-pandemic years.
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  • The Korea Disease Control and Prevention Agency (KDCA) is conducting genomic surveillance to track and analyze SARS-CoV-2 variants in South Korea using over 102,000 patient samples.
  • COVID-19 variant waves emerged first internationally and then spread domestically, with key variants including B.41 in 2020, Delta in 2021, and various Omicron sub-lineages in 2022.
  • The KDCA has been proactive in detecting new variants before widespread outbreaks, highlighting the need for ongoing monitoring to safeguard public health against emerging threats.
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Background: Coronavirus disease 2019 (COVID-19) has been declared a global pandemic owing to the rapid spread of the causative agent, severe acute respiratory syndrome coronavirus 2. Its Delta and Omicron variants are more transmissible and pathogenic than other variants. Some debates have emerged on the mechanism of variants of concern.

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Article Synopsis
  • - Since the COVID-19 pandemic began, there has been a significant decline in the detection of respiratory infectious diseases, particularly influenza, due to decreased specimen collection as most patients are directed to COVID-19 screening clinics.
  • - To address this issue, the Korea Disease Control and Prevention Agency expanded surveillance efforts by including data from private medical diagnostic centers, leading to an unexpected rise in human parainfluenza virus (hPIV) detections beginning in August 2021.
  • - The increase in hPIV detections was especially notable in young children, with rates surpassing 70% by October 2021, and the detection occurred later in metropolitan areas compared to suburban areas, indicating a shift in prevalence patterns during the
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We analyzed the duration of infectivity of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant by viral culture of respiratory samples collected daily from isolated patients with SARS-CoV-2 infection. The culture positivity rate of the Omicron variant was higher than that of the Delta variant within 8 days after symptom onset.

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly, causing in COVID-19 being declared a global pandemic by the World Health Organization. The key variants include alpha, beta, gamma, and delta; these exhibit high viral transmission, pathogenicity, and immune evasion mechanisms. The delta variant, first confirmed in India, was detected in the majority of COVID-19 patients at the recent wave in the Republic of Korea.

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We report the rapid emergence of severe acute respiratory syndrome coronavirus 2 lineages B.1.619 and B.

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Article Synopsis
  • As COVID-19 continues, reinfections are likely to rise, but confirmation is challenging due to the need for whole-genome sequencing to assess genetic differences between infections.* -
  • In a study of four suspected reinfection cases in young patients (ages 10-29), researchers found that only two were confirmed reinfections, both involving the Epsilon variant.* -
  • The study highlights the increasing potential for reinfections amid the ongoing pandemic and emphasizes the importance of continuous monitoring of COVID-19 cases.*
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  • The study investigates how genomic epidemiology was used to analyze the spread of SARS-CoV-2 in South Korea by examining viral genome sequences from over 2,000 cases during 2020.
  • The analysis found that while most imported cases from travelers did not spread widely, four viral subgroups caused local outbreaks, which were eventually controlled after enhanced social distancing measures were implemented.
  • The results suggest that South Korea's traveler quarantine and social distancing strategies were effective in reducing virus spread, but further improvements are needed to fully control variants and future pandemics.
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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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Background: After the detection of the first case of coronavirus disease 2019 (COVID-19) in South Korea on January 20, 2019, it has triggered three major outbreaks. To decrease the disease burden of COVID-19, social distancing and active mask wearing were encouraged, reducing the number of patients with influenza-like illness and altering the detection rate of influenza and respiratory viruses in the Korea Influenza and Respiratory Viruses Surveillance System (KINRESS). We examined the changes in respiratory viruses due to COVID-19 in South Korea and virological causes of the high detection rate of human rhinovirus (hRV) in 2020.

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Article Synopsis
  • 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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Article Synopsis
  • - A novel beta-coronavirus, SARS-CoV-2, emerged in December 2019, leading to a global outbreak and prompting genomic surveillance in South Korea.
  • - The Korea Disease Control and Prevention Agency sequenced 2,488 SARS-CoV-2 samples over a year, noting a shift in dominant virus clades from S and V to GH by March 2020.
  • - The study found that quarantining international travelers effectively limited the spread of multiple SARS-CoV-2 variants within Korea.
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Background: The emergence of influenza viruses resistant to anti-influenza drugs is a threat to global public health. The Korea Centers for Disease Control and Prevention operates the Korea Influenza and Respiratory Viruses Surveillance System (KINRESS) to monitor epidemics of influenza and Severe Acute Respiratory Infection (SARI) to identify mutated influenza viruses affecting drug resistance, pathogenesis, and transmission.

Methods: Oropharyngeal swab samples were collected from KINRESS and SARI during the 2018-2019 season.

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  • The study investigates the potential transmission of SARS-CoV-2, the virus causing COVID-19, through non-respiratory routes such as serum, urine, and stool in hospitalized patients.
  • Out of 74 patients, SARS-CoV-2 was detected in 15 samples, with the highest detection rate in stool (10.1%).
  • The findings suggest that although the virus can be detected in non-respiratory samples, it could not be isolated, indicating a low risk of transmission through these routes.
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Objectives: Following reports of patients with unexplained pneumonia at the end of December 2019 in Wuhan, China, the causative agent was identified as coronavirus (SARS-CoV-2), and the 2019 novel coronavirus disease was named COVID-19 by the World Health Organization. Putative patients with COVID-19 have been identified in South Korea, and attempts have been made to isolate the pathogen from these patients.

Methods: Upper and lower respiratory tract secretion samples from putative patients with COVID-19 were inoculated onto cells to isolate the virus.

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We evaluated genetic variation in Middle East respiratory syndrome coronavirus (MERS-CoV) imported to South Korea in 2018 using specimens from a patient and isolates from infected Caco-2 cells. The MERS-CoV strain in this study was genetically similar to a strain isolated in Riyadh, Saudi Arabia, in 2017.

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The prevalence of eight respiratory viruses detected in patients with acute respiratory infections (ARIs) in Korea was investigated through analysis of data recorded by the Korea Influenza and Respiratory Viruses Surveillance System (KINRESS) from 2013 to 2015. Nasal aspirate and throat swabs specimens were collected from 36 915 patients with ARIs, and viral nucleic acids were detected by real-time (reverse-transcription) polymerase chain reaction for eight respiratory viruses, including human respiratory syncytial viruses (HRSVs), influenza viruses (IFVs), human parainfluenza viruses (HPIVs), human coronaviruses (HCoVs), human rhinovirus (HRV), human adenovirus (HAdV), human bocavirus (HBoV), and human metapneumovirus (HMPV). The overall positive rate of patient specimens was 49.

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Outbreaks of avian influenza virus H5N8 first occurred in 2014, and spread to poultry farms in Korea. Although there was no report of human infection by this subtype, it has the potential to threaten human public health. Therefore, we evaluated the pathogenesis of H5N8 viruses in ferrets.

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Since the pandemic influenza A (H1N1) 2009 ((H1N1)pdm09) virus spread all over the world, the (H1N1)pdm09 virus has been circulating with seasonal influenza viruses. We developed rapid and sensitive one-step multiplex real-time RT-PCR assays (rRT-PCR) for simultaneous detection of influenza viruses currently circulating in humans, and the avian A/H5 virus. The detection limit of each assay was 4.

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