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Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally, leading to the coronavirus disease 2019 (COVID-19) pandemic. Because a significant proportion of the COVID-19 confirmed cases were concentrated in the capital metropolitan area of South Korea, and a large proportion of the population in the area had been adequately vaccinated against COVID-19, we conducted a seroprevalence surveillance study focusing on the residents of the capital metropolitan area in South Korea., Methods: We used a quota-sampling method to obtain blood samples from 1,000 individuals per round, equally stratified across seven age categories and sexes and regions, from five medical institutions located within the capital metropolitan area of South Korea. During five consecutive months (rounds) between January 2022 and May 2022, a total of 5,000 samples were analyzed for anti-spike (S) and anti-nucleocapsid (N) antibodies., Results: High anti-S seropositivity was observed in all age groups, which corresponded to the vaccine coverage during the study period. Both the cumulative incidence based on polymerase chain reaction (PCR) and the estimated seroprevalence based on anti-N seropositivity increased in the fourth and fifth rounds, which corresponded to April 2022 and May 2022. Seroprevalence coincided with the cumulative incidence during the first three rounds, but exceeded from the fourth survey onwards when infection with omicron variants was increased rapidly in Korea., Conclusion: Seroprevalence confirmed the number of infection cases outside of PCR testing-based surveillance. Seroepidemiological surveillance can help us understand vaccine responses and detect hidden infections, thereby providing appropriate public health guidance for achieving population-level immunity., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2024 The Korean Academy of Medical Sciences.)

Background: Paradoxical responses (PR) occur more frequently in lymph node tuberculosis (LNTB) than in pulmonary tuberculosis and present difficulties in differential diagnosis of drug resistance, new infection, poor patient compliance, and adverse drug reactions. Although diagnosis of mediastinal LNTB has become much easier with the development of endosonography, limited information is available. The aim of this study was to investigate the clinical course of mediastinal LNTB and the risk factors associated with PR., Methods: Patients diagnosed with mediastinal LNTB via endosonography were evaluated retrospectively between October 2009 and December 2019. Multivariable logistic regression was applied to evaluate the risk factors associated with PR., Results: Of 9,052 patients who underwent endosonography during the study period, 158 were diagnosed with mediastinal LNTB. Of these, 55 (35%) and 41 (26%) concurrently had pulmonary tuberculosis and extrapulmonary tuberculosis other than mediastinal LNTB, respectively. Of 125 patients who completed anti-tuberculosis treatment, 21 (17%) developed PR at a median of 4.4 months after initiation of anti-tuberculosis treatment. The median duration of anti-tuberculosis treatment was 6.3 and 10.4 months in patients without and with PR, respectively. Development of PR was independently associated with age < 55 years (adjusted odds ratio [aOR], 5.72; 95% confidence interval [CI], 1.81-18.14; P = 0.003), lymphocyte count < 800/μL (aOR, 8.59; 95% CI, 1.60-46.20; P = 0.012), and short axis diameter of the largest lymph node (LN) ≥ 16 mm (aOR, 5.22; 95% CI, 1.70-16.00; P = 0.004) at the time of diagnosis of mediastinal LNTB., Conclusion: As PR occurred in one of six patients with mediastinal LNTB during anti-tuberculosis treatment, physicians should pay attention to patients with risk factors (younger age, lymphocytopenia, and larger LN) at the time of diagnosis., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2023 The Korean Academy of Medical Sciences.)

Background: In pediatric patients, the common cold coronavirus (ccCoV) usually causes mild respiratory illness. There are reports of coronavirus causing central nervous system (CNS) infection in experimental animal models. Some immunocompromised patients have also been reported to have fatal CNS infections with ccCoV. The aim of this study was to investigate the clinical characteristics of CNS complications related to ccCoV infection., Methods: From January 2014 to December 2019, a retrospective analysis was performed of medical records from hospitalized patients under 19 years of age whose ccCoV was detected through polymerase chain reaction in respiratory specimens. The CNS complications were defined as clinically diagnosed seizure, meningitis, encephalopathy, and encephalitis., Results: A total of 436 samples from 420 patients were detected as ccCoV. Among the 420 patients, 269 patients were immunocompetent and 151 patients were immunocompromised. The most common type of ccCoV was OC43 (52% in immunocompetent, 37% in immunocompromised). CNS complications were observed in 9.4% (41/436). The most common type of CNS complication was the fever-provoked seizure under pre-existing neurologic disease (42% in immunocompetent and 60% in immunocompromised patients). Among patients with CNS complications, two immunocompetent patients required intensive care unit admission due to encephalitis. Three patients without underlying neurological disease started anti-seizure medications for the first time at this admission. There was no death related to ccCoV infection., Conclusion: ccCoV infection may cause severe clinical manifestations such as CNS complications or neurologic sequelae, even in previously healthy children., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2023 The Korean Academy of Medical Sciences.)

Background: Acinetobacter baumannii infections cause high morbidity and mortality in intensive care unit (ICU) patients. However, there are limited data on the changes of long-term epidemiology of imipenem resistance in A. baumannii bacteremia among pediatric ICU (PICU) patients., Methods: A retrospective review was performed on patients with A. baumannii bacteremia in PICU of a tertiary teaching hospital from 2000 to 2016. Antimicrobial susceptibility tests, multilocus sequence typing (MLST), and polymerase chain reaction for antimicrobial resistance genes were performed for available isolates., Results: A. baumannii bacteremia occurred in 27 patients; imipenem-sensitive A. baumannii (ISAB, n = 10, 37%) and imipenem-resistant A. baumannii (IRAB, n = 17, 63%). There was a clear shift in the antibiogram of A. baumannii during the study period. From 2000 to 2003, all isolates were ISAB (n = 6). From 2005 to 2008, both IRAB (n = 5) and ISAB (n = 4) were isolated. However, from 2009, all isolates were IRAB (n = 12). Ten isolates were available for additional test and confirmed as IRAB. MLST analysis showed that among 10 isolates, sequence type 138 was predominant (n = 7). All 10 isolates were positive for OXA-23-like and OXA-51-like carbapenemase. Of 27 bacteremia patients, 11 were male (41%), the median age at bacteremia onset was 5.2 years (range, 0-18.6 years). In 33% (9/27) of patients, A. baumannii was isolated from tracheal aspirate prior to development of bacteremia (median, 8 days; range, 5-124 days). The overall case-fatality rate was 63% (17/27) within 28 days. There was no statistical difference in the case fatality rate between ISAB and IRAB groups (50% vs. 71%; P = 0.422)., Conclusion: IRAB bacteremia causes serious threat in patients in PICU. Proactive infection control measures and antimicrobial stewardship are crucial for managing IRAB infection in PICU., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2022 The Korean Academy of Medical Sciences.)

Background: This study aimed to investigate the psychosocial symptoms and experiences of bereaved parents of victims and parents of survivors of the Sewol Ferry accident five years after the accident., Methods: In-depth interviews of 186 bereaved parents of victims or survivors of the Sewol Ferry accident were conducted. We elicited and categorized meaning units relevant to the psychological, cognitive, and physical traits of the participants from these interviews. Differences in responses between bereaved parents and survivors' parents and between genders were examined using frequency analyses and χ² tests., Results: Data were organized under seven headings: observed attitude and impression of participants, difficulties due to mental health problems, difficulties due to physical pain, difficulties in relationships, negative changes following the incident, positive changes following the incident, and help needed. Within these headings, 27 themes, 60 sub-themes, and 80 meaning units were elicited., Conclusion: This study explored the psychiatric, physical, and relational problems reported by bereaved parents and those of survivors as well as major changes in their personal and social lives after the Sewol Ferry accident. Differences in responses according to gender were also identified. The results from this study could inform and facilitate the implementation of intervention measures, such as long-term psychological evaluation, to bereaved parents of victims or survivors of disasters., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2022 The Korean Academy of Medical Sciences.)

Background: For the 2018-2019 season, the national influenza immunization program expanded to cover children aged from 6 months to 12 years in Korea. This study aimed to analyze vaccine effectiveness (VE) against influenza in children visiting the pediatric emergency room at a tertiary hospital during the 2018-2019 season., Methods: Patients tested for influenza antigens from October 1st 2018 to May 31st 2019 at the pediatric emergency room of Samsung Medical Center were included. Patients' influenza antigen test results, influenza vaccination history, and underlying medical conditions were reviewed retrospectively. VE was estimated from the test-negative design study., Results: Among the 2,901 visits with influenza test results 1,692 visits of 1,417 patients were included for analysis. Among these 1,417 patients, 285 (20.1%) were positive (influenza A, n = 211, 74.0%; influenza B, n = 74, 26.0%). The VE in all patients was 36.4% (95% confidence interval [CI], 13.9 to 53.1). The VE for influenza A was 37.6% (95% CI, 12.6 to 55.5) and VE for influenza B was 24.0% (?38.5 to 58.3). The VE in the age group 6 months to 12 years was significant with a value of 35.6% (95% CI, 10.5 to 53.7); it was not statistically significant in the age group 13 to 18 years. In a multivariate logistic regression model, patients who received an influenza vaccination were less likely to get influenza infection (OR, 0.6; 95% CI, 0.4 to 0.8; P = 0.001), with significant confounding factors such as age group 13 to 18 years (OR, 0.5; 95% CI, 0.3 to 0.8; P = 0.003) and underlying hematology-oncology disease (OR, 0.3; 95% CI, 0.1 to 0.6; P = 0.002)., Conclusion: We report moderate effectiveness of influenza vaccination in previously healthy children aged from 6 months to 12 years in the 2018-2019 season., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2021 The Korean Academy of Medical Sciences.)

Background: The objective of this study was to determine whether severity and severity change of coexisting psychiatric symptoms might affect change of complicated grief (CG) regarding the Sewol ferry disaster., Methods: Data from a cross-sectional survey were obtained 18 months (Time 1) and 30 months (Time 2) after the disaster. We ascertained sociodemographic variables and variables obtained from self-reporting questionnaires (i.e., CG, depression, anxiety, post-traumatic stress disorder [PTSD], insomnia, embitterment, and suicidal risk) among 56 bereaved family members., Results: Severity of other psychiatric symptoms at Time 1 had no effect on change of CG at Time 2. However, changes in severity of PTSD over a year affected change of CG., Conclusion: It is important to evaluate changes in severity of PTSD and its treatment during management of CG, especially when it involves bereaved families experiencing a traumatic accident., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2019 The Korean Academy of Medical Sciences.)

This study investigated the changes in the major etiologic organisms and clinical phenotypes of nontuberculous mycobacterial lung disease (NTM-LD) over a recent 15-year period in Korea. The increase of number of patients with NTM-LD was primarily due to an increase of Mycobacterium avium complex (MAC) lung disease (LD). Among MAC cases, the proportion of M. avium increased compared with M. intracellulare, whereas the incidence of M. abscessus complex and M. kansasii LD remained relatively stable. The proportion of cases of the nodular bronchiectatic form increased compared with the fibrocavitary form of NTM-LD., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2018 The Korean Academy of Medical Sciences.)

Few studies have assessed the overall effects of multi-centered, complicated mental health support on the grief process. This study investigated the broader influence of mental health support provided practically to the bereaved family on the severity of complicated grief. Ninety-three bereaved family members of the Sewol ferry accident were recruited. Severity of complicated grief, post-traumatic stress disorder (PTSD) and depressive disorder was assessed through self-reporting questionnaire, inventory of complicated grief (ICG), PTSD Check List-5 (PCL-5) and Patient Health Questionnaire-9 (PHQ-9). We also included demographic, socioeconomic, health-related variables, and Functional Social Support Questionnaire (FSSQ), which affect the ICG score. Participants were divided into 4 groups based on the experience of psychotherapy or psychiatry clinic service before the accident and mental health support after the disaster. In univariate analysis, these 4 groups showed a significant difference in the mean ICG score (P = 0.020). Participants who received mental health support only after the Sewol ferry accident (group 2) showed a lower mean ICG score than those who received neither psychotherapy or psychiatry clinic service before the disaster nor mental health support after the accident (group 4). There was no significant correlation between the ICG score and other variables except for subjective health status measured 1 month after the disaster (P = 0.005). There was no significant difference in PCL-5 (P = 0.140) and PHQ-9 scores (P = 0.603) among groups, respectively. In conclusion, mental health support significantly reduced the severity of grief only in those participants who had not received any psychotherapy or psychiatry clinic service before the accident., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2017 The Korean Academy of Medical Sciences.)

The prognostic significance of multidrug resistance (MDR) gene expression is controversial. We investigated whether multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression are associated with outcomes in acute leukemia patients. At diagnosis we examined MDR1, MRP and LRP mRNA expression in bone marrow samples from 71 acute leukemia patients (39 myeloid, 32 lymphoblastic) using nested RT-PCR. The expression of each of these genes was then expressed as a ratio in relation to beta-actin gene expression, and the three genes were categorized as being either 0, 1+, 2+ or 3+. MDR1, MRP and LRP mRNA expression was detected in 23.9%, 83.1% and 45.1 %, respectively. LRP mRNA expression was significantly associated with resistance to induction chemotherapy in acute leukemia patients, and in the AML proportion (p=0.02 and p=0.03, respectively). MRP and high MDR1 mRNA expression was associated with poorer 2-yr survival (p=0.049 and p=0.04, respectively). Patients expressing both MRP and LRP mRNA had poorer outcomes and had worse 2-yr survival. The present data suggest that MDR expression affects complete remission and survival rates in acute leukemia patients. Thus, determination of MDR gene expression at diagnosis appears likely to provide useful prognostic information for acute leukemia patients.