Severe Fever with Thrombocytopenia Syndrome in South Korea, 2016-2021: Clinical Features of Severe Progression and Complications.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infection with a high case fatality rate. The serious clinical features need to be further defined. We performed a retrospective analysis among SFTS patients in South Korea during 2016-2021 to update the current status. The basic epidemiology of all reported cases was analyzed, and the detailed clinical data of the subjects were further collected from study hospitals selected in terms of their geographic location and capability of SFTS care. Cases of SFTS were reported across the country and were greatly increased since the initial endemic phase, even under the passive surveillance system. The case fatality rate remained at approximately 16.8%. Coinfections at admission were present in 7.8% of the patients. Major complications included bleeding (15.2%), hemophagocytic lymphohistiocytosis (6.7%), bacteremia or candidemia (4.0%), and invasive pulmonary aspergillosis (1.7%). It took a median 4 days from the onset of illness to hospital admission. Rapid clinical deterioration was observed with a median 1 day for intensive care unit admission, 3 days for mechanical ventilation, 4 days for renal replacement therapy, and 5 days for death, all after the hospitalization. Multivariate analysis showed that the fatality was associated with older age, bacteremia, or candidemia during hospitalization, and the presence of several variables at admission such as fever, altered mentality, aspartate aminotransferase >200 IU/L, serum creatinine level >1.2 mg/dL, and prolonged prothrombin time and activated partial thromboplastin time. Treatment options to improve clinical outcomes are limited, despite best supportive care. Specific treatment is urgently needed to change the fatal course.

Overcoming the age-dependent SARS-CoV-2 vaccine response through hybrid immunity: analysis of humoral and cellular immunity with mass cytometry profiling.

BACKGROUND: Age-dependent immune responses to coronavirus disease 2019 (COVID-19) vaccinations and breakthrough infections (BIs) in young and middle-aged individuals are unclear. METHODS: This nationwide multicenter prospective cohort study analyzed immune responses in participants of the ChAdOx1 (ChAd)-ChAd-mRNA vaccine group using cytometry by time-of-flight, anti-spike protein antibody (Sab) and anti-nucleocapsid antibody (Nab) titers, plaque reduction neutralization tests (PRNTs), and interferon-gamma (IFN-γ) release assays at various time points. RESULTS: We evaluated 347 participants with an average age of 38.9 ± 9.4 years (range: 21-63). There was a significant inverse correlation between age and Sab levels after the second dose (slope - 14.96, P = 0.032), and this was more pronounced after the third dose (slope - 208.9, P < 0.001). After BIs, older participants showed significantly higher Sab titers (slope 398.8, P = 0.001), reversing the age-related decline observed post-vaccination. This reversal was also observed in PRNTs against wild-type SARS-CoV-2 and the BA.1 and BA.5 variants. IFN-γ responses increased markedly after the third dose and Bis, but showed a weak positive correlation with age, without statistical significance. Immune cell profiling revealed an age-dependent decrease in the proportions of B-cell lineage cells. The proportions of naive CD4+ and CD8+ T cells were inversely correlated with age, whereas the proportions of mature T cell subsets with memory function, including memory CD4+ T, CD8+ TEM, CD8+ TEMRA, and TFH cells, increased with age. CONCLUSIONS: Age-dependent waning of the serologic response to COVID-19 vaccines occurred even in middle-aged individuals, but was reversed after BIs. IFN-γ responses were preserved, compensating for the decrease in naive T cell populations, with an increase in memory T cell populations.

Comparison of HIV characteristics across 3 datasets: the Korea HIV/AIDS Cohort Study Prospective, Retrospective, and National Reporting System.

Objectives: The Korea HIV/AIDS Cohort Study has been conducted prospectively for 18 years. However, it faces limitations in representing the entire population of patients with HIV in Korea. To address these limitations and validate the study design, we analyzed characteristics across several HIV datasets. Methods: We compared epidemiological and clinical characteristics from 3 datasets: the Korea HIV/AIDS Cohort Study (dataset 1, n=1,562), retrospective cohort data (dataset 2, n=2,665), and the national HIV reporting system of the Korea Disease Control and Prevention Agency (KDCA) (dataset 3, n=17,403). Results: The demographic characteristics of age, sex, and age at HIV diagnosis did not differ significantly across datasets. However, dataset 3 contained a higher percentage of patients diagnosed after 2008 (69.5%) than the other datasets. Regarding transmission routes, same-sex contact accounted for a greater proportion of dataset 1 (59.8%) compared to datasets 2 (20.9%) and 3 (32.6%). The percentage of patients with CD4 T-cell counts below 200/mm3 at HIV diagnosis was higher in datasets 1 (39.4%) and 2 (33.3%) compared to dataset 3 (16.3%). Initial HIV viral load measurements were not obtained for dataset 3. Conclusion: The Korea HIV/AIDS Cohort Study demonstrated representativeness regarding the demographic characteristics of Korean patients. Of the sources, dataset 1 contained the most data on transmission routes. While the KDCA data encompassed all HIV patients, it lacked detailed clinical information. To improve the representativeness of the Korea HIV/AIDS Cohort Study, we propose expanding and revising the cohort design and enrolling more patients who have been recently diagnosed.

Effectiveness and Tolerability of Dual Therapy with Dolutegravir Plus Darunavir/cobicistat in Treatment-Experienced Patients with HIV: A 144-Week Follow-Up.

BACKGROUND: A dual regimen with dolutegravir plus cobicistat-boosted darunavir (DTG+DRV/c) is a promising alternative for patients with human immunodeficiency virus (HIV) with resistance or intolerance to nucleoside reverse transcriptase inhibitors, especially those with a history of treatment failure. MATERIALS AND METHODS: We included all treatment-experienced patients with HIV who switched to the DTG+DRV/c regimen at a tertiary university hospital. We assessed the regimen's effectiveness, safety, and tolerability through serial laboratory data and clinical findings. The primary endpoint was the proportion of patients with plasma HIV-RNA levels <50 copies/mL at week 144 post-switch. The secondary endpoints were safety and tolerability assessments. RESULTS: Our retrospective analysis involved 40 patients. The leading reasons for switching to DTG+DRV/c were treatment failure in 17 patients (42.5%), simplification after multiple previous regimens in 15 (37.5%), and adverse drug reactions in 8 (20.0%). Among the 17 patients in the treatment failure group, we observed enhanced viral suppression and improved CD4+ T-cell counts after initiating the dual regimen. In the non-treatment failure group (23 patients), viral suppression and CD4+ T-cell levels were consistently maintained. No significant alterations in renal function, liver function, glucose levels, or lipid profiles were observed post-switch. High tolerability was observed, with 34/40 patients (85.0%) responding well to the regimen. However, six patients discontinued treatment before reaching the 144-week mark. CONCLUSION: Our findings confirm that DTG+DRV/c is an effective and well-tolerated switch therapy regimen for treatment-experienced patients with HIV, with sustained benefits observed for up to 144 weeks of follow-up. This regimen showed adaptability across different patient groups and demonstrated virological and immunological improvements, particularly in patients with a history of treatment failure.

Clinical Outcomes of Solid Organ Transplant Recipients Hospitalized with COVID-19: A Propensity Score-Matched Cohort Study.

BACKGROUND: Solid-organ transplant recipients (SOTRs) receiving immunosuppressive therapy are expected to have worse clinical outcomes from coronavirus disease 2019 (COVID-19). However, published studies have shown mixed results, depending on adjustment for important confounders such as age, variants, and vaccination status. MATERIALS AND METHODS: We retrospectively collected the data on 7,327 patients hospitalized with COVID-19 from two tertiary hospitals with government-designated COVID-19 regional centers. We compared clinical outcomes between SOTRs and non-SOTRs by a propensity score-matched analysis (1:2) based on age, gender, and the date of COVID-19 diagnosis. We also performed a multivariate logistic regression analysis to adjust other important confounders such as vaccination status and the Charlson comorbidity index. RESULTS: After matching, SOTRs (n=83) had a significantly higher risk of high-flow nasal cannula use, mechanical ventilation, acute kidney injury, and a composite of COVID-19 severity outcomes than non-SOTRs (n=160) (all P <0.05). The National Early Warning Score was significantly higher in SOTRs than in non-SOTRs from day 1 to 7 of hospitalization (P for interaction=0.008 by generalized estimating equation). In multivariate logistic regression analysis, SOTRs (odds ratio [OR], 2.14; 95% confidence interval [CI], 1.12-4.11) and male gender (OR, 2.62; 95% CI, 1.26-5.45) were associated with worse outcomes, and receiving two to three doses of COVID-19 vaccine (OR, 0.43; 95% CI, 0.24-0.79) was associated with better outcomes. CONCLUSION: Hospitalized SOTRs with COVID-19 had a worse prognosis than non-SOTRs. COVID-19 vaccination should be implemented appropriately to prevent severe COVID-19 progression in this population.

Persistent differences in the immunogenicity of the two COVID-19 primary vaccines series, modulated by booster mRNA vaccination and breakthrough infection.

INTRODUCTION: The long-term impact of initial immunogenicity induced by different primary COVID-19 vaccine series remains unclear. METHODS: A prospective cohort study was conducted at 10 tertiary hospitals in Korea from March 2021 to September 2022. Immunogenicity assessments included anti-spike protein antibody (Sab), SARS-CoV-2-specific interferon-gamma releasing assay (IGRA), and multiplex cytokine assays for spike protein-stimulated plasma. Spike proteins derived from wild-type SARS-CoV-2 and alpha variant (Spike1) and beta and gamma variant (Spike2) were utilized. RESULTS: A total of 235 healthcare workers who had received a two-dose primary vaccine series of either ChAdOx1 or BNT162b2, followed by a third booster dose of BNT162b2 (166 in the ChAdOx1/ChAdOx1/BNT162b2 (CCB) group and 69 in the BNT162b2/BNT162b2/BNT162b2 (BBB) group, based on the vaccine series) were included. Following the primary vaccine series, the BBB group exhibited significantly higher increases in Sab levels, IGRA responses, and multiple cytokines (CCL2/MCP-1, CCL3/MIP-1α, CCL4/MIP-1ß, interleukin (IL)-1ra, IFN-γ, IL-2, IL-4, and IL-10) compared to the CCB group (all P < 0.05). One month after the third BNT162b2 booster, the CCB group showed Sab levels comparable to those of the BBB group, and both groups exhibited lower levels after six months without breakthrough infections (BIs). However, among those who experienced BA.1/2 BIs after the third booster, Sab levels increased significantly more in the BBB group than in the CCB group (P < 0.001). IGRA responses to both Spike1 and Spike2 proteins were significantly stronger in the BBB group than the CCB group after the third booster, while only the Spike2 response were higher after BIs (P = 0.007). The BBB group exhibited stronger enhancement of T-cell cytokines (IL-2, IL-4, and IL-17A) after BIs than in the CCB group (P < 0.05). CONCLUSION: Differences in immunogenicity induced by the two primary vaccine series persisted, modulated by subsequent booster vaccinations and BIs.

Antimicrobial Use and Carbapenem-Resistant Enterobacterales in Korea: A Nationwide Case-Control Study With Propensity Score Matching.

BACKGROUND: Nationwide research on the association between carbapenem-resistant Enterobacterales (CREs) and antibiotic use is limited. METHODS: This nested case-control study analyzed Korean National Health Insurance claims data from April 2017 to April 2019. Based on the occurrence of CRE, hospitalized patients aged ≥ 18 years were classified into CRE (cases) and control groups. Propensity scores based on age, sex, modified Charlson comorbidity score, insurance type, long-term care facility, intensive care unit stay, and acquisition of vancomycin-resistant Enterococci were used to match the case and control groups (1:3). RESULTS: After matching, the study included 6,476 participants (1,619 cases and 4,857 controls). Multivariable logistic regression analysis revealed that the utilization of broad-spectrum antibiotics, such as piperacillin/tazobactam (adjusted odds ratio [aOR], 2.178; 95% confidence interval [CI], 1.829-2.594), third/fourth generation cephalosporins (aOR, 1.764; 95% CI, 1.514-2.056), and carbapenems (aOR, 1.775; 95% CI, 1.454-2.165), as well as the presence of comorbidities (diabetes [aOR, 1.237; 95% CI, 1.061-1.443], hemiplegia or paraplegia [aOR, 1.370; 95% CI, 1.119-1.679], kidney disease [aOR, 1.312; 95% CI, 1.105-1.559], and liver disease [aOR, 1.431; 95% CI, 1.073-1.908]), were significantly associated with the development of CRE. Additionally, the CRE group had higher mortality (8.33 vs. 3.32 incidence rate per 100 person-months, P < 0.001) and a total cost of healthcare utilization per person-month (15,325,491 ± 23,587,378 vs. 5,263,373 ± 14,070,118 KRW, P < 0.001) than the control group. CONCLUSION: The utilization of broad-spectrum antibiotics and the presence of comorbidities are associated with increasing development of CRE. This study emphasizes the importance of antimicrobial stewardship in reducing broad-spectrum antibiotic use and CRE disease burden in Korea.

Association between obesity and cancer risk in adults with HIV in Korea.

INTRODUCTION: This study aimed to investigate the association between obesity and cancer risk as well as site-specific cancer risks in adults with HIV using a nationwide health screening database in Korea. METHODS: Of the 16,671 adults with a new diagnosis of HIV from 2004 to 2020, 456 incident cancer cases and 1814 individually matched controls by sex, year of birth, year of HIV diagnosis, and follow-up duration (1 : 4 ratio) were included in this nested case-control study. The association between obesity (BMI ≥25 kg/m 2 ) and cancer risks was estimated and presented as odds ratios (ORs) and 95% confidence intervals (95% CIs). RESULTS: Of the 456 cancer incident cases, there were 146 AIDS-defining cancer cases and 310 non-AIDS-defining cancer cases. Compared with nonobese adults with HIV, obese adults with HIV were at higher risk of non-AIDS-defining cancer (OR = 1.478, 95% CI = 1.118-1.955). Otherwise, the overall risk of AIDS-defining cancer (OR = 0.816, 95% CI = 0.520-1.279) and each type of AIDS-defining cancer (Kaposi sarcoma and non-Hodgkin's lymphoma) were not high in obese adults with HIV. Of the specific types of non-AIDS-defining cancers, obesity was associated with an increased risk of colorectal cancer (OR = 3.090, 95% CI = 1.110-8.604) and liver, bile duct, and pancreatic cancers (OR = 2.532, 95% CI = 1.141-5.617). CONCLUSION: Obesity, which is one of the important health concerns in HIV management, was associated with an increased risk of non-AIDS-defining cancer but not AIDS-defining cancer.

Principles and practices of antimicrobial stewardship programs in Korea.

This review addresses the escalating challenge posed by antibiotic resistance, highlighting its profound impact on global public health, including increased mortality rates and healthcare expenditures. The review focuses on the need to adopt the One Health approach to effectively manage antibiotic usage across human, animal, and environmental domains. Antimicrobial stewardship programs (ASPs) are considered as comprehensive strategies that encompass both core and supplementary initiatives aimed at enhancing prudent antibiotic use. The 2021 "Guidelines on Implementing ASP in Korea" introduced such strategies, with a strong emphasis on fostering multidisciplinary and collaborative efforts. Furthermore, the "Core Elements for Implementing ASPs in Korean General Hospitals," established in 2022, provide a structured framework for ASPs, delineating leadership responsibilities, the composition of interdisciplinary ASP teams, a range of interventions, and continuous monitoring and reporting mechanisms. In addition, this review examines patient-centric campaigns such as "Speak Up, Get Smart" and emphasizes the pivotal role of a multidisciplinary approach and international cooperation in addressing the multifaceted challenges associated with antibiotic resistance.

Effect of Regdanvimab on Mortality in Patients Infected with SARS-CoV-2 Delta Variants: A Propensity Score-Matched Cohort Study.

INTRODUCTION: Regdanvimab, a monoclonal antibody pharmaceutical, is the first Korean drug approved for treating coronavirus disease 2019 (COVID-19). We analyzed the therapeutic efficacy of regdanvimab in patients with the COVID-19 delta variant infection. METHODS: We retrospectively reviewed the electronic medical records of patients hospitalized at two Korean tertiary COVID-19 hospitals with COVID-19 delta variant infection between May 26, 2021, and January 30, 2022. To analyze the therapeutic efficacy of regdanvimab, the patients were divided into regdanvimab and non-regdanvimab groups and were 1:1 propensity-score (PS)-matched on age, severity at admission, and COVID-19 vaccination history. RESULTS: Of 492 patients, 262 (53.3%) and 230 (46.7%) were in the regdanvimab and non-regdanvimab groups, respectively. After PS matching the groups on age, severity at admission, and COVID-19 vaccination history, each group comprised 189 patients. The 30-day hospital mortality rates (0.0% vs. 1.6%, p = 0.030), proportions of patients with exacerbated conditions to severe/critical/died (9.5% vs. 16.4%, p = 0.047), proportions who received oxygen therapy because of pneumonia exacerbation (7.4% vs. 16.4%, p = 0.007), and proportions with a daily National Early Warning Score ≥ 5 from hospital day 2 were significantly lower in the regdanvimab group. CONCLUSIONS: We showed that regdanvimab reduced the exacerbation rates of conditions and mortality in patients with the COVID-19 delta variant infection. Thus, it is recommended to streamline the drug approval system during epidemics of new variant viruses to improve the availability and usage of therapeutics for patients. To facilitate this, relevant institutional support is required.

Prevalence and Associated Factors of Depression and Anxiety Among Healthcare Workers During the Coronavirus Disease 2019 Pandemic: A Nationwide Study in Korea.

BACKGROUND: A healthcare system's collapse due to a pandemic, such as the coronavirus disease 2019 (COVID-19), can expose healthcare workers (HCWs) to various mental health problems. This study aimed to investigate the impact of the COVID-19 pandemic on the depression and anxiety of HCWs. METHODS: A nationwide questionnaire-based survey was conducted on HCWs who worked in healthcare facilities and public health centers in Korea in December 2020. Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) were used to measure depression and anxiety. To investigate factors associated with depression and anxiety, stepwise multiple logistic regression analysis was performed. RESULTS: A total of 1,425 participating HCWs were included. The mean depression score (PHQ-9) of HCWs before and after COVID-19 increased from 2.37 to 5.39, and the mean anxiety score (GAD-7) increased from 1.41 to 3.41. The proportion of HCWs with moderate to severe depression (PHQ-9 ≥ 10) increased from 3.8% before COVID-19 to 19.5% after COVID-19, whereas that of HCWs with moderate to severe anxiety (GAD-7 ≥ 10) increased from 2.0% to 10.1%. In our study, insomnia, chronic fatigue symptoms and physical symptoms after COVID-19, anxiety score (GAD-7) after COVID-19, living alone, and exhaustion were positively correlated with depression. Furthermore, post-traumatic stress symptoms, stress score (Global Assessment of Recent Stress), depression score (PHQ-9) after COVID-19, and exhaustion were positively correlated with anxiety. CONCLUSION: In Korea, during the COVID-19 pandemic, HCWs commonly suffered from mental health problems, including depression and anxiety. Regularly checking the physical and mental health problems of HCWs during the COVID-19 pandemic is crucial, and social support and strategy are needed to reduce the heavy workload and psychological distress of HCWs.

Characteristics of long COVID and the impact of COVID-19 vaccination on long COVID 2 years following COVID-19 infection: prospective cohort study.

This prospective cohort study aimed to identify characteristics of long COVID and any potential mitigating effects of COVID-19 vaccinations in patients 24 months following COVID-19 infection. Adult patients diagnosed with COVID-19 between February 17, 2020, and March 24, 2020, were scheduled to visit the study hospital four times (6, 12, 18, and 24 months after infection) to assess their symptoms, quality of life, and mental health. Among the 235 patients, 121 (51.5%) completed the study visits. Of these, 59.5% were female, with a median age of 52 years. Mild to moderate disease severity were identified in 101 (83.4%) patients. A total of 75 participants (62.0%) were still experiencing long COVID symptoms 24 months after acute infection. Fatigue, amnesia, difficulty concentrating, and insomnia were the most common symptoms. The frequency of neuropsychiatric symptoms did not differ based on vaccination status or the number of doses received. Quality of life improved over time for the participants, but 32.2% of respondents still reported anxiety/depression at the end of the study. Overall, our cohort demonstrates that long COVID can persist up to 24 months after COVID-19 infection, affecting mental health and quality of life.

Clinical utility of quantitative immunoassays and surrogate virus neutralization tests for predicting neutralizing activity against the SARS-CoV-2 Omicron BA.1 and BA.5 variants.

Developing new antibody assays for emerging SARS-CoV-2 variants is challenging. SARS-CoV-2 surrogate virus neutralization tests (sVNT) targeting Omicron BA.1 and BA.5 have been devised, but their performance needs to be validated in comparison with quantitative immunoassays. First, using 1749 PRNT-positive sera, we noticed that log-transformed optical density (OD) ratio of wild-type (WT) sVNT exhibited better titer-correlation with plaque reduction neutralization test (PRNT) than % inhibition value. Second, we tried 798 dilutional titration tests with 103 sera, but nonlinear correlation between OD ratio and antibody concentration limited titration of sVNT. Third, the titer-correlations of two sVNT kits for BA.1 and two quantitative immunoassays for WT were evaluated with BA.1 and BA.5 PRNT. All tested kits exhibited a linear correlation with PRNT titers, but the sVNT kits exhibited high false-negative rates (cPass-BA.1 kit, 45.4% for BA.1 and 44.2% for BA.5; STANDARD F-BA.1 kit, 1.9% for BA.1 and 2.2% for BA.5), while quantitative immunoassays showed 100% sensitivity. Linear mixed-effects model suggested superior titer-correlation with PRNT for quantitative immunoassays compared to sVNT kits. Taken together, the use of quantitative immunoassays for WT, rather than rapid development of new kits, would be practical for predicting neutralizing activities against emerging new variants.

The clinical course of hospitalized COVID-19 patients and aggravation risk prediction models: a retrospective, multi-center Korean cohort study.

Background: Understanding the clinical course and pivotal time points of COVID-19 aggravation is critical for enhancing patient monitoring. This retrospective, multi-center cohort study aims to identify these significant time points and associate them with potential risk factors, leveraging data from a sizable cohort with mild-to-moderate symptoms upon admission. Methods: This study included data from 1,696 COVID-19 patients with mild-to-moderate clinical severity upon admission across multiple hospitals in Daegu-Kyungpook Province (Daegu dataset) between February 18 and early March 2020 and 321 COVID-19 patients at Seoul Boramae Hospital (Boramae dataset) collected from February to July 2020. The approach involved: (1) identifying the optimal time point for aggravation using survival analyses with maximally selected rank statistics; (2) investigating the relationship between comorbidities and time to aggravation; and (3) developing prediction models through machine learning techniques. The models were validated internally among patients from the Daegu dataset and externally among patients from the Boramae dataset. Results: The Daegu dataset showed a mean age of 51.0 ± 19.6 years, with 8 days for aggravation and day 5 being identified as the pivotal point for survival. Contrary to previous findings, specific comorbidities had no notable impact on aggravation patterns. Prediction models utilizing factors including age and chest X-ray infiltration demonstrated promising performance, with the top model achieving an AUC of 0.827 in external validation for 5 days aggravation prediction. Conclusion: Our study highlights the crucial significance of the initial 5 days period post-admission in managing COVID-19 patients. The identification of this pivotal time frame, combined with our robust predictive models, provides valuable insights for early intervention strategies. This research underscores the potential of proactive monitoring and timely interventions in enhancing patient outcomes, particularly for those at risk of rapid aggravation. Our findings offer a meaningful contribution to understanding the COVID-19 clinical course and supporting healthcare providers in optimizing patient care and resource allocation.