Sung Min Lim

Infection remains a leading cause of mortality among transplant recipients. Studies on vaccine-preventable diseases (VPDs) among transplant recipients in Asia are lacking. This study aimed to investigate the incidence and risk of VPD in transplant recipients in Korea. Individuals who underwent transplantation were retrospectively recruited using data from the Korea National Health Insurance system from 2008 to 2020. We selected four major VPDs-varicella, invasive pneumococcal disease (IPD), mumps, and pertussis-and evaluated the cumulative incidence rate and standardized incidence ratio (SIR), comparing it to that of the general population. A total of 55,363 transplant recipients were included. Among these, 1,503 cases of the four VPDs were identified. Multivariable analysis revealed a significantly higher risk of varicella in children and allogeneic hematopoietic stem cell transplantation recipients. Conversely, for IPD, the risk was higher among individuals aged ≥60 years and in solid organ transplantation recipients; however, the difference was not significant. The SIR for varicella was notably higher in adult recipients aged ≥ 20 years (SIR, 2.79; 95% confidence interval [CI], 2.53-3.06; SIR, 6.02; 95% CI, 4.89-7.33), while for IPD, the SIR for all ages was notably increased at 20.3 (95% CI, 18.72-21.96). For mumps, the SIR was significantly lower at 0.24 (95% CI, 0.19-0.30) across all age groups. Conversely, for pertussis, the SIR was 0.67 (95% CI, 0.32-1.24), but the difference was not significant. These findings underscore that transplant recipients are still at higher risk of getting VPDs than is the general population, emphasizing the importance of surveillance and vaccination efforts.

Lim SM, et al. J Korean Med Sci. 2026 Oct;41:e253. https://doi.org/10.3346/jkms.2026.41.e253

Kawasaki disease (KD), a major form of pediatric vasculitis, remains the leading cause of acquired heart disease in children in Korea. Large-scale administrative databases, such as the National Health Insurance Service (NHIS) and Health Insurance Review and Assessment Service (HIRA), have become key resources for KD research owing to their nationwide coverage and accessibility. However, these databases lack detailed clinical variables, underscoring the complementary need for registry-based datasets, such as the Korea Society of Kawasaki Disease (KSKD) survey. In this scoping review of KD research in Korea using national health data sources, we sought to map study designs, data utilization, and research themes over time and to clarify the distinct role and continuing necessity of survey-based efforts, such as the KSKD registry. Thirty three peer-reviewed studies on KD published between 2014 and 2025 were reviewed, each of which was categorized according to its data source (e.g., NHIS, HIRA, KSKD survey, and Korean Kawasaki Disease Genetic Consortium [KKDGC]), research design (e.g., cohort, cross-sectional, case-control, and ecological), and primary research theme (e.g., epidemiology, diagnosis, genetics, or complications). Temporal and cross-sectional trends were examined using descriptive tables and visual summaries. The NHIS and HIRA were the predominant data sources for epidemiological and risk factor analyses. In contrast, the KSKD survey uniquely supported studies on diagnostic classification, intravenous immunoglobulin responsiveness, and coronary complications, which require detailed clinical information that is not available in the administrative data. Although research topics had diversified in recent years, the number of clinically detailed investigations remained limited. In sum, this scoping review outlines the evolving landscape of KD research using national health databases in Korea and highlights the indispensable role of the KSKD survey. Continued methodological and institutional support for survey-based clinical datasets is essential to enhance the depth, quality, and translational relevance of KD research in the country.

Despite the decline in the overall birth rate, increasing preterm births and associated medical costs pose a national concern. We analyze hospitalization costs covered by national public insurance for preterm infants. Population-based data, obtained from the National Health Insurance Service (NHIS), which is operated by the Health Insurance Review and Assessment Service, were used for the study. Preterm births from January 1, 2008 to December 31, 2020 were included, using International Classification of Diseases and Related Health Problems, 10th edition (P07.2, extremely preterm < 28 weeks gestational age, P07.3, non-extremely preterm). The primary outcomes related to cost from the first hospitalization due to preterm births and medication, and laboratory, radiological, and functional tests by gestational age and birth weight. Additionally, we assessed the readmission rates of preterm infants and the associated medical costs. A total of 5,312,886 live infants were born, of which 90,575 were claimed as preterm birth hospitalization. The total medical cost per patient increased almost three-fold from $7,390.90 to $20,209.59 from 2008 to 2020; for the extremely preterm group, it increased four-fold ($13,961.03 to $55,984.47). The readmission rate within 90 days of discharge was 62.5%; however, a greater proportion of the extremely preterm, as compared to the non-extremely preterm (16.1% vs. 8.32%, P < 0.001) group was readmitted within 30 days. The extremely preterm group also incurred higher costs associated with readmission (mean $4293.8 vs. $2975.4, P < 0.001). This study reveals not only the increase in preterm birth rate in South Korea, but also in the associated medical costs. Further attention should be paid to efficient resource allocation at the national level to relieve the medical burden of preterm births.

Lee JY, et al. Pediatr Infect Vaccine. 2024 Apr;31(1):25-36. https://doi.org/10.14776/piv.2024.31.e1

Lin CY, et al. Pediatr Infect Vaccine. 2024 Apr;31(1):130-135. https://doi.org/10.14776/piv.2024.31.e2

Live immunization is contraindicated in patients with DiGeorge syndrome (DGS). We retrospectively investigated the occurrence of adverse events after live immunization in patients with DGS in Korea. The data of patients matching the International Classification of Disease-10 code of DGS (D82.1) at Severance Hospital Seoul, Korea, were extracted; patients without genetically diagnosed DGS were excluded. Based on T cell immunity status, the included patients were categorized into group A (CD3 < 500 or CD8 < 200 cells/mm³); group B (CD3 ≥ 500 and CD8 ≥ 200 cells/mm³); or group C (unknown). Among 94 patients, 38 (~40%, group A: 8 [21%]; group B: 30 [79%]) underwent immunological testing and 73 (~80%) received at least one live immunization (measles–mumps–rubella vaccination was most common [66/94, ~70%]). Fifty adverse events (fever [n = 29], upper respiratory infection [n = 9], diarrhea [n = 4], rash [n = 3], thrombocytopenia [n = 3], injection site pus [n = 1], and febrile convulsion [n = 1]) were observed; 13 (26%) occurred in group A, with no significant difference in incidence between groups A and B. Serious adverse events, including intensive care unit hospitalization or death, or diseases due to vaccine strains were not observed. In this study, live immunization was well tolerated by patients with partial DGS.

Kim SJ, et al. Yonsei Med J. 2022 Nov;63:e27. https://doi.org/10.3349/ymj.2022.0388

Purpose: Kikuchi–Fujimoto disease (KFD) is a rare, benign, and self-limited disease, characterized by cervical lymphadenopathy and fever. Herein, we analyzed the differences in its clinical manifestations and risk factors for recurrence between children and adults. Patients and Methods: We retrospectively reviewed the medical records of patients diagnosed with KFD at a tertiary referral hospital between 2005 and 2019. Patients were divided into two groups based on their age: children (< 19 years) and adults (≥ 19 years). Results: During the 14-year study period, 127 patients were diagnosed with KFD. Among these, 34 (26.8%) were children and 93 (73.2%) were adults. The fever duration was longer and the frequency of myalgia was higher in adults than in children; however, no other significant symptomatic differences were noted between the two groups. Lymph node evaluation was mainly performed using ultrasound in children (61.8%) and computed tomography in adults (78.5%). Moreover, the frequency of antibiotic use was higher in children than in adults (76.5% vs 54.8%, P = 0.027). In adults, multivariable logistic regression analysis revealed anti-nuclear antibody (ANA) positivity (titer ≥ 1:80) as a risk factor for recurrence (odds ratio: 7.813; 95% confidence interval = 1.818– 33.333; P = 0.006). Conclusion: The clinical features of KFD in children and adults were similar; however, the preferred imaging study and frequency of antibiotic use differed significantly between the two groups. Furthermore, in adults, ANA positivity was associated with KFD recurrence. Thus, patients with KFD who present with ANA positivity at diagnosis will benefit from a regular follow-up for monitoring KFD recurrence.

Su Min Lee, M.D., Hyungwook Choi, M.D., Sungmin Lim, M.D., Jehee Shin, M.D., Ji-Man Kang, M.D., Ph.D., Jong Gyun Ahn, M.D., Ph.D.. J Rheum Dis 2022;29:181-6. https://doi.org/10.4078/jrd.2022.29.3.181