Won Seok Lee

Background: The COVID‐19 pandemic disrupted the seasonal patterns of pediatric respiratory infections, likely due to an immunologic gap. However, the roles of weather conditions and viral interactions in age‐specific transmission, seasonality, and coinfections remain unclear. Methods: This retrospective study analyzed data from children hospitalized with respiratory tract infections between January 2012 and December 2023 at a single tertiary center in Korea. Six common respiratory viruses were identified via multiplex polymerase chain reaction (PCR). The study period was divided into prepandemic (January 2012 to January 2020), pandemic (February 2020 to November 2021), and postpandemic (December 2021 to December 2023) periods. Pandemic‐period patients ( n = 171) were excluded from comparative analyses. Virus positivity, coinfection rates, and demographic differences were assessed using chi‐square tests and t ‐tests. Time‐series analysis using seasonal autoregressive integrated moving average models (SARIMA and SARIMAX) was conducted to compare observed and predicted trends. Results: Among 12,306 hospitalized children, 86.3% were in the prepandemic period and 12.3% in the postpandemic period. Median age rose from 20.0 to 27.0 months. Rhinovirus (21.3%–43.7%) and human metapneumovirus (6.6%–9.6%) increased, while influenza declined (4.8%–2.8%). Seasonal patterns shifted, with higher positivity in summer and autumn. Observed trends diverged from SARIMAX predictions, suggesting changes not fully explained by the meteorological variables included in the model. Coinfections with three or more viruses rose (1.7%–3.0%), and virus‐negative proportions decreased (32.6%–16.7%). RSV showed three peaks in the postpandemic period, suggesting possible shifts in viral cocirculation patterns. Conclusion: Shifts in pediatric respiratory virus patterns were observed in the postpandemic period and were not fully explained by meteorological variables alone, highlighting the need for adaptive surveillance incorporating broader environmental and demographic factors.

Background/Objectives: Respiratory viral infections are a major cause of asthma exacerbations. However, studies examining the association between symptoms, signs, treatments, outcomes of asthma exacerbations, and various respiratory viruses in children are limited. This study aims to investigate the association between respiratory viral infections and clinical symptoms and signs, treatment, and hospital admission in children with asthma exacerbations visiting the pediatric emergency department. Methods: This study examined 395 children under 15 years of age who had a previous diagnosis of bronchial asthma, experienced asthma exacerbation, and visited an emergency center between 1 July 2015 and 30 June 2017. Among the 395 participants, respiratory virus polymerase chain reaction (PCR) was conducted in 96 patients (24.3%). The symptoms and signs of asthma exacerbation (dyspnea, tachypnea, chest retraction, wheezing, and gastrointestinal symptoms), treatment (oxygen supplementation and systemic steroid administration), symptom relief within 1 h, and hospital admission were analyzed. Results: Among the 96 patients who underwent respiratory virus PCR, at least one respiratory virus was detected in 72 (75.0%), and over two viruses were detected in 21 children (21.9%). Three common viruses were detected: rhinovirus in 59 (61.5%), adenovirus in 10 (10.4%), and respiratory syncytial virus (RSV) in nine children (9.4%). Rhinovirus infection was associated with tachypnea (adjusted odd ratio (aOR) 4.457, p = 0.007), chest retraction (aOR 3.142, p = 0.013), and systemic steroid administration (aOR 3.065, p = 0.034). Adenovirus infection was associated with oxygen supplementation via nasal cannula (aOR 5.297, p = 0.042). Conclusions: Rhinovirus was associated with tachypnea, chest retraction, and systemic steroid administration, while adenovirus was linked to oxygen supplementation in childhood asthma exacerbations. These findings will help clinicians to better observe asthma symptoms, select appropriate treatments, and improve outcomes for asthma exacerbations.

Background: The complementary food introduction and consumption guidelines for atopic dermatitis and food allergy prevention have evolved; however, their impact on infant feeding practices remains unclear. This study aimed to analyze complementary food diversity trends in infants, identify vulnerable infants with limited food diversity, and examine the trends in infants with or without vulnerable factors over time. Methods: This study analyzed infants aged 9–12 months who participated in the food diversity survey, conducted as part of the National Health Screening Program in Korea from 2009 to 2020. The complementary food items included grains, vegetables, fruits, eggs, fish, and meats. Infants consuming “six” and “less than six” complementary food items were categorized into high- and low-food-diversity groups, respectively. The study employed logistic regression models to examine the trends in food diversity and vulnerable factors with an assessment of the interaction effects. Results: This study included 3,425,301 participants (51.5% male) aged 11.3 months (standard deviation, 0.8). The high-food-diversity prevalence significantly increased over time, from 30.8% in 2009 to 52.9% in 2020 (p < 0.001). Vulnerable infants included those with preterm birth, low birth weight, non-breastfeeding status, high socioeconomic status, non-Seoul residence at birth, any perinatal conditions, hospitalization due to wheezing, atopic dermatitis and food allergies. The high-diversity proportion increased significantly over the study period across all vulnerable factors (p for interaction < 0.001). However, no significant interactions were observed between the study years and vulnerable factors, except for food allergy (β Coefficient, −0.0117, p for interaction = 0.004). Conclusions: The increasing trends in high-complementary-food-diversity proportions highlight the substantial progress over the study period. However, persistent disparities in vulnerable populations underline the importance of targeted interventions, including tailored nutritional education and policies, that promote equitable dietary practices during early life.

Background: Although atopic dermatitis (AD) in children affects diverse stages of life, no studies have reported on the association between school readiness and AD.Methods: This study used Korean National Health Insurance data and the Health Screening Program for Infants and Children. Among all children born between 2008 and 2012 in Korea, those who were assessed for school readiness through questionnaires in a health screening program performed at 54 and 60 months old were enrolled. AD was defined based on the International Classification of Diseases codes, with two or more prescriptions of topical corticosteroids during the first 54–60 months of life. The primary outcome was the association between school readiness and AD. The questionnaire relating to school readiness comprised six items – cognitive skills, social development, activeness, concentration, emotional development, and language skills. Logistic regression analysis was used to identify the associations between school readiness and AD.Results: This study included 239,673 children without AD and 38,229 children with AD. The average age at which school readiness was assessed was 4.8 years. AD was associated with vulnerability in activeness (adjusted odds ratio: 1.127; 95% confidence interval: 1.071–1.186) and concentrations (1.170; 1.093–1.254). The impact of AD on concentrations showed consistent results regardless of sex, exposure to systemic corticosteroids and antihistamines, and age at the diagnosis of AD.Conclusions: Children with AD have vulnerability in school readiness in the aspects of activeness and concentration.

Anaphylaxis is a serious life‐threatening allergic disease in children. This study is aimed at determining the characteristics of pediatric patients who experienced anaphylaxis along with treatments administered in order to determine the usefulness of tryptase level assessment as a marker of anaphylaxis in Korean children. A total of 107 patients who were diagnosed with anaphylaxis in a single pediatric emergency center over a 3‐year period were included in the study. Patient clinical characteristics, symptoms, signs, allergy history, trigger factors, treatments, and laboratory findings, including serum tryptase levels, were included in the analysis. Food allergies (39.3%) were the most commonly reported patient allergic history, and 58 patients (54.2%) were triggered by food. Among this group, nuts and milk exposure were the most common, affecting 15 patients (25.9%). History of anaphylaxis and asthma were more common in severe anaphylaxis compared to mild or moderate anaphylaxis cases. Epinephrine intramuscular injection was administrated to 76 patients (71.0%), and a self‐injectable epinephrine was prescribed to 18 patients (16.8%). The median tryptase level was 4.80 ng/mL (range: 2.70–10.40) which was lower than the 11.4 ng/mL value commonly documented for standard evaluation in adults with anaphylaxis. The most common cause of pediatric anaphylaxis was food including nuts and milk. The rate of epinephrine injection was relatively high in our pediatric emergency department. The median tryptase level associated with anaphylaxis reactions in children was lower than 11.4 ng/mL. Further studies are needed to help improve diagnostic times and treatment accuracy in pediatric patients who develop anaphylaxis.

Han J, et al. J Korean Ophthalmol Soc. 2019 Mar;60(3):233-238. https://doi.org/10.3341/jkos.2019.60.3.233

Lee WS, et al. Neonatal Med. 2013 May;20(2):221-227. http://dx.doi.org/10.5385/nm.2013.20.2.221