Background: To address the public’s fear of coronavirus disease 2019 (COVID-19), understanding the clinical features of the disease is essential. However, research on the clinical features of COVID-19, including illness duration and post-acute COVID-19, in Korean pediatric patients has been limited. Therefore, this study investigated the clinical features of COVID-19 based on the medical records of pediatric patients with a history of COVID-19 who visited a single center. Methods: In total, 311 patients were included in this study. The presence and duration of 19 symptoms were examined. Additionally, clinical features were investigated by dividing the patients into different age ranges. Patients aged 6 and above were further categorized according to the presence of asthma, while adolescent patients were divided into vaccinated and unvaccinated groups. Results: Fever and cough were the most common symptoms. The mean illness duration was 2–4 days. Only 3.5% of the patients were asymptomatic. Post-acute COVID-19 was observed in 13.2% of the patients. The incidence of most symptoms tended to increase with age. Post-acute COVID-19 was observed more frequently in patients with asthma than in those without asthma. Vaccinated patients experienced less fever, vomiting, and fatigue than unvaccinated patients. Conclusions Our data suggest that most patients had mild disease lasting less than a week, and the clinical course may differ depending on the presence of asthma. The findings also indicate that vaccination may alleviate the symptoms of COVID-19 in breakthrough infections.

PURPOSE: This study aimed to examine the association between the maximum standardized uptake value (SUVmax) of different molecular subtypes of primary breast cancer with axillary lymph node (ALN) metastasis. METHODS: The medical records of 633 patients, who underwent 18F-fluorodeoxyglucose positron emission tomography-computed tomography (PET/CT) for preoperative staging, were retrospectively reviewed. The cohort was stratified by the following molecular subtypes with immunohistochemical examination: luminal A, luminal B, human epidermal growth factor receptor 2 positive (HER2+), and triple negative. We evaluated the optimal cutoff SUVmax to predict ALN metastasis in each subtype using the receiver operating characteristic (ROC) analysis. Moreover, the risk factors for ALN metastasis were evaluated. RESULTS: Overall, the SUVmax was positively correlated with the number of metastatic ALN (p=0.001). The mean SUVmax was higher in aggressive subtypes (4.5±0.2, 6.1±0.4, 6.5±0.5, and 7.5±0.5 in luminal A, luminal B, HER2+, and triple negative, respectively, p<0.001). Upon ROC analysis, the SUVmax of the HER2+ subtype predicted ALN metastasis most accurately, with a cutoff value of 5.5, area under the curve (AUC) of 0.708, sensitivity of 74.2%, and specificity of 64.6% (p=0.002). The triple negative subtype did not show a significant difference in SUVmax between patients with and without metastasis (p=0.13). Subtype-adjusted SUVmax, HER2 positivity, lymphovascular invasion, and T stage were significant predictors for ALN metastasis. CONCLUSION The SUVmax of primary breast cancer may be an independent predictor of ALN metastasis, being the most accurate in the HER2+ subtype. As PET/CT could facilitate tailored axillary management, this approach could be considered for the initial staging and treatment planning in patients with breast cancer.