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IMPORTANCE There is limited information describing the full spectrum of coronavirus disease 2019 (COVID-19) and the duration of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA detection in children. OBJECTIVE To analyze the full clinical course and the duration of SARS-CoV-2 RNA detectability in children confirmed with COVID-19 in the Republic of Korea, where rigorous public health interventions have been implemented. DESIGN, SETTING, AND PARTICIPANTS This case series of children with COVID-19 was conducted in 20 hospitals and 2 nonhospital isolation facilities across the country from February 18, 2020, to March 31, 2020. Children younger than 19 years who had COVID-19 were included. EXPOSURES Confirmed COVID-19, detected via SARS-CoV-2 RNA in a combined nasopharyngeal and oropharyngeal swab or sputum by real-time reverse transcriptionpolymerase chain reaction. MAIN OUTCOMES AND MEASURES Clinical manifestations during the observation period, including the time and duration of symptom occurrence. The duration of SARS-CoV-2 RNA detection was also analyzed. RESULTS A total of 91 children with COVID-19 were included (median [range] age, 11 [0-18] years; 53 boys [58%]). Twenty children (22%) were asymptomatic during the entire observation period. Among 71 symptomatic cases, 47 children (66%) had unrecognized symptoms before diagnosis, 18 (25%) developed symptoms after diagnosis, and only 6 (9%) were diagnosed at the time of symptom onset. Twenty-two children (24%) had lower respiratory tract infections. The mean (SD) duration of the presence of SARS-CoV-2 RNA in upper respiratory samples was 17.6 (6.7) days. Virus RNA was detected for a mean (SD) of 14.1 (7.7) days in asymptomatic individuals. There was no difference in the duration of virus RNA detection between children with upper respiratory tract infections and lower respiratory tract infections (mean [SD], 18.7 [5.8] days vs 19.9 [5.6] days; P = .54). Fourteen children (15%) were treated with lopinavir-ritonavir and/or hydroxychloroquine. All recovered, without any fatal cases. CONCLUSIONS AND RELEVANCE In this case series study, inapparent infections in children may have been associated with silent COVID-19 transmission in the community. Heightened surveillance using laboratory screening will allow detection in children with unrecognized SARS-CoV-2 infection.

Coronavirus disease-2019 (COVID-19), which started in Wuhan, China, in December 2019 and declared a worldwide pandemic on March 11, 2020, is a novel infectious disease that causes respiratory illness and death. Pediatric COVID-19 accounts for a small percentage of patients and is often milder than that in adults; however, it can progress to severe disease in some cases. Even neonates can suffer from COVID-19, and children may spread the disease in the community. This review summarizes what is currently known about COVID-19 in children and adolescents.

Adiponectin is associated with obesity and insulin resistance. To date, there has been no genome-wide association study (GWAS) of adiponectin levels in Asians. Here we present a GWAS of a cohort of Korean volunteers. A total of 4,001 subjects were genotyped by using a genome-wide marker panel in a two-stage design (979 subjects initially and 3,022 in a second stage). Another 2,304 subjects were used for follow-up replication studies with selected markers. In the discovery phase, the top SNP associated with mean log adiponectin was rs3865188 in CDH13 on chromosome 16 (p = 1.69 × 10(-15) in the initial sample, p = 6.58 × 10(-39) in the second genome-wide sample, and p = 2.12 × 10(-32) in the replication sample). The meta-analysis p value for rs3865188 in all 6,305 individuals was 2.82 × 10(-83). The association of rs3865188 with high-molecular-weight adiponectin (p = 7.36 × 10(-58)) was even stronger in the third sample. A reporter assay that evaluated the effects of a CDH13 promoter SNP in complete linkage disequilibrium with rs3865188 revealed that the major allele increased expression 2.2-fold. This study clearly shows that genetic variants in CDH13 influence adiponectin levels in Korean adults.

Epidemiologic data suggest a strong association between low birth weight and increased risk of metabolic syndrome in adult life. However, the underlying mechanisms are largely unknown. To test the hypothesis that mitochondrial changes may serve as a link between poor nutrition in early life and insulin resistance in later life, we investigated the effect of protein malnutrition during gestation and lactation on mitochondria of the liver and skeletal muscle. Female offspring of Sprague-Dawley rats fed a low protein diet (casein, 80 g/kg) were randomly divided into two groups and weaned onto either the low protein diet or a control diet (casein, 180 g/kg). As a control group, offspring of rats fed the control diet were weaned onto the control diet. The rats in each group were randomly divided into four groups that were killed at 5, 10, 15 and 20 wk of age. Both mitochondrial DNA content and the expression of mitochondrial DNA-encoded genes in liver and muscle were measured. Mitochondrial transcription factor A and antioxidant enzyme activities were also determined. The mitochondrial DNA content of the liver and skeletal muscle were reduced in fetal and early postnatal malnourished rats even when proper nutrition was supplied after weaning. These changes were accompanied by a decrease in mitochondrial DNA-encoded gene expression; however, they were not dependent on mitochondrial transcriptional factor A. Our findings indicate that poor nutrition in early life causes long-lasting changes in mitochondria that may contribute to the development of insulin resistance in later life.

The prevalence of HCV infection is low in South Korea. Studies to analyse risk factors are warranted to reduce HCV infection.

These results suggest that sequence variations in SLC1A1 are associated with susceptibility to AAP-induced OC symptoms. This is the first published pharmacogenetic study on this phenomenon and provides preliminary evidence of the involvement of glutamatergic neurotransmission in the pathogenesis of AAP-induced OC symptoms.

In Korea, Mycoplasma pneumoniae was detected in 255/2,089 respiratory specimens collected during 2000–2011; 80 isolates carried 23S rRNA gene mutations, and 69/123 culture-positive samples with the mutation were resistant to 5 macrolides. During 2000–2011, prevalence of the mutation increased substantially. These findings have critical implications for the treatment of children with mycoplasma pneumonia.