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Background The immunologic features of children with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are not clearly delineated. This study was conducted to evaluate SARS-CoV-2-specific antibody responses in children with COVID-19. Methods The levels of anti-spike (S) IgG, anti-SARS-CoV-2 IgG, and neutralizing antibody (NAb) were measured during various time points in children Results One hundred sixty-five blood samples from 114 children with COVID-19 (43.9% asymptomatic and 56.1% mildly symptomatic) were analyzed. In both asymptomatic and mildly symptomatic children, the positive rates of anti-S IgG, anti-SARS-CoV-2 IgG, and NAb were low within 7 days after onset, but they soon reached 100% 14 to Conclusions These results collectively present the humoral immune responses during SARS-CoV-2 infection in children. A further longitudinal study is needed to thoroughly understand the immune system and for effective vaccine development in children during the COVID-19 pandemic.

Background Human adenovirus (HAdV) is a common cause of respiratory tract infection (RTI) and clinical presentation varies by serotype. Serotypes 7 and 55 caused severe pneumonia in children during the early 2000s and in soldiers from 2014 to 2018, respectively, in South Korea. Recent data for the epidemiologic and clinical features of HAdV in Korean children are scarce. Methods Nasal aspirates were collected from patients aged 18 years or younger with suspected RTIs at Seoul National University Children's Hospital from 2008 to 2019. HAdV serotype was determined by partial sequencing of hexon gene. The demographics and clinical features were reviewed through medical records. Results A total of 186 HAdVs were randomly selected for serotyping among 503 isolates obtained for 12 years. The median age was 2.1 years (range 1 month -17.9 years) with a slight male dominance (60.8%). Ten different serotypes were identified, which included 1-7, 31, 34, 35, and 55. The most predominant serotype was HAdV-3 (n=73, 39.3%) followed by HAdV-2 (n=42, 22.6%). Lower RTI was common in children infected with HAdV-3 (n=40, 54.8%) and HAdV-2 (n=18, 42.9%). HAdV-3 showed an epidemic every three years. HAdV-7 which previously caused severe pneumonia, has not been detected since 2008. HAdV-55 (n=9, 4.9%) was sporadically detected by each one case in 2008, 2009, and 2014, while six cases were detected in 2017-18. Among children with HAdV-55 detected, most (66.7%) had upper RTI as clinical diagnosis and only two (22.2%) had a clinically considerable pneumonia. Conclusion Over the past 12 years, HAdV-3 and 2 were prevalent and played an important role in RTIs of Korean children. HAdV-55 infection in children was not clinically significant in comparison to the recent Korean military outbreak cases. Disclosures All Authors: No reported disclosures.

Supplemental Digital Content is available in the text., Background: Invasive bacterial infection (IBI) remains a major burden of mortality and morbidity in children. As coronavirus disease 2019 (COVID-19) emerged, stringent nonpharmaceutical interventions (NPIs) were applied worldwide. This study aimed to evaluate the impact of NPIs on pediatric IBI in Korea. Methods: From January 2018 to December 2020, surveillance for pediatric IBIs caused by 9 pathogens (S. pneumoniae, H. influenzae, N. meningitidis, S. agalactiae, S. pyogenes, S. aureus, Salmonella species, L. monocytogenes and E. coli) was performed at 22 hospitals throughout Korea. Annual incidence rates were compared before and after the COVID-19 pandemic. Results: A total of 651 cases were identified and the annual incidence was 194.0 cases per 100,000 in-patients in 2018, 170.0 in 2019 and 172.4 in 2020. Most common pathogen by age group was S. agalactiae in infants < 3 months (n = 129, 46.7%), S. aureus in 3 to < 24 months (n = 35, 37.2%), Salmonella spp. in 24 to < 60 months (n = 24, 34.8%) and S. aureus in children ≥ 5 years (n = 128, 60.7%). Compared with 2018 to 2019, the incidence rate in 2020 decreased by 57% for invasive pneumococcal disease (26.6 vs. 11.5 per 100,000 in-patients, P = 0.014) and 59% for Salmonella spp. infection (22.8 vs. 9.4 per 100,000 in-patients, P = 0.018). In contrast, no significant changes were observed in invasive infections due to S. aureus, S. agalactiae and E. coli. Conclusions: The NPIs implemented during the COVID-19 pandemic reduced invasive diseases caused by S. pneumoniae and Salmonella spp. but not S. aureus, S. agalactiae and E. coli in children.

Background Nasopharyngeal (NP) colonization with Streptococcus pneumoniae and non-typeable Haemophilus influenzae (NTHi) is common in children, and may evolve as the source of invasive infections. In Korea, the pneumococcal conjugate vaccines (PCVs) were introduced >10 years ago, enabling the authors to study the effect of the vaccine in preventing carriage. Methods NP swabs were taken and a household survey was conducted at daycare centres located in different regions of Korea in 2014 and 2019. Pneumococcal serotypes were identified using the Quellung method and sequencing. NTHi were identified based on pilA and bexA genes. Results In total, 1460 NP swabs were obtained with pneumococcal carriage rates of 36.4–42.1% and NTHi carriage rates of 36.5–26.7%. Among children carrying pneumococci, a significant increase was seen in serotype 23A between 2014 and 2019 (from 12.6% to 22.0%; P=0.005). Children who had received PCV were at lower risk of vaccine-type carriage (2.9% vs 0.8%; P=0.005). Conclusions Between 2014 and 2019, the proportion of children carrying serotype 23A increased significantly, while the carriage rate of NTHi decreased. Continuous surveillance is needed to assess the long-term effects of the PCVs on carriage dynamics of pneumococcus and NTHi.

Nosocomial transmission of COVID-19 among immunocompromised hosts can have a serious impact on COVID-19 severity, underlying disease progression and SARS-CoV-2 transmission to other patients and healthcare workers within hospitals. We experienced a nosocomial outbreak of COVID-19 in the setting of a daycare unit for paediatric and young adult cancer patients. Between 9 and 18 November 2020, 473 individuals (181 patients, 247 caregivers/siblings and 45 staff members) were exposed to the index case, who was a nursing staff. Among them, three patients and four caregivers were infected. Two 5-year-old cancer patients with COVID-19 were not severely ill, but a 25-year-old cancer patient showed prolonged shedding of SARS-CoV-2 RNA for at least 12 weeks, which probably infected his mother at home approximately 7–8 weeks after the initial diagnosis. Except for this case, no secondary transmission was observed from the confirmed cases in either the hospital or the community. To conclude, in the day care setting of immunocompromised children and young adults, the rate of in-hospital transmission of SARS-CoV-2 was 1.6% when applying the stringent policy of infection prevention and control, including universal mask application and rapid and extensive contact investigation. Severely immunocompromised children/young adults with COVID-19 would have to be carefully managed after the mandatory isolation period while keeping the possibility of prolonged shedding of live virus in mind.

Parainfluenza virus type 3 (PIV3) and respiratory syncytial virus (RSV) B epidemics occurred in South Korea in late 2021. We investigated epidemiological changes of PIV3 and RSV B infections in Korean children before and during the coronavirus disease 2019 (COVID-19) pandemic.In this multicenter retrospective study, we enrolled patients aged less than 19 years with PIV3 or RSV infection in four university hospitals from January 2018 to January 2022. Demographic and clinical data were extracted from the subject's medical records and analyzed for each virus.A total of 652 children with PIV3 were identified including three epidemics: 216 in 2018, 260 in 2019, and 167 in 2021. Among 627 RSV B cases, 169 were identified in 2017/2018, 274 in 2019/2020, and 115 in 2021/2022. The peak circulation of PIV3 and RSV B epidemics were delayed by 6 and 2 months, respectively, in 2021, compared with those in the pre-COVID-19 period. The median age of PIV3 infections increased in 2021 (21.5 months in 2021 vs. 13.0-14.0 in 2018-2019;We observed changes in the epidemiology and clinical presentation of PIV3 and RSV B infections in Korean children during the COVID-19 pandemic.

The risk of severe outcomes with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta variant remains low in children and adolescents, but less is known about its effect on the SARS-CoV-2-naïve population. This study evaluated clinical manifestations and risk factors for moderate-to-critical coronavirus disease 2019 (COVID-19) in mostly SARS-CoV-2-naïve children and adolescents in 2021.This multicenter retrospective study included patients aged 0-18 years who were hospitalized with COVID-19 at 8 referring hospitals in South Korea during the predelta-predominant and delta-predominant periods in 2021. Each case was labeled as either hospitalization with medical needs or for isolation. Severity was categorized as mild, moderate, severe, or critical with regard to pneumonia presence and illness severity.Among 753 cases, most (99.5%) had no prior history of COVID-19 or vaccination against COVID-19. The proportions of hospitalization with medical needs (3.5% vs. 19.7%), moderate illness (0.9% vs. 4.0%), and severe/critical illness (0.8% vs. 5.3%) increased during delta predominance. The risk of moderate-to-critical COVID-19 among hospitalizations with medical needs was higher among patients aged 12-18 years (adjusted odds ratio [aOR], 4.1; 95% confidence interval [CI], 1.5-11.8) and with obesity (aOR, 6.9; 95% CI, 2.4-19.6) but not among patients infected during delta predominance. However, children with obesity experienced more severe COVID-19 during delta predominance (aOR, 6.1; 95% CI, 1.2-29.6).Despite its similar severity among most SARS-CoV-2-naïve children and adolescents, the delta variant may affect COVID-19 severity in those with high-risk underlying medical conditions. Underlying conditions, particularly obesity, may cause severe COVID-19 in children and adolescents, warranting strong consideration for vaccinating high-risk children.

Background : Yersinia pseudotuberculosis is known to cause fever, gastroenteritis, or acute kidney injury (AKI). There have been several Y. pseudotuberculosis infection outbreaks to date associated with ingestion of contaminated food or unsterile water. While this disease was considered to have practically been eradicated with the improvement in public health, we encountered several cases of AKI associated with Yersinia infection. Methods : We retrospectively collected data from medical records of patients with suspected Y. pseudotuberculosis infection who visited Seoul National University Children's Hospital in 2017. Results : There were nine suspected cases of Yersinia infection (six males and three females; age range 2.99-12.18 years). Among them, five cases occurred in May, and seven patients were residing in the metropolitan Seoul area. Three patients had history of drinking mountain water. Every patient first presented with fever for a median of 13 days, followed by gastrointestinal symptoms and oliguria. Imaging studies revealed mesenteric lymphadenitis, terminal ileum wall thickening, and increased renal parenchymal echogenicity. Creatinine levels increased to 5.72 ± 2.18 mg/dL. Urinalysis revealed sterile pyuria, proteinuria, and glycosuria. Oliguria continued for 4 to 17 days, and two patients required dialysis; however, all of them recovered from AKI. Mucocutaneous manifestations developed later. In the diagnostic work-up, Yersinia was isolated from the stool culture in one patient. Anti-Yersinia immunoglobulin (Ig) A and IgG were positive in 6 patients. Conclusion : Y. pseudotuberculosis infection is an infrequent cause of interstitial nephritis presenting with AKI. When a patient presents with fever, gastroenteritis, and AKI not resolving despite hydration, the clinician should suspect Y. pseudotuberculosis infection.

In areas with high prevalence of macrolide-resistant Mycoplasma pneumoniae (MRMP) pneumonia, treatment in children has become challenging. This study aimed to analyze the efficacy of macrolides and doxycycline with regard to the presence of macrolide resistance. We analyzed children with MP pneumonia during the two recent epidemics of 2014–2015 and 2019–2020 from four hospitals in Korea. Nasopharyngeal samples were obtained from children with pneumonia for MP cultures and polymerase chain reaction (PCR). Macrolide resistance was determined by the analysis of 23S rRNA gene transition. Time to defervescence and to chest X-ray improvement were analyzed. Of 145 cases, the median age was 5.0 years and MRMP accounted for 59 (40.7%). Among macrolide-susceptible MP (MSMP), 78 (90.7%) were treated with macrolides and 21 (35.6%) in the MRMP group with doxycycline. In MRMP pneumonia, shorter days to defervescence (2 vs. 5 days, p &lt, 0.001) and to chest X-ray improvement (3 vs. 6 days, p &lt, 0.001) in the doxycycline group than in the macrolide group was observed, whereas no differences were observed among children with MSMP pneumonia. Compared to macrolides, treatment with doxycycline resulted in better outcomes with a shorter time to defervescence and to chest X-ray improvement among children with MRMP pneumonia.

Background: Compared to influenza virus and respiratory syncytial virus, common human coronaviruses (HCoVs) are relatively understudied due to the mild nature of HCoV infection. Given the lack of local epidemiology data on common HCoVs in Korea, we aimed to describe epidemiological characteristics of common HCoVs. Methods: Respiratory viral test results from more than 67,000 respiratory samples from the two data sources, Korea Influenza and Respiratory Viruses Surveillance System (KINRESS, N=58,253) and Seoul National University Children’s Hospital (SNUCH, N=9,589) were analyzed from January 2015 to December 2019. Viral detection was done by the multiplex RT-PCR. Demographics and clinical diagnosis were collected for previously healthy children tested positive for HCoVs in SNUCH. Results: Of the 67,842 samples tested, 1 or more respiratory viruses were detected from 35,459 (52.2%) samples and 2,854 (4.2%) samples were positive for HCoVs (OC43 2.1%, NL63 1.7%, 229E 0.4%). All 3 types were co-circulated during winter months (November to February) with some variation by type. HCoV-OC43 was most prevalent, peaking every winter. HCoV-NL63 circulated with alternate peaks occurring between January-March and November-February. Meanwhile, HCoV-229E had smaller peaks every other winter in 2015/2016 and 2017/2018. From the national surveillance data, HCoV infection was most prevalent among 0 to 1 year old children and older adults aged over 70 years. 18.2% of the HCoV-positive samples were co-detected with other respiratory viruses, with the highest co-detection rate (33.7%) in children 0 to 1 year of age and the lowest co-detection rate (3.6%) in adults ≥70 years old. Upper respiratory tract infection was the most common (60.0%) clinical diagnosis of the 135 previously healthy children. Croup accounted for 17.0% of NL63-positive childrenConclusion: This study described the epidemiological characteristics of 3 types of common HCoVs (OC43, NL63, 229E) in Korea; the highest prevalence of OC43, concurrent circulation during winter, and age difference in HCoV infection and co-detection rate with other respiratory virus. It may be informative to monitor any changes in the epidemiology of common HCoVs as the COVID-19 pandemic continues.

Considering the mild degree of coronavirus disease 2019 (COVID-19) in children and the enormous stress caused by isolation in unfamiliar places, policies requiring mandatory isolation at medical facilities should be reevaluated especially given the impact of the pandemic on the availability of hospital beds. In this study, we assessed the usefulness of facility isolation and the transmissibility of severe acute respiratory syndrome coronavirus 2 by infected children to uninfected caregivers in isolation units at a hospital and a residential treatment center in Seoul during August-November 2020. Fifty-three children were included and median age was 4 years (range, 0–18). All were mildly ill or asymptomatic and isolated for a median duration of 12 days. Thirty percent stayed home longer than 2 days before entering isolation units from symptom onset. Among 15 uninfected caregivers, none became infected when they used facemasks and practiced hand hygiene. The results suggest children with mild COVID-19 may be cared safely at home by a caregiver in conditions with adherence to the preventive measures of wearing facemasks and practicing hand hygiene., Graphical Abstract

Objectives In Korea, the National Immunization Program provided trivalent inactivated influenza vaccines (IIV3) to all children aged 6–59 months during the 2017–2018 season. In this study, we aimed to evaluate the vaccine effectiveness (VE) of IIV3 in children during the 2017–2018 season. Methods Children aged 6–59 months who were tested for influenza for their acute respiratory illness in four hospitals during the 2017–2018 influenza season were included. We estimated the VE of IIV3 by test-negative case-control design based on the rapid influenza diagnostic test (RIDT) or reverse transcription polymerase chain reaction (RT-PCR) test results. Results A total of 4738 children were included in this study. The number of laboratory-confirmed influenza cases was 845 (17.8%), and there were 478 cases of influenza A and 362 cases of influenza B. The adjusted VE based on RT-PCR was 53.4% (95% CI, 25.3–70.5) against any influenza, 68.8% (95% CI, 38.7–84.1) against influenza A, and 29.7% (95% CI, −35.1 to 61.8) for influenza B. The adjusted VE based on RIDT was 14.8% (95% CI, −4.4 to 30.0) against any influenza, 24.2% (95% CI, 3.1–40.2) against influenza A, and −5.1% (95% CI, −42.6 to 21.4) against influenza B. Age-specific VE based on RT-PCR against any influenza was 44.1% (95% CI, −0.2 to 67.8) in children aged 6 months to 2 years and 59.3% (95% CI, 8.8–81.9) in children aged 3– Conclusion Our results suggest moderate protection (53.4%) of IIV3 against RT-PCR laboratory-confirmed influenza in children in the 2017–2018 influenza season. However, the RIDT hampered the validity to assess VE during influenza season. Caution is needed when interpreting an RIDT-based test negative design influenza VE study.

Purpose: Common human coronaviruses (HCoVs) are relatively understudied due to the mild nature of HCoV infection. Given the lack of local epidemiology data on common HCoVs, we aimed to describe clinical and epidemiological characteristics of common HCoVs in children. Methods: Respiratory viral test results from 9,589 respiratory samples from Seoul National University Children's Hospital were analyzed from January 2015 to December 2019. Viral detection was done by the multiplex reverse transcription polymerase chain reaction. Demographics and clinical diagnosis were collected for previously healthy children tested positive for HCoVs. Results: Of the 9,589 samples tested, 1 or more respiratory viruses were detected from 5,017 (52.3%) samples and 463 (4.8%) samples were positive for HCoVs (OC43 2.8%, NL63 1.4%, 229E 0.7%). All 3 types co-circulated during winter months (November to February) with some variation by type. HCoV-OC43 was the most prevalent every winter season. HCoV-NL63 showed alternate peaks in late winter (January to March) and early winter (November to February). HCoV-229E had smaller peaks every other winter. Forty-one percent of HCoV-positive samples were co-detected with additional viruses;human rhinovirus 13.2%, respiratory syncytial virus 13.0%, influenza virus 4.3%. Common clinical diagnosis was upper respiratory tract infection (60.0%) followed by pneumonia (14.8%), croup (8.1%), and bronchiolitis (6.7%). Croup accounted for 17.0% of HCoV-NL63-positive children. Conclusions: This study described clinical and epidemiological characteristics of common HCoVs (OC43, NL63, 229E) in children. Continuing surveillance, perhaps by adding HKU1 in the diagnostic panel can further elucidate the spectrum of common HCoV infections in children. © 2021 The Korean Society of Pediatric Infectious Diseases.

Background The extended-valency pneumococcal conjugate vaccines (PCVs) were implemented into Korean national immunization program in 2014. This study investigated the change in genetic structures of Streptococcus pneumoniae causing invasive pneumococcal disease (IPD) in Korean children after 10- and 13-valent conjugate vaccine (PCV10 and PCV13, respectively) use. Methods Between January 2014 and December 2016, invasive isolates were collected from 23 hospitals throughout Korea. Cases of IPD were defined by isolating pneumococci from normally sterile sites. Each pneumococcal isolate was identified using standard microbiological techniques and serotyped by Quellung reaction. The multi-locus sequence typing (MLST) was analyzed for randomly selected isolates. Results A total of 91 pneumococcal isolates were analyzed. Common serotypes were 10A (18.7%), 12F (11.0%), 15A (9.9%), 19A (9.9%), 15B/C (7.7%), 23A (6.6%), 35B (5.5%), and 23B (4.4%). The isolates belonged to 38 sequence types (STs), including 4 newly discovered STs. Of the 4 clonal complexes (CCs), 3 clonal complexes were antibiotic-resistant international clones. CC166 (11.9%) were associated with non-vaccine serotypes (NVTs; 11A, 15B/C, 23A, and 13). Serotypes of CC320 (10.9%) comprised of serotype 19A and 19F. The main serotypes responsible for CC81 (10.9%) were serogroup 15. New serotype-ST combinations were observed, especially in serotype 13 and serogroup 15. Also, a possibility of capsular switch event was noted between serogroup 6 and serogroup 15A.). Conclusion The introduction of extended-valency PCVs has resulted in the change of the genetic structure of pneumococcal isolates in Korean children. This study demonstrates that selective pressure from PCV10/13 caused predominant serotypes to be NVTs and genetic changes such as capsular switch events. Disclosures All authors: No reported disclosures.

Eikenella corrodens는 구강 상재균으로 두경부 감염을 주로 일으키나 면역력이 정상인 소아청소년에게 감염을 일으키는 경우는 흔하지 않다. 저자들은 발열, 두통, 구토를 증상으로 입원한 이전까지 건강하였던 13세 남자에게서 E. corrodens 감염에 의한 중추신경계 경막 외 농양을 진단하여 보고하는 바이다. 초기에 시행한 신체검진에서 경부 강직은 없었으나, 우측 이루가 관찰되었다. 뇌 magnetic resonance imaging (MRI) 영상소견에서 4.5 cm 크기의 경막 외 농양이 우측 측두엽 부근에서 발견되었고, 양측 사골동염 및 접형동염, 우측 유양돌기염과 중이염이 동반되었다. Vancomycin과 cefotaxime 투약 중에도, 임상증상이 호전되지 않고 추적 MRI에서 경막 외 농양의 크기가 증가하고, 우측 접형동에 농양이 형성되어 항균요법과 함께 천두술과 내시경적 접형동 절개술을 시행하였다. 수술 시 경막 외 농양과 접형동에서 악취가 나는 고름이 다량 흡인되었으며 두 부위에서 흡인된 검체 모두에서 E. corrodens가 배양되었다. 수술 이후 3주 동안 cefotaxime 정맥주사로 치료받고 합병증 없이 회복하였다. 결론적으로, E. corrodens는 건강한 소아청소년에서 치료되지 않은 세균성 부비동염에 합병하여 중추신경계 농양의 원인이 될 수 있다.

This subject investigated visual evaluation of preference and fitness level of set-in sleeve in sleeve types(form)and studied suitable sleeve type at silhouette and targeted female students in twenties. The results of study were as follows: 1. Visual evaluation factors in set-in sleeve of sleeve types were selected 6 factors; the 1st factor is decorativeness, the 2nd factor is attractiveness, the 3rd factor was activeness, the 4th factor was feminine, the 5th factor was charming and 6th factor was a figural element. Decorativeness and attractiveness factors in visual evaluation of sleeve types were the most important level. 2. The visual evaluation differences of sleeve types in set-in sleeve were as follows; in the 1st factor, S and P2 were the most decorative sleeve type. in the 2nd factor, S, P2 and P3 are the most attractive sleeve type. in the 3rd factor, B and P3 were the most active sleeve type. in the 4th factor, L was the most feminine sleeve type. in the 5th factor, P1, L and P3 were charming sleeve type. in the 6th factor, P3 was evaluated that it shows narrowened shoulder sleeve types. 3. The analysis result of preference and wearing level in each sleeve types were as follows. 20's female university students like to wear S, P1, P2 and P3 sleeve types and the most favorite sleeve types are S, P2 and P3. 4. The analysis result of silhouette set-in sleeve in sleeve types; S, B and P2 in H-type silhouette, P2, S and P1 in A-type silhouette, B and P3 in O-type silhouette, L and P3 in X-types silhouette were show the most suitable sleeve types.

We propose an ad-hoc multicast routing protocol, referred to as PatchODMRP. PatchODMRP extends the ODMRP (on-demand multicast routing protocol), which is a mesh-based multicast routing protocol proposed for ad-hoc networks. In ODMRP, the nodes that are on the shortest paths between the multicast group members are selected as forwarding group (FG) nodes, and form a forwarding mesh for the multicast group. The ODMRP reconfigures the forwarding mesh periodically to adapt it to the node movements. When the number of sources in the multicast group is small, usually the forwarding mesh is formed sparsely and it can be very vulnerable to mobility. In this case, very frequent mesh reconfigurations are required in ODMRP, resulting in a large control overhead. To deal with this problem in a more efficient way, PatchODMRP deploys a local patching scheme instead of having very frequent mesh reconfigurations. In PatchODMRP, each FG node keeps checking if there is a symptom of mesh separation around itself. When an FG node finds such a symptom, it tries to patch itself to the mesh with local flooding of control messages. Through a course of simulation experiments, the performance of PatchODMRP is compared to the performance of ODMRP. The simulation results show that PatchODMRP improves the data delivery ratio, and reduces the control overheads. It has also been shown that the performance gain is larger when the degree of node mobility is bigger.