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(1) Background: The aim of this study was to evaluate the prevalence of obesity and metabolic syndrome since the COVID-19 pandemic outbreak utilizing representative data on youth aged 2–18 years from the Korean National Health and Nutrition Examination Surveys (KNHANES) conducted in 2019–2020. (2) Methods: The survey consists of three parts: health interviews, health examinations, and nutrition surveys. From the 2019 and 2020 surveys, 1371 (2–9 years = 702 and 10–18 years = 669) and 1124 (2–9 years = 543 and 10–18 years = 581) individuals were included in the analysis. (3) Results: The mean body mass index (BMI) increased significantly among youth aged 2–9 years from 16.53 kg/m2 in 2019 to 17.1 kg/m2 in 2020 (p < 0.01). In youth aged 10–18 years, the BMI was found to increase slightly from 21.25 kg/m2 in 2019 to 21.41 kg/m2 in 2020 (p = 0.64). The increasing prevalence of extreme obesity was significant in girls, especially those aged 2–9 years (p < 0.01). However, extreme obesity had increased in 10–18-year-old boys (p = 0.08). The overall prevalence of metabolic syndrome in adolescents increased from 3.79% to 7.79% during the COVID-19 pandemic (p = 0.01). (4) Conclusions: We observed that the prevalence of obesity and metabolic syndrome among children and adolescents has increased after the COVID-19 outbreak. This is believed to be associated with an increase in the rate of early comorbidities in adulthood. The prevention of the progression of pediatric obesity has recently become an urgent public health concern in Korea.

Purpose: Pediatric diabetes is a common health burden worldwide. This study aimed to investigate the prevalence of fasting hyperglycemia in Korean youth aged 10–18 years and to evaluate its association with metabolic indicators.Methods: To assess the risk of diabetes in domestic children and adolescents, the prevalence of fasting hyperglycemia was calculated, a trend was evaluated using multi-year Korea National Health and Nutrition Examination Survey (KNHANES) data, and multivariate analysis was performed to evaluate the relationships between hyperglycemia and metabolic factors.Results: The prevalence of fasting hyperglycemia, defined as impaired fasting glucose (fasting glucose level > 100 mg/dL and < 125 mg/dL), or diabetes mellitus (fasting glucose ≥ 126 mg/dL) was estimated in Korean teenagers. The prevalence increased from the fourth (2007–2009) to the fifth (2010–2012), sixth (2013–2015), and seventh (2016–2018) KNHANES surveys, from 5.39 to 4.79, 10.03, and 11.66 per 100 persons, respectively. In multivariate analysis, systolic blood pressure and serum triglycerides were higher in the fasting hyperglycemia group; systolic blood pressures were 109.83 mmHg and 112.64 mmHg and serum triglycerides were 81.59 mg/dL and 89.60 mg/dL in the normal blood glucose and fasting hyperglycemia groups, respectively.Conclusion: The prevalence of fasting hyperglycemia among children and adolescents has increased over the past decade, and this increase is potentially associated with metabolic abnormalities such as hypertension and hypertriglyceridemia. Effort is urgently required to reduce this chronic medical burden in adolescence.

Background: Kawasaki disease (KD) is an acute febrile vascular disease of unknown cause that affects the whole body. KD typically occurs in infants under the age of five and is found mainly in East Asian countries. Few studies have reported on the relationship between the pollutant PM2.5 and KD, and the evidence remains irrelevant or insufficient. Objectives: We investigated the relationship between short-term exposure to PM2.5 and KD hospitalizations using data from Ewha Womans University Mokdong Hospital, 2006 to 2016. Methods: We obtained data from the hospital EMR (electronic medical records) system. We evaluated the relationship between short-term exposure to PM2.5 and KD hospitalizations using a case-crossover design. We considered exposures to PM2.5 two weeks before the date of KD hospitalization. We analyzed the data using a conditional logistic regression adjusted for temperature and humidity. The effect size was calculated as a 10 &mu, g/m3 increase in PM2.5 concentration. We performed a subgroup analysis by sex, season, age group, and region. In the two-pollutants model, we adjusted SO2, NO2, CO, and O3, but the effect size did not change. Results: A total of 771 KD cases were included in this study. We did not find any statistically significant relationship between PM2.5 and children&rsquo, s KD hospitalization (two-day moving average: odds ratio (OR) = 1.01, 95% confidence intervals (CI) = 0.95, 1.06, seven-day moving average: OR = 0.98, CI = 0.91, 1.06, 14-day moving average: OR = 0.93, CI = 0.82, 1.05). A subgroup analysis and two pollutant analysis also found no significant results. Conclusion: We did not find a statistically significant relationship between PM2.5 and children&rsquo, s KD hospitalizations. More research is needed to clarify the association between air pollution, including PM2.5, and KD.

Background: Kawasaki disease (KD) is an acute febrile vascular disease of unknown cause that affects the whole body. KD typically occurs in infants under the age of five and is found mainly in East Asian countries. Few studies have reported on the relationship between the pollutant PM2.5 and KD, and the evidence remains irrelevant or insufficient. Objectives: We investigated the relationship between short-term exposure to PM2.5 and KD hospitalizations using data from Ewha Womans University Mokdong Hospital, 2006 to 2016. Methods: We obtained data from the hospital EMR (electronic medical records) system. We evaluated the relationship between short-term exposure to PM2.5 and KD hospitalizations using a case-crossover design. We considered exposures to PM2.5 two weeks before the date of KD hospitalization. We analyzed the data using a conditional logistic regression adjusted for temperature and humidity. The effect size was calculated as a 10 μg/m3 increase in PM2.5 concentration. We performed a subgroup analysis by sex, season, age group, and region. In the two-pollutants model, we adjusted SO2, NO2, CO, and O3, but the effect size did not change. Results: A total of 771 KD cases were included in this study. We did not find any statistically significant relationship between PM2.5 and children’s KD hospitalization (two-day moving average: odds ratio (OR) = 1.01, 95% confidence intervals (CI) = 0.95, 1.06; seven-day moving average: OR = 0.98, CI = 0.91, 1.06; 14-day moving average: OR = 0.93, CI = 0.82, 1.05). A subgroup analysis and two pollutant analysis also found no significant results. Conclusion: We did not find a statistically significant relationship between PM2.5 and children’s KD hospitalizations. More research is needed to clarify the association between air pollution, including PM2.5, and KD.

Background Prenatal exposure to bisphenol A (BPA) and phthalates could trigger immune response. Few studies have investigated the association between prenatal BPA and phthalate exposure and atopic dermatitis (AD) in infants. Objective We aimed to clarify the joint association of prenatal exposure to BPA and phthalate metabolites with AD incidence in 6-month-old infants. Methods We included 413 mother-child pairs from the Mothers and Children's Environmental Health (MOCEH) in a prospective birth cohort study. Maternal urinary BPA, mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and mono-n-butyl phthalate (MnBP) concentrations were measured during early and late pregnancy. We applied the Bayesian kernel machine regression (BKMR) with probit regression to estimate the association of BPA and phthalate metabolites with AD incidence after adjusting for potential confounders. Individual association was estimated by differences in predicted probabilities comparing each individual chemical concentration at 75th versus 25th percentiles, while other chemicals were set at their median. Overall joint effect was estimated by differences in predicted probabilities comparing all chemical concentrations at 75th versus 25th percentiles. Results Individual effect of MEHHP in late pregnancy was strongly associated with incident AD [Difference: 0.244 (95% credible interval: −0.066, 0.554)] in the model including both early and late exposures. Furthermore, we confirmed overall joint association of urinary BPA and phthalate metabolites during pregnancy with a higher risk of AD [0.347 (0.168, 0.526) for late pregnancy exposure, and 0.307 (0.094, 0.521) for both early and late pregnancy]. Additionally, the joint association was more prominent among girls than that in boys. Conclusions The joint association of prenatal exposure to BPA and phthalates could be associated with the incident AD in 6-month-old infants. Further studies are needed to confirm the synergistic effect of BPA and phthalate exposures on AD in children.

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been recommended for adults aged ≥65years. To evaluate functional immune response against the additional 11 serotypes that are included in PPSV23, but not the 13-valent pneumococcal conjugate vaccine (PCV13), serotype-specific anti-pneumococcal antibodies were examined using an opsonophagocytic assay (OPA).Participants ≥65years of age that were naïve to the pneumococcal vaccine were enrolled. They were divided into two groups according to their age: group 1 (N=30; aged 65-74years) and group 2 (N=32; aged ≥75years). The functional antibody response prior to and 4weeks post-immunization with PPSV23 was determined, using a multiplexed OPA (MOPA) for 11 pneumococcal serotypes (2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F).Geometric mean OPA titers (GMTs) to 11 serotypes were significantly increased in both groups post-immunization compared to those prior to immunization. The GMTs for all serotypes were not significantly different between the two groups after immunization. The proportion of subjects with OPA titers post-immunization of ≥8 and ≥64 was 93-100% and 80-100% for the 11 serotypes, respectively, while subjects with a ≥4-fold increase in OPA titers ranged from 9 to 90% for the 11 serotypes.This study revealed that PPSV23 vaccination induced significant functional immune responses to 11 non-PCV13 serotypes in older adults. The MOPA has been shown to be a useful tool for future application in evaluating new PCVs in older adults. The clinical trial registration number is KCT 0001963 (CRIS, https://cris.nih.go.kr/cris/en/).

Group B streptococcus (GBS) infection is a leading cause of sepsis and meningitis among infants, and is associated with high rates of morbidity and mortality in many countries. Protection against GBS typically involves antibody-mediated opsonization by phagocytes and complement components. The present study evaluated serotype-specific functional antibodies to GBS among Korean infants and in intravenous immunoglobulin (IVIG) products. An opsonophagocytic killing assay (OPA) was used to calculate the opsonization indices (OIs) of functional antibodies to serotypes Ia, Ib, and III in 19 IVIG products from 5 international manufacturers and among 98 Korean infants (age: 0-11 months). The GBS Ia, Ib, and III serotypes were selected because they are included in a trivalent GBS vaccine formulation that is being developed. The OI values for the IVIG products were 635-5,706 (serotype Ia), 488-1,421 (serotype Ib), and 962-3,315 (serotype III), and none of the IVIG lots exhibited undetectable OI values (< 4). The geometric mean OI values were similar for all 3 serotypes when we compared the Korean manufacturers. The seropositive rate among infants was significantly lower for serotype Ia (18.4%), compared to serotype Ib and serotype III (both, 38.8%). Infant age of ≥ 3 months was positively correlated with the seropositive rates for each serotype. Therefore, only a limited proportion of infants exhibited protective immunity against serotype Ia, Ib, and III GBS infections. IVIG products that exhibit high antibody titers may be a useful therapeutic or preventive measure for infants. Further studies are needed to evaluate additional serotypes and age groups.

Background After the introduction of the meningococcal ACWY-CRM197 conjugate vaccine (MenACWY-CRM) in 2012 and the meningococcal ACWY-diphtheria toxoid conjugate vaccine (MenACWY-DT) in 2014, immunization was recommended for certain high-risk groups including new military recruits in Korea. However, comparative immunogenicity studies for these vaccines have not been performed in Korea. Here, we compared the immunogenicity of these two vaccines in healthy adults. Methods A total of 64 adults, 20–49 years of age, were randomly divided into two groups (1:1) to receive either of the two vaccines. The sera were obtained before and 1 month after vaccination and tested for serogroup-specific serum bactericidal activity using baby rabbit complement. Results There were no significant differences post-vaccination in the geometric mean indices and the seropositive rate to all serogroups between the vaccines. The proportion of seropositive subjects after vaccination ranged from 88% to 100%. Conclusion Both meningococcal conjugate vaccines showed good immunogenicity in healthy Korean adults without statistically significant differences. Further investigations for serotype distribution of circulating meningococci and the immune interference between other diphtheria toxin-containing vaccines concomitantly used for military recruits are needed to optimize immunization policies. Trial Registration Clinical Research Information Service Identifier: KCT0002460, Graphical Abstract

목적: Streptococcus agalactiae (group B streptococcus [GBS])은 신생아, 임산부 및 성인에서 침습성 감염의 주요 원인균이다. 면역체계가 손상되거나 약화된 경우, 잘 알려진 10개의 GBS 혈청형 중 흔하지 않은 IV, VI-IX에 의해 침습적인 질환이 발생할 수 있다. 그러나, 지금까지 사람의 혈청 및 정주용 면역글로불린(intravenous immunoglobulin, IVIG) 제제 중 GBS의 흔하지 않은 혈청형에 대한 옵소닌 항체(opsonophagocytic antibody) 활동은 연구되지 않았다. 면역글로불린 치료 요법은 일차 항체 결핍증(primary antibody deficiency, PAD) 환자의 침습적 감염을 치료하거나 예방하는 데 사용된다. 이 연구에서는 면역글로불린에서 GBS에 대한 옵소닌 항체 활성을 평가하고자 한다. 방법: 2015-2016년 국내 두 회사에서 사용가능한 16개 면역글로불린에 대하여 7개 GBS 혈청형 (II 및 IV-IX)에 대한 옵소닌 항체 활성도(opsonic index [OI])를 HL-60 세포와 아기토끼 보체를 사용하여 옵소닌 분석법(opsonophagocytic assay)을 통해 분석하였다. (UAB GBS OPA, http://www.vaccine.uab.edu). 결과: 모든 면역글로불린 제제에서 GBS에 대한 OI의 검출 한계점(≥4)을 초과하였다. 혈청형 VII의 경우, OI 값은 6-136으로 모든 혈청형 중에서 가장 낮았다. IVIG의 최저 수준(trough level)을 추정해볼 때, 일반적인 면역글로불린 용량 (400 mg/kg)은 PAD 환자에게 침습성 GBS 감염을 예방하기 위한 적합한 용량으로 보인다. 결론: 국내에서 사용중인 면역글로불린 제품은 GBS에 대한 높은 수준의 옵소닌 항체 활성을 나타냈다. 면역글로불린은 PAD 환자에게 유용한 치료 또는 예방조치가 될 수 있을 것으로 보인다.

Background Invasive Streptococcus agalactiae (group B streptococcus, GBS) infection most commonly occurs in infants; however, cases of GBS infection in adults, particularly in the elderly with significant underlying diseases, are being increasingly reported. We analyzed the serotype specific opsonophagocytic antibodies (the major mechanism of protection against GBS) in infants, adults, and the elderly. Methods The opsonization indices (OIs) of antibodies against serotype Ia, Ib, II, III, and V GBS were studied in 89 infants, 35 adults (age, 30-50 years), and 62 elderly individuals (age, 65-85 years) according to the University of Alabama at Birmingham GBS opsonophagocytic killing assay protocol (www.vaccine.uab.edu). Results In infants, adults, and elderly groups respectively, geometric mean of OI against GBS serotype Ia were 3, 7, and 32; against GBS serotype Ib were 7, 242, and 252; against serotype II were 93, 363, and 676; against serotype III were 8, 212, and 609; and against serotype V were 4, 639, and 610. The seropositive rate (% of subjects with OI ≥ 4) increased significantly in older age group for all five serotypes. Conclusion During infancy, only a limited proportion of infants have functional immunity against serotype Ia, Ib, II, III, and V GBS. Furthermore, a lack of opsonic activities against GBS observed in some adults and the elderly might predispose such individuals to the risk of invasive GBS infection. Epidemiological monitoring and development of suitable vaccine for these populations are needed.

Background Various pneumococcal vaccines have been evaluated for immunogenicity by opsonophagocytic assay (OPA). A multiplexed OPA (MOPA) for 13 pneumococcal serotypes was developed by Nahm and Burton, and expanded to 26 serotypes in 2012. The development of new conjugate vaccines with increased valence has necessitated expanded MOPAs to include these additional serotypes. In this study, we validated this expanded MOPA platform and applied to measure antibodies against 11 additional serotypes (2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F) in human sera. Methods All materials, including serum, complement, bacterial master stocks, and HL-60 cells, were evaluated for assay optimization. Following optimization, the assay was validated for accuracy, specificity, and intra- and inter-assay precision with sera from adult donors following standard protocols. The assay was applied to evaluate functional antibodies of 42 sera immunized with 23-valent pneumococcal polysaccharide vaccine (PPV23). Results The expanded MOPA platform was specific for all serotypes, with the exception of serotype 20. The assay results were highly correlated with those obtained from single-serotype OPA, indicating acceptable accuracy. The coefficients of variation were 7%–24% and 13%–39% in tests of intra- and inter-assay precision, respectively, using three quality-control samples. A MOPA that included 11 additional serotypes in the PPV23 was established and validated with respect to accuracy, specificity, and precision. The opsonic indices of immune sera were obtained using this validated assay. Conclusion The expanded MOPA will be useful for evaluation of the immunogenicity of PPV23 and future conjugate vaccine formulations., Graphical Abstract

Background There are a number of complications that can occur if there is under-nutrition during pregnancy followed by a period of rapid catch-up growth, including a higher chance of adult obesity, insulin resistance and hypertriglyceridemia. The purposes of this study were to investigate the effects of fetal under-nutrition during late pregnancy and lactation on blood pressure, visceral fat tissue, gene expressions and to evaluate changes after amlodipine- losartan combination treatment. Methods The rats were divided into three groups: the control (C) group, the food restriction (FR: 50 % food restricted diet) group, and the CX group, which was treated with Cozaar XQ (amlodipine- losartan combination drug) in FR rats from postnatal 4 to 20 weeks. Masson’s trichrome staining was performed in the heart tissues. The amount of abdominal visceral fat tissues was measured. Western blot analysis such as angiotensin converting enzyme (ACE), angiotensin II receptor type IA (ATIA), troponin I (Tn I) and endothelial nitric oxide synthase (eNOS) were performed. Results Body weights were significantly higher in the FR group compared with the C group at weeks 8 and 20 and lower in the CX group at week 20. Blood pressure was significantly higher in the FR group compared with the C group at week 20 and lower in the CX group at weeks 12 and 20. The amount of abdominal visceral fat was significantly higher in the FR group compared with the C group at weeks 8, 12 and 20 and significantly lower in the CX group at weeks 16 and 20. Protein expression of ATIA and eNOS were significantly reduced in the CX group at weeks 16 and 20. ACE was significantly reduced in the CX group at week 20 and Tn I was significantly reduced in the CX group at week 16. Conclusions When there is fetal under-nutrition during pregnancy, it leads to obesity, high blood pressure, hypertriglyceridemia and several gene changes in offspring. Amlodipine-losartan combination treatment was able to lower obesity, hypertension, hypertriglyceridemia and several gene changes in rats suffering from fetal under-nutrition during pregnancy.

Background The quadrivalent meningococcal conjugate vaccines do not target serogroup B meningococcus (MenB), an important cause of meningitis and sepsis. MenB vaccines have been recently developed and licensed for infants and young adults. Serum bactericidal activity serves as an immunological index for evaluating the immunogenicity of vaccines. However, there is no standardized serum bactericidal assay (SBA) for MenB owing to difficulty in selecting target strains and complement sources. Using fetal bovine serum, we developed a new SBA by modifying a previous SBA for meningococcal serogroups A, C, W135, and Y and applied it to clinical samples. Methods An isolate from an invasive disease and three reference strains were used as the target strains, and the genotypes of the antigens contained in the MenB vaccine (4CMenB) (Bexsero; GlaxoSmithKline) were determined. Non-specific killing was assessed by using baby rabbit serum, fetal bovine serum, and healthy adult serum as complement sources. Serum was obtained from clinical samples of six healthy adults before and 1 month after 4CMenB immunization. Results The isolate and the three reference strains all contained factor H binding protein (fHBP) peptide type 1.1, which was consistent with the fHBP antigens contained in 4CMenB. The bactericidal activity in the serum (complement source) of 30 healthy adults ranged from 53% to 90%. Non-specific killing in baby rabbit serum was greater than 80%. Considering the species specificity of meningococcal fHBP, non-specific killing (82% - 91%) was similar when human factor H was added. Non-specific killing was less than 50% in fetal bovine serum, which was used as the complement source for evaluation of clinical samples. After 4CMenB immunization, the serum bactericidal indices for all the test sera were increased 4 times or more. Conclusion We identified fetal bovine serum as a potential complement source for the MenB SBA assay. This method should be standardization using reference sera, and the putative protective SBA indices for fetal bovine serum should be determined. Disclosures All authors: No reported disclosures.

목적: 뎅기바이러스 감염 환자 발생은 해외 여행이 증가함에 따라 증가하고 있다. 최근 감염 경험이 없는 사람에게 백신을 접종하면 이후 야생 뎅기바이러스 감염 시 중증 뎅기열 증상을 보일 수 있다고 연구된 바 있다. 따라서, 본 연구는 한국의 다양한 연령군에서 뎅기바이러스에 대한 혈청역학을 연구하였다. 방법: 건강한 영아 98명(2개월-1세), 청소년 152명(13-19세), 성인 90명(20-50세) 및 노인 106명(65세 이상)에서 수집한 혈청 총 446명을 대상으로 하였다. 각 연령군의 뎅기바이러스 immunoglobulin G (IgG) 항체 검사를 ELISA을 통해 측정하였다. 또한 뎅기바이러스 IgG 항체 검사에서 양성 또는 equivocal을 보이는 혈청에 한하여 일본뇌염 바이러스의 IgG 항체를 검사하였다. 결과: 총 446명 검체 중, 청소년군에서 1명(0.2%)만 뎅기바이러스 항체 검사에서 양성으로 나왔다. Equivocal은 14명(3.1%)으로, 청소년군 10명과 노인군 4명이 해당하였다. 뎅기바이러스 IgG 양성이 나온 1명에서 일본뇌염 바이러스 또한 IgG 양성으로 나왔다. 뎅기바이러스 IgG equivocal이 나온 14명에서는 일본뇌염 바이러스 IgG 양성이 6명, equivocal이 3명이었고 음성은 5명이었다. 결론: 한국인에서 뎅기바이러스에 대한 항체 보유율은 매우 낮았다. 본 연구는 향후 뎅기열 예방을 위한 보건 정책 수립에 중요한 자료가 될 수 있을 것이며 향후 지속적인 혈청면역 평가도 필요할 것이다.

목적: 1995년 한국에서 b형 헤모필루스 인플루엔자(Haemophilus influenzae type b [Hib]) 백신이 도입된 이후, 2013년 국가예방접종에 포함되었다. Hib 백신 도입 시기 이후 다른 나라의 일부 연구에 따르면, 침습적 Hib 질환은 소아보다 성인, 특히 노인 및 면역 저하 환자에서 더 자주 발생한다고 보고하였다. 따라서, 본 연구는 20-85세의 한국 성인에서 항-polyribosylribitol phosphate (PRP) 항체의 양적 및 질적 측정을 통하여 질병 감수성을 평가하고자 하였다. 방법: 혈청은 39명의 건강한 성인(20-50세)과 면역 저하 상태가 아닌 30명의 노인(75-85세)에서 수집하였다. 모든 피험자는 7일 이내에 항생제를 복용하지 않았다. 항-PRP 면역글로불린 G (immu-noglobulin G [IgG]) 항체가 및 혈청 살상능 역가(serum bactericidal index [SBI])는 효소결합면역흡착측정법과 혈청 살상능 평가분석을 통해 측정하였다. 결과: 항-PRP IgG 항체가의 기하평균 및 SBI의 기하평균은 성인군에서 각각 0.88 μg/mL (95% 신뢰구간, 0.17-3.85) 및 354 (95% 신뢰구간, 50-2,499)이었고, 노인군에서는 각각 1.67 μg/mL (95% 신뢰구간, 0.53-5.24) 및 449 (95% 신뢰구간, 146-1,376)이었다. 소아에서 Hib 감염에 대한 방어 농도로 인정하고 있는 0.15 및 1.0 μg/mL을 적용하였을 때, 항체 양성률은 성인군에서 87.2%, 노인군에서 100%였다. SBI의 양성률(SBI ≥4)은 성인군에서 82.1%, 노인군에서 100%였다. 결론: 대부분의 성인군과 노인군에서 양적으로나 기능적으로 Hib 질환에 대한 방어 면역력을 가지고 있었으나 모두는 아니었다. 높은 면역력과 낮은 Hib 순환율은 인구에서 Hib에 대한 자연면역을 감소시킬 수 있으므로, Hib 면역과 질병에 대한 지속적인 감시가 필요하다.