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National cohort data collected during the coronavirus disease 2019 (COVID-19) delta and omicron periods in Korea revealed a lower risk of severe infection in recipients of three doses of the COVID-19 vaccine (adjusted odds ratio [aOR], 0.05–0.08). The risk of death was reduced during the omicron period compared to the delta period (aOR, 0.75; 95% confidence interval, 0.67–0.84).
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As of September 3, 2022, 5,388,338 coronavirus disease 2019 (COVID-19) cases and 46 deaths (3 in 2021 and 43 in 2022) were reported in children ≤ 18 years in Korea. Cumulative confirmed cases accounted for 67.3% of the population aged ≤ 18 years and case fatality rate was 0.85/100,000. Among 46 fatal cases, 58.7% were male and median age was 7 years.Underlying diseases were present in 47.8%; neurologic diseases (63.6%) and malignancy (13.6%) most common. Only four had history of COVID-19 immunization. COVID-19 associated deaths occurred at median 2 days from diagnosis (range: −1 to 21). Among COVID-19 deaths, 41.3% occurred before admission; 2 before hospital arrival and 17 in the emergency department. Among children whose cause was documented, myocarditis, respiratory and multiorgan failure were most common. COVID-19 associated death was seen early after diagnosis in children and public health policies to provide access to medical care for children with COVID-19 are essential during the pandemic.
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In mid-2022, as the wave of pediatric coronavirus disease 2019 (COVID-19) cases escalated in South Korea, a public-private partnership was made to establish a Pediatric COVID-19 Module Clinic (PMC). We describe the utilization of the first prototype children’s modular clinic in Korea University Anam Hospital functioning as the COVID-19 PMC. Between August 1 and September 30, 2022, a total of 766 children visited COVID-19 PMC. Daily number of patient visits to the COVID-19 PMC ranged between 10 and 47 in August; and less than 13 patients per day in September 2022. Not only the model provided timely care for the COVID-19 pediatric patients, but it also enabled safe and efficacious care for the non-COVID-19 patients in the main hospital building while minimizing exposure risk to severe acute respiratory syndrome coronavirus 2 transmission. Current description highlights the importance of spatial measures for mitigating in-hospital transmission of COVID-19, in specifically on pediatric care.
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Kikuchi-Fujimoto disease (KFD) is an acute febrile disease that mainly involves histiocytic necrotizing lymphadenitis in children and young adults. Diagnosis of KFD is even more difficult if image-guided percutaneous biopsy is technically challenging. We present a case of clinically diagnosed KFD in an 11-year-old boy who presented with fever, abdominal pain, and mesenteric lymphadenopathy, resulting in a diagnostic challenge. Additionally, we conducted a systematic review, and our goal was to describe the spectrum of disease, therapy, and outcomes. We identified 15 cases of KFD with symptoms that mimicked mesenteric lymphadenitis. Reports from the Americas, Europe, and Asia were also included. Most patients were male, exhibited leukopenia and elevated inflammatory markers, and recovered without significant sequelae or complications. A high index of suspicion of KFD should be maintained in children presenting with prolonged fever and unusual manifestations, such as mesenteric lymphadenitis.
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This was a cross-sectional study using the data collected from a nationwide survey between November and December 2022 to explore factors associated with hesitancy towards coronavirus disease 2019 (COVID-19) vaccination for children. Among 3,011 participants with child aged 5–11 years, 82.5% demonstrated hesitancy towards vaccinating their child. This was more common among mothers (odds ratio 1.84 [95% confidence interval 1.46–2.31]), those residing outside metropolitan area (urban: 2.46 [1.89–3.20]; rural: 2.87 [2.09–3.93]) or with history of COVID-19 diagnosis (2.22 [1.78–2.76]). Parents were also hesitant if their child recently had COVID-19 (3.41 [2.67–4.37]). Conversely, they were less likely to be hesitant if they had three or more children (0.66 [0.46–0.94]) or if their child has underlying medical condition(s) (0.54 [0.41–0.71]). Our findings highlight high prevalence of parental hesitancy towards COVID-19 vaccination for children, and call for targeted outreach efforts from the stakeholders to facilitate the vaccine uptake in this pediatric population.
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Background@#We aimed to assess the risk of maternal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and early abortive outcomes after the association between coronavirus disease 2019 (COVID-19) vaccination during the preconceptional period and preclinical pregnancy, which are likely to be inadvertent vaccination. @*Methods@#We used data from the Korea Disease Control and Prevention Agency-COVID19-National Health Insurance Service cohort from December 2020 to December 2021. The vaccinated pregnant women were matched to unvaccinated pregnant controls at a 1:4 ratio.The risks of SARS-CoV-2 infection and intensive care unit (ICU) admission within 14 days of infection were analyzed to assess its effectiveness. For safety measures, the adjusted relative risks (aRRs) of early abortive outcomes for the first COVID-19 vaccination during the preconceptional and preclinical periods were calculated considering covariates. We compared the risk of early abortion between mRNA and viral vector vaccines. @*Results@#The overall COVID-19 vaccination rates during the preconceptional period and preclinical pregnancy were 3.1% (6,662/215,211) and 2.6% (5,702/215,211), respectively.The cumulative incidence of ICU admission within 14 days of SARS-CoV-2 infection was 6/100,000 in the unvaccinated group, whereas there were no ICU admissions in the vaccinated groups. The risks of early abortive outcomes were not significantly different between the preconceptional vaccination group and the unvaccinated group (aRR, 1.04; 95% confidence interval [CI],0.99–1.10) or between preclinical pregnancy vaccination and their matched controls (1.02; 95% CI, 0.96–1.08). mRNA and viral vector vaccines have shown similar risks for early abortive outcomes and miscarriages. @*Conclusion@#Our findings have provided compelling evidence regarding the effectiveness and safety of COVID-19 vaccination prior to and during early pregnancy. Further research is required to extend the safety and efficacy profiles of COVID-19 vaccines to pregnant women and their babies.
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Background@#This retrospective observational matched-cohort study of 2,151,216 individuals from the Korean coronavirus disease 2019 (COVID-19) vaccine effectiveness cohort aimed to evaluate the comparative effectiveness of the COVID-19 bivalent versus monovalent vaccines in providing additional protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, critical infection, and death in Korea. @*Methods@#Among individuals, those vaccinated with COVID-19 bivalent vaccines were matched in a 1:1 ratio with those who were vaccinated with monovalent vaccines (bivalent vaccines non-recipients) during the observation period. We fitted a time-dependent Cox proportional-hazards model to estimate hazard ratios (HRs) of COVID-19 outcomes for infection, critical infection, and death, and we defined vaccine effectiveness (VE) as 1–HR. @*Results@#Compared with the bivalent vaccination group, the incidence proportions in the monovalent vaccination group were approximately three times higher for infection, nine times higher for critical infection, and 11 times higher for death. In the early stage of bivalent vaccination, relative VE of bivalent vaccine against monovalent vaccine was 42.4% against SARS-CoV-2 infection, 81.3% against critical infection, and 85.3% against death. In addition, VE against critical infection and death according to the elapsed period after bivalent vaccination was maintained at > 70%. @*Conclusion@#The bivalent booster dose provided additional protection against SARS-CoV-2 infections, critical infections, and deaths during the omicron variant phase of the COVID-19 pandemic.
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Background@#There is difference in the incidence of multi-system inflammatory syndrome in children (MIS-C) in patients with different variants of severe acute respiratory syndrome coronavirus 2, however, little is known about the epidemiology in Asian countries. We investigated and compared the epidemiology of the MIS-C during omicron-dominant period with that of previous periods in South Korea. @*Methods@#We obtained clinical, epidemiological and laboratory data on MIS-C cases from national MIS-C surveillance in South Korea. We defined pre-delta period as January 2020–May 2021; delta period as June 2021–December 2021; and omicron period as January 2022–April 2022. We describe the clinical characteristics and outcomes of MIS-C patients by period. @*Results@#A total of 91 cases were assessed to be MIS-C cases. Number of MIS-C cases have increased from six cases during pre-delta period to 66 cases during omicron period, while the incidence rate (the number of MIS-C cases per 100,000 cases of reported coronavirus disease 2019) has decreased from 38.5 cases per 100,000 (95% confidence interval [CI], 14.1–83.9) during pre-delta period to 1.6 cases per 100,000 (95% CI, 1.2–2.0) during omicron periods. During pre-delta period, 66.7% and 100% had hypotension and gastrointestinal involvement, respectively; while during omicron period, 12.1% and 6.1% had such clinical manifestations. Fifty percent of pre-delta MIS-C patients were taken intensive care unit (ICU) cares, while 10.6% of patients during omicron periods were in ICUs. @*Conclusion@#Omicron period were associated with less severe clinical manifestation compared to pre-delta and delta periods. Although incidence rate of MIS-C was lower for the omicron period than pre-delta and delta periods, number of patients reported with MIS-C may pose a substantial clinical burden.
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Purpose@#This article was to collect data on the safety of coronavirus disease 2019 (COVID-19) vaccines in children with underlying medical conditions. @*Methods@#We constructed a prospective cohort of children and adolescents aged 5 to 19 years who had received at least one dose of COVID-19 vaccine. Patients diagnosed with and treated for chronic kidney disease, autoimmune disease, or other chronic conditions at the Seoul National University Children’s Hospital were recruited from June to December 2022. A mobile survey questionnaire was sent to their guardians. The presence of adverse events on the day (day 0), 3 weeks (day 21), and 6 months (day 180) after the 1st dose of COVID-19 vaccine was recorded by the guardians. @*Results@#A total of 73 children participated. The median age was 14 years, and 64.4% of the patients were male. On the day of immunization, 65.8% of the patients reported at least one adverse event. Pain at the injection site, fatigue, headache, arthralgia, and myalgia were the most common symptoms. The prevalence of adverse events decreased over time (65.8% on day 0, 27.4% between days 0 and 21, and 24.6% between days 21 and 180). Severe acute respiratory syndrome coronavirus 2 infection after the 1st dose occurred in 17 patients (23.3%) and one of the patients (5.88%) was hospitalized due to infection. @*Conclusions@#Adverse events after COVID-19 vaccination were generally mild in children and adolescents with underlying medical conditions. Our findings provide evidence for the safety of COVID-19 vaccination in the vulnerable pediatric population.
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We conducted a cohort study to assess vaccine effectiveness (VE) of coronavirus disease 2019 vaccine combinations on severe acute respirator y syndrome coronavirus 2 critical infection and death among elderly population in Korea. From Januar y to August 2022, VE against death for 4 doses mRNA recipients was 96.1%, whereas 1-dose viral vector + 3-dose mRNA recipients had VE of 90.8%.
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Background@#Although coronavirus disease 2019 (COVID-19) vaccines have been distributed worldwide under emergency use authorization, the real-world safety profiles of mRNA vaccines still need to be clearly defined. We aimed to identify the overall incidence and factors associated with adverse events (AEs) following mRNA COVID-19 vaccination. @*Methods@#We conducted web-based survey from December 2 to 10 in 2021 with a 2,849 nationwide sampled panel. Study participants were individuals who had elapsed at least twoweeks after completing two dosing schedules of COVID-19 vaccination aged between 18–49 years. We weighted the participants to represent the Korean population. The outcome was the overall incidence of AEs following mRNA COVID-19 vaccination and associated factors.We estimated the weighted odds ratios (ORs) using multivariable logistic regression models to identify the factors associated with AEs. @*Results@#Of the 2,849 participants (median [interquartile range] age, 35 [27–42] years; 51.6% male), 90.8% (n = 2,582) for the first dose and 88.7% (n = 2,849) for the second dose reported AEs, and 3.3% and 4.3% reported severe AEs, respectively. Occurrence of AEs was more prevalent in mRNA-1273 (OR, 2.06; 95% confidence interval [CI], 1.59–2.67 vs. BNT162b2), female sex (1.88; 1.52–2.32), and those with dermatologic diseases (2.51; 1.32–4.77). History of serious allergic reactions (1.96; 1.06–3.64) and anticoagulant medication use (4.72; 1.92–11.6) were associated with severe AEs. @*Conclusion@#Approximately 90% of participants reported AEs following mRNA COVID-19 vaccination. Substantial factors, including vaccine type (mRNA-1273), female sex, and dermatologic diseases were associated with AEs. Our findings could aid policymakers in establishing vaccination strategies tailored to those potentially susceptible to AEs.
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Coronavirus disease 2019 (COVID-19) has been a global pandemic for over 2 years. During the Omicron (B.1.1.529) variant-predominant period in South Korea, confirmed cases among children and adolescents surged. This review found that, although younger children may be less susceptible to COVID-19 than adolescents, more research is needed on the role of children and adolescents in the disease’s spread. Detailed epidemiological information about the transmissibility of the novel severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) strain in children and adolescents is currently scarce, and more research is needed on the role of children and adolescents in disease’s spread. There may be a difference in the proportion of cases with severe disease requiring hospitalization depending on the dominant mutant strain; however, COVID-19 generally presents with a mild-to-moderate course in children aged 5–11 years old.
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Background@#The emergence of new infectious diseases threatens public health, increasing socioeconomic damage, and national risks. This study aimed to develop an evidence-based risk assessment tool to quickly respond to new infectious diseases. @*Methods@#The risk elements were extracted by reviewing the risk assessment methods of the World Health Organization, United States, Europe, United Kingdom, and Germany, and the validity and priority of elements were determined through expert meetings and Delphi surveys. Then, the scale and level for each risk element were defined and a final score calculation method according to the risk evaluation result was derived. The developed risk assessment tool was verified using data at the time of domestic transmission of an emerging infectious disease. @*Results@#In case of spread of actual infectious diseases, priority is determined based on the criticality of the elements in each area of transmissibility and severity, from which the weighted score of the risk assessment is derived. Then, the risk score for each element was calculated by multiplying the average value of the risk evaluation by its weight and the evaluation risk assessment score for the two areas was calculated. At last, the final score is plotted in a matrix where the x-axis indicates the transmissibility and the y-axis the severity and plotted on the coordinate plane for time series use. @*Conclusion@#With respect to transmissibility and severity, this risk assessment method to respond to new and re-emerging infectious diseases enables rapid and evidence-based evaluation by quantitatively and qualitatively assessing various risk elements.
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Following nonpharmaceutical intervention (NPI) to mitigate coronavirus disease 2019 has led to drastic reduction in incidence of communicable disease. Intussusception is commonly preceded by infectious pathogens. Indirect effect from NPI implementation on incidence of intussusception has not been understood fully. We conducted a cohort study to estimate the impact of NPI on incidence of intussusception in Korean children. The net risk ratio of intussusception incidence for 2020 compared to 2010–2019 was 0.53 (95% confidence interval [CI], 0.43–0.64) for boys and 0.56 (95% CI, 0.44–0.71) for girls (P for difference = 0.017). Our study showed an association between NPI implementation and reduction of intussusception incidence, with more profound reduction in boys compared to girls.
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Background@#Despite the extraordinary speed of mass vaccination efforts, an outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta variant in a vaccinee with coronavirus disease 2019 (COVID-19) mRNA vaccine was identified in an adult day service center (ADSC) of Jeju, South Korea. The primary objective of this study was to investigate the epidemiologic features in infection-vulnerable facilities with a high vaccination rate of BNT162b2 mRNA COVID-19 vaccine. The second was to estimate the secondary transmission prevention effect of the vaccine in the household members by vaccination status. @*Methods@#We included all ADSC participants, staff and their household members. All COVID-19 infected cases were confirmed by reverse transcriptase polymerase chain reaction.We calculated attack rate in ADSC and the secondary attack rate (SAR) in household members by vaccination status. @*Results@#Among a total of 42 participants and 16 staff, of which 96.6% were fully vaccinated with BNT162b2 mRNA COVID-19 vaccine, 12 symptomatic cases and 13 asymptomatic confirmed cases of COVID-19 were found. The attack rate was 43.1%, with 13 isolates identified as SARS-CoV-2 virus, delta variant. The SAR in unvaccinated and partially vaccinated household members were 27.8% (5/18) and 25.0% (5/20), respectively, while the SAR in fully vaccinated household members was 12.5% (1/8). @*Conclusion@#We describe a SARS-CoV-2 delta variant outbreak in ADSC with high vaccine coverage rate, characterized by high infection rate, high transmissibility, and low clinical severity. The outbreak proceeded to unvaccinated or partially vaccinated household members, emphasizing the need for immunizing close contacts of high-risk groups.
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Background@#Coronavirus disease 2019 (COVID-19) is generally asymptomatic or mild in otherwise healthy children, however, severe cases may occur. In this study, we report the clinical characteristics of children classified as critical COVID-19 in Korea to provide further insights into risk factors and management in children. @*Methods@#This study was a retrospective case series of children 97% for infant) and one was overweight (BMI 21.3). All patients had fever, six patients had dyspnea or cough and other accompanied symptoms included sore throat, headache, lethargy and myalgia. Radiologic findings showed pneumonia within 1–8 days after symptom onset. Pneumonia progressed in these children for 2–6 days and was improved within 5–32 days after diagnosis. Among the eight critical cases, remdesivir was administered in six cases.Steroids were provided for all cases. Inotropics were administered in one case. Six cases were treated with noninvasive mechanical ventilator and three required mechanical ventilator. One case required ECMO due to acute respiratory distress syndrome. All cases were admitted to the intensive care unit and admission period ranged from 9–39 days. Among all critical COVID-19 cases < 18 years of age, there were no fatal cases. @*Conclusion@#To develop appropriate policies for children in the COVID-19 pandemic, it is important to monitor and assess the clinical burden in this population.
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In Korea, children aged 5 to 11 have been vaccinated against coronavirus disease 2019 (COVID-19) from March 2022. Due to this age group not being at a high risk of developing severe COVID-19 symptoms, each major country has different, circumstance dependent, immunization policies for children. In this review, the COVID-19 vaccination policies for 5–11 years old children in major countries were reviewed and considerations were presented for Korea, where children 5–11 years old are starting to get vaccinated against COVID-19.
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Purpose@#To evaluate the efficacy and safety of coronavirus disease 2019 (COVID-19) vaccines in children aged 5–11 years, a rapid systematic review was conducted on published clinical trials of COVID-19 vaccines and studies that analyzed real-world data on adverse events after COVID-19 vaccination. @*Methods@#A systematic search was conducted on medical literature in international (Ovid-MEDLINE) and pre-published literature databases (medRxiv), followed by handsearching up to January 4, 2022. We used terms including COVID-19, severe acute respiratory syndrome coronavirus 2, and vaccines, and the certainty of evidence was graded using the GRADE approach. @*Results@#A total of 1,675 studies were identified, of which five were finally selected. Among the five studies, four consisted of data from clinical trials of each of the four types of COVID-19 vaccines (BNT162b2, mRNA-1273, CoronaVac, and BBIBP-CorV). The remaining study consisted of real-world data on the safety of the BNT162b2 vaccine in children aged 5–11 years. This systematic review identified that COVID-19 vaccines in recipients aged 5–11 years produced a favorable immune response, and were vaccines were effective against COVID-19. The safety findings for the BNT162b2 vaccine in children and early adolescents aged 5–11 years were similar to those data noted in the clinical trial. @*Conclusions@#There is limited data on COVID-19 vaccines in children aged 5–11 years.Consequently continuous and comprehensive monitoring is necessary for the evaluation of the safety and effectiveness of the COVID-19 vaccines.
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Purpose@#During the coronavirus disease 2019 (COVID-19) pandemic, we conducted a Delphi survey that included the experts from the field of COVID-19 immunization in children aged 5–11 years. The aim was to organize collective expert opinions on COVID-19 vaccination in young children in the Republic of Korea, and so thus assist the vaccination policy. @*Methods@#The panels included pediatric infectious disease specialists, preventive medicine experts, infectious disease physicians, and COVID-19 vaccine experts consulting the Ministry of Health and Welfare. The Delphi survey was conducted online using a questionnaire from February 14 to February 27, 2022. @*Results@#The Delphi panels agreed that children were vulnerable to COVID-19, and the severity of illness was modest. Furthermore the panels reported that children with chronic illness were more susceptible to a worsening clinical course. There were generally positive opinions on the effectiveness of COVID-19 vaccination in children aged 5–11 years, and experts gathered a slightly positive opinion that the adverse events of pediatric COVID-19 were not numerous. The benefits of COVID-19 vaccination were evaluated at a level similar to the potential risks in children.Currently, the only approved mRNA platform vaccine in children seemed to be sustainable; however, the recombinant protein platform COVID-19 vaccines were evaluated as better options. @*Conclusions@#Due to the surge of the Omicron variant and an increase in pediatric cases, the COVID-19 vaccination in young children may have to be considered. Panels had neutral opinions regarding the COVID-19 vaccination in children aged 5–11 years. Thus monitoring of the epidemiology and the data about the safety of COVID-19 vaccination should be continued.
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Croup is an acute upper respiratory disease primarily caused by the parainfluenza virus.Owing to inflammation and edema of the upper airways, children present with barky cough and stridor, and some may experience respiratory distress. We investigated children aged < 5 years with coronavirus disease 2019 (COVID-19) admitted to two hospitals in Seoul, South Korea, and observed a spike in croup cases during the omicron surge. Among the 569 children admitted from March 1, 2021 to February 25, 2022, 21 children (3.7%) had croup, and the proportion of croup cases was significantly higher during the omicron wave than that during the delta wave (12.4% vs. 1.2%, P < 0.001). With the immediate administration of corticosteroids and epinephrine via nebulizer, the symptoms improved rapidly. During the current omicron surge, careful monitoring of the symptoms of croup in young children is needed for the diagnosis of COVID-19 and its timely management.