Immune pathogenesis of COVID-19-related multisystem inflammatory syndrome in children

Risks of Kawasaki disease and multisystem inflammatory syndrome in pediatric patients with COVID-19 infection: A TriNetX based cohort study

BACKGROUND

The associations of coronavirus disease (COVID-19) with Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) remain unclear. Few large-scale studies have estimated the cumulative incidence of MIS-C and KD after COVID-19 in children.

METHODS

Data were obtained from TriNetX. After propensity score matching was completed, data from 258 645 patients with COVID-19 (COVID-19 group) and 258 645 patients without COVID-19 (non-COVID-19 group) were analyzed using Cox regression. Hazard ratio (HR), 95% CI, and cumulative incidence of MIS-C and KD were calculated for both groups. A stratified analysis was performed to validate the results.

RESULTS

After matching for age at baseline and sex, the risks of MIS-C and KD were higher in the COVID-19 group than in the non-COVID-19 group (HR: 3.023 [95% CI, 2.323-3.933] and 1.736 [95% CI, 1.273-2.369], respectively). After matching for age at baseline, sex, race, ethnicity, and comorbidities, the risks of MIS-C and KD remained significantly higher in the COVID-19 group than in the non-COVID-19 group (HR: 2.899 [95% CI, 2.173-3.868] and 1.435 [95% CI, 1.030-2.000]). When stratified by age, the risk of MIS-C was higher in the COVID-19 group-for patients aged >5 years and ≤5 years (HR: 2.399 [95% CI, 1.683-3.418] and 2.673 [95% CI, 1.737-4.112], respectively)-than in the non-COVID-19 group. However, the risk of KD was elevated only in patients aged ≤5 years (HR: 1.808; 95% CI, 1.203-2.716). When stratified by COVID-19 vaccination status, the risks of MIS-C and KD were elevated in unvaccinated patients with COVID-19 (HR: 2.406 and 1.835, respectively).

CONCLUSION

Patients with COVID-19 who are aged <18 and ≤5 years have increased risks of MIS-C and KD, respectively. Further studies are required to confirm the role of COVID-19 in the pathogenesis of MIS-C and KD.

Long-Term effects of COVID-19: a review of current perspectives and mechanistic insights

Although SARS-CoV-2, responsible for COVID-19, is primarily a respiratory infection, a broad spectrum of cardiac, pulmonary, neurologic, and metabolic complications can occur. More than 50 long-term symptoms of COVID-19 have been described, and as many as 80% of patients may develop ≥1 long-term symptom. To summarize current perspectives of long-term sequelae of COVID-19, we conducted a PubMed search describing the long-term cardiovascular, pulmonary, gastrointestinal, and neurologic effects post-SARS-CoV-2 infection and mechanistic insights and risk factors for the above-mentioned sequelae. Emerging risk factors of long-term sequelae include older age (≥65 years), female sex, Black or Asian race, Hispanic ethnicity, and presence of comorbidities. There is an urgent need to better understand ongoing effects of COVID-19. Prospective studies evaluating long-term effects of COVID-19 in all body systems and patient groups will facilitate appropriate management and assess burden of care. Clinicians should ensure patients are followed up and managed appropriately, especially those in at-risk groups. Healthcare systems worldwide need to develop approaches to follow-up and support patients recovering from COVID-19. Surveillance programs can enhance prevention and treatment efforts for those most vulnerable.

Cardiovascular Manifestations of Multisystem Inflammatory Syndrome in Children: A Single-Center Bulgarian Study

Background and objectives: Multisystem inflammatory syndrome in children (MIS-C) poses challenges to the healthcare system, especially with frequent heart involvement. The current retrospective observational study aims to summarize the type and degree of cardiovascular involvement in children with MISC and to find possible associations between laboratory, inflammatory, and imaging abnormalities and the predominant clinical phenotype using a cluster analysis. Material and methods: We present a retrospective observational single-center study including 51 children meeting the MIS-C criteria. Results: Fifty-three percent of subjects presented with at least one sign of cardiovascular involvement (i.e., arterial hypotension, heart failure, pericardial effusion, myocardial dysfunction, pericarditis without effusion, myocarditis, coronaritis, palpitations, and ECG abnormalities). Acute pericarditis was found in 30/41 of the children (73%) assessed using imaging: 14/30 (46.7%) with small pericardial effusion and 16/30 (53.3%) without pericardial effusion. The levels of CRP were significantly elevated in the children with pericarditis (21.6 ± 13 mg/dL vs. 13.9 ± 11 mg/dL, p = 0.035), and the serum levels of IL-6 were higher in the children with small pericardial effusion compared to those without (191 ± 53 ng/L vs. 88 ± 27 ng/L, p = 0.041). Pericarditis with detectable pericardial effusion was significantly more frequent in the female vs. male subjects, 72% vs. 30% (p = 0.007). The hierarchical clustering analysis showed two clusters: Cluster 1 includes the children without cardiovascular symptoms, and Cluster 2 generalizes the MIS-C children with mild and severe cardiovascular involvement, combining pericarditis, myocarditis, heart failure, and low blood pressure. Also, subjects from Cluster 2 displayed significantly elevated levels of fibrinogen (5.7 ± 0.3 vs. 4.6 ± 0.3, p = 0.03) and IL-6 (158 ± 36 ng/mL vs. 66 ± 22 ng/mL, p = 0.032), inflammatory markers suggestive of a cytokine storm. Conclusions: Our results confirm that children with oligosymptomatic MIS-C or those suspected of long COVID-19 should be screened for possible cardiological involvement.

The protective effect of COVID-19 vaccines on developing multisystem inflammatory syndrome in children (MIS-C): a systematic literature review and meta-analysis

OBJECTIVE

To review whether the current COVID-19 vaccines can prevent the occurrence of multisystem inflammatory syndrome in children (MIS-C) and adolescents.

METHODS

A systematic literature review and meta-analysis were performed. The data were abstracted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Primary outcome was the efficacy of COVID-19 vaccination in preventing MIS-C development. The search was performed in PubMed and Embase.

RESULTS

The review yielded 13 studies, which were included for critical appraisal and data extraction. The available studies showed a reduced incidence of MIS-C after mRNA COVID-19 vaccination in children aged 12-18 years. Four studies were eligible for meta-analysis and the pooled odds ratio for MIS-C in vaccinated children compared to unvaccinated children was 0.04 (95% confidence interval: 0.03-0.06). Additionally, the risk of MIS-C as an adverse effect of vaccination was much lower compared to the risk of MIS-C post-infection.

CONCLUSIONS

Our systematic review highlights the current available evidence on the efficacy of COVID-19 vaccination in preventing MIS-C. The published studies so far - mainly conducted during the Delta wave - indicate that (original strain) COVID-19 mRNA vaccines in children are safe and associated with significantly less development of MIS-C. These findings further reinforce the recommendation for COVID-19 vaccination in children, which should be promoted and largely supported.

Six-month multidisciplinary follow-up in multisystem inflammatory syndrome in children: An Italian single-center experience

Background

A severe multisystem inflammatory syndrome in children (MIS-C) related to SARS-CoV-2 has been described after infection. A limited number of reports have analyzed the long-term complications related to pro-inflammatory status in MIS-C. We evaluated multiorgan impairment at the 6-month follow-up in MIS-C.

Methods

We enrolled 33 pediatric patients consecutively hospitalized for MIS-C and monitored for almost 6 months. The inter-relationship of patient's features and disease severity at admission with long term complications was studied by multivariate analysis.

Results

Endo-metabolic derangement, cardiac injury, respiratory, renal and gastrointestinal manifestations and neurological involvement are part of the initial presentation. The most abnormalities appear to resolve within the first few weeks, without significant long term dysfunction at the 6-months follow-up, except for endocrine (non-thyroidal illness syndrome in 12.1%, insulin resistance in 21.2%) and neurological system (27.3% cognitive or psychological, behavioral, adaptive difficulties). Endocrine and heart involvement at admission represent a significant factor on the long term sequelae; however no association between severity score and long-term outcome was noted.

Conclusions

The severity of initial clinical presentation may be associated to organ domain, however it is not related to long term sequelae. The prevalent organ restoration supports a predominant indirect immune-mediated injury triggered by a systemic inflammatory response; however a direct damage due to the viral entry could be not excluded. Eventhought our preliminary results seem to suggest that MIS-C is not a long-term risk condition for children health, a longer follow-up is mandatory to confirm this hypothesis.

Research trends on causes of Kawasaki disease in the COVID-19 era: focus on viral infections

Despite studies on the etiology of Kawasaki disease (KD) ongoing for half a century since its discovery, its cause has not yet been clearly identified. Although the clinical, epidemiological, and pathophysiological characteristics of KD are presumed to be closely related to infectious diseases, studies of various pathogens to identify its etiology have been actively conducted. To date, bacteria, fungi, and viruses have been investigated to determine the relationship between KD and infection, among which viruses have attracted the most attention. In particular, during the coronavirus disease 2019 pandemic, there were many reports in Europe of a sharp increase in cases of Kawasaki-like disease (KLD), while conflicting reports that the prevalence of KD decreased due to thorough "social distancing" or "wearing mask" in Asian countries drew more attention regarding the association between KD and viral infection. Therefore, the differential diagnosis of KD from KLD with these similar spectra has become a very important issue; simultaneously, research to solve questions about the association between KD and viral infections, including sudden acute respiratory syndrome coronavirus 2, is drawing attention again. Moreover, a new concept has emerged that immune responses occurring in patients with KD can be caused by the pathogen itself as well as host cells damaged by infection. This paper summarizes the research trends into KD etiology and related pathophysiology, especially its association with viral infections, and present future research tasks to increase our understanding of KD.

Physiologic profile associated with severe multisystem inflammatory syndrome in children: a retrospective study

OBJECTIVE

The purpose of this study was to describe the clinical presentation and physiologic profile of individuals with varying degrees of severity of multisystem inflammatory syndrome in children (MIS-C).

METHODS

We performed a retrospective study of children diagnosed with MIS-C admitted to a single quaternary children's hospital from May 2020 to April 2021. We created an MIS-C severity score using the following parameters: hospital admission status (e.g., floor vs intensive care unit), need for inotropic or vasoactive medications, and need for mechanical ventilation. Univariate and multivariate analyses were performed to associate risk factors corresponding to the MIS-C severity score.

RESULTS

The study included 152 children who were followed for 14 days post hospital admission. A stepwise forward selection process identified seven physiologic variables associated with "severe" MIS-C according to a logistic regression. Specifically, a combination of elevated creatinine (p = 0.013), international normalized ratio (p = 0.002), brain natriuretic peptide (p = 0.001), white blood cell count (p = 0.009), ferritin (p = 0.041), respiratory rate (p = 0.047), and decreased albumin (p = 0.047) led to an excellent discrimination between mild versus severe MIS-C (AUC = 0.915).

CONCLUSION

This study derived a physiologic profile associated with the stratification of MIS-C severity.

IMPACT

Based on a cohort of 152 individuals diagnosed with MIS-C, this study derived a nomenclature that stratifies the severity of MIS-C. Investigated demographic, presentational vital signs, and blood analytes associated with severity of illness. Identification of a multivariate physiologic profile that strongly associates with MIS-C severity. This model allows the care team to recognize patients likely to require a higher level of intensive care.

Risk of paediatric multisystem inflammatory syndrome (PIMS-TS) during the SARS-CoV-2 alpha and delta variant waves: National observational and modelling study, 2020-21, England

Objectives

Paediatric Multisystem Inflammatory Syndrome (PIMS-TS) is a rare life-threatening complication that typically occurs several weeks after SARS-CoV-2 infection in children and young people (CYP). We used national and regional-level data from the COVID-19 pandemic waves in England to develop a model to predict PIMS-TS cases.

Methods

SARS-CoV-2 infections in CYP aged 0-15 years in England were estimated using the PHE-Cambridge real-time model. PIMS-TS cases were identified through the British Paediatric Surveillance Unit during (March-June 2020) and through Secondary Uses Services (SUS) from November 2020. A predictive model was developed to estimate PIMS-TS risk and lag times after SARS-CoV-2 infections.

Results

During the Alpha wave, the model accurately predicted PIMS-TS cases (506 vs. 502 observed cases), with a median estimated risk of 0.038% (IQR, 0.037-0.041%) of paediatric SARS-CoV-2 infections. For the Delta wave, the median risk of PIMS-TS was significantly lower at 0.026% (IQR, 0.025-0.029%), with 212 observed PIMS-TS cases compared to 450 predicted by the model.

Conclusions

The model accurately predicted national and regional PIMS-TS cases in CYP during the Alpha wave. PIMS-TS cases were 53% lower than predicted during the Delta wave. Further studies are needed to understand the mechanisms of the observed lower risk with the Delta variant.

Drugs for the prevention and treatment of COVID-19 and its complications: An update on what we learned in the past 2 years

The COVID-19 Committee of the Lincei Academy has reviewed the scientific evidence supporting the efficacy and safety of existing and new drugs/biologics for the preventing and treating of COVID-19 and its complications. This position paper reports what we have learned in the field in the past 2 years. The focus was on, but not limited to, drugs and neutralizing monoclonal antibodies, anti-SARS-CoV-2 agents, anti-inflammatory and immunomodulatory drugs, complement inhibitors and anticoagulant agents. We also discuss the risks/benefit of using cell therapies on COVID-19 patients. The report summarizes the available evidence, which supports recommendations from health authorities and panels of experts regarding some drugs and biologics, and highlights drugs that are not recommended, or drugs for which there is insufficient evidence to recommend for or against their use. We also address the issue of the safety of drugs used to treat underlying concomitant conditions in COVID-19 patients. The investigators did an enormous amount of work very quickly to understand better the nature and pathophysiology of COVID-19. This expedited the development and repurposing of safe and effective therapeutic interventions, saving an impressive number of lives in the community as well as in hospitals.

Multisystem inflammatory syndrome in children (MIS-C) and neonates (MIS-N) associated with COVID-19: optimizing definition and management

During the SARS-CoV-2-associated infection (COVID-19), pandemic initial reports suggested relative sparing of children inversely related to their age. Children and neonates have a decreased incidence of SARS-CoV-2 infection, and if infected they manifested a less severe phenotype, in part due to enhanced innate immune response. However, a multisystem inflammatory syndrome in children (MIS-C) or paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 emerged involving coronary artery aneurysms, cardiac dysfunction, and multiorgan inflammatory manifestations. MIS-C has many similarities to Kawasaki disease and other inflammatory conditions and may fit within a spectrum of inflammatory conditions based on immunological results. More recently neonates born to mothers with SARS-CoV-2 infection during pregnancy demonstrated evidence of a multisystem inflammatory syndrome with raised inflammatory markers and multiorgan, especially cardiac dysfunction that has been described as multisystem inflammatory syndrome in neonates (MIS-N). However, there is a variation in definitions and management algorithms for MIS-C and MIS-N. Further understanding of baseline immunological responses to allow stratification of patient groups and accurate diagnosis will aid prognostication, and inform optimal immunomodulatory therapies. IMPACT: Multisystem inflammatory system in children and neonates (MIS-C and MIS-N) post COVID require an internationally recognized consensus definition and international datasets to improve management and plan future clinical trials. This review incorporates the latest review of pathophysiology, clinical information, and management of MIS-C and MIS-N. Further understanding of the pathophysiology of MIS-C and MIS-N will allow future targeted therapies to prevent and limit clinical sequelae.

Clinical presentation and short-term outcomes of multisystemic inflammatory syndrome in children in Lagos, Nigeria during the COVID-19 pandemic: A case series

Background

Multisystemic inflammatory syndrome in children (MIS-C) has increasingly been documented globally with the progression of the COVID-19 pandemic and a significant proportion of cases have been noted in children of Black descent. There has been a noticeable discrepancy in the presentation and outcomes of COVID-19 infection in sub-Saharan Africa compared to the rest of the world. We documented the demography, clinical features, laboratory and imaging findings, therapeutic management, and short-term outcomes of paediatric patients with MIS-C diagnosed during the COVID-19 pandemic in Lagos, Nigeria.

Methods

We carried out a retrospective review of MIS-C cases seen in nine public and private hospitals in Lagos from July 10, 2020 to July 30, 2021. Data on clinical presentation, laboratory investigations, therapy as well as outcomes at 2 weeks, 6 weeks, 3 months and 6 months were analyzed.

Findings

28 children and adolescents with median age of 7·5 (IQR 2·3 - 9·4) years were diagnosed with MIS-C. MIS-C was suspected in 24 patients (85·7%) at initial clinical evaluation and mucocutaneous, gastrointestinal and cardiovascular manifestations were identified in 75·0%, 71·4% and 89·3% of patients respectively. Acute kidney injury and aseptic meningitis were noted in 32·1% and 17·9% of patients respectively. Cardiac manifestations at presentation included coronary dilatation and pericardial effusion in 46·4% each, ventricular dysfunction (32·1%), atrioventricular valve regurgitation (25·0%), prolonged QTc interval (40·0%) and first-degree atrioventricular block (16·0%). Therapy included aspirin in 89·3%, steroids in 75·0% and intravenous immunoglobulin (IVIG) infusion in 60·7%. All patients survived and were discharged after a mean of 11·14 (SD 5·65) days. Frequency of coronary dilatation had reduced from 46·4% to 7·1% by 3 months follow up and prolonged QTc interval persisted until the 6 week follow up in 4.5% of patients. Echocardiogram and electrocardiogram findings were normal in all patients assessed at 6 months follow up.

Interpretation

MIS-C is an important diagnosis in children presenting with prolonged fever during the COVID-19 pandemic. Cardiovascular manifestations occurred in several children with MIS-C and improved by 6 months follow up. Early diagnosis and prompt institution of a combination of antiplatelet therapy, steroids and IVIG appear to be beneficial.

Funding

None.

Multisystem Inflammatory Syndrome in Children (MIS-C) with COVID-19: A Single-Center Experience

Objective Multisystem inflammatory syndrome in children (MIS-C) is a hyperinflammatory syndrome associated with multiorgan damage that occurs following coronavirus disease 2019 (COVID-19). Research on clinical and laboratory findings, and imaging studies, aiming to predict the progression to severe disease state is limited. This study recruited patients with MIS-C who presented with mild or severe symptoms from a single center in Turkey and evaluated factors related to their symptoms.

Methods This retrospective study included 25 pediatric patients with mild and severe presentations of MIS-C. We explored the differences in demographic and clinical data on clinical severity to understand their possible diagnostic and prognostic values.

Results Patients with MIS-C had cardiovascular symptoms (68%), gastrointestinal symptoms (64%), dermatologic/mucocutaneous findings (64%), lung involvement (36%), and neurological symptoms (16.0%). About 45.1% of patients with MIS-C had manifestations that overlapped with Kawasaki disease. Eleven patients (44%) were admitted to the intensive care unit, and one (4%) patient died. Grouping based on clinical severity did not differ statistically in terms of gender, age, height, weight, body mass index, and duration of hospital stay. Procalcitonin and ferritin levels correlated with disease severity. The receiver operating characteristic curve for D-dimer gave the highest value of area under the curve, among other biomarkers. The cutoff value for D-dimer was determined as more than 6780.

Conclusions Although COVID-19 is usually mild in children, some can be severely affected, and clinical severity in MIS-C can differ from mild to severe multisystem involvement. This study shows that procalcitonin, ferritin, and D-dimer levels may give us information about disease severity.

Mesenteric Lymphadenitis Presenting as Acute Abdomen in a Child with Multisystem Inflammatory Syndrome

Multisystem inflammatory syndrome in children (MIS-C) may develop as a rare complication following COVID-19. MIS-C presentation varies substantially, but fever and gastrointestinal symptoms are the most prominent. Indeed, gastrointestinal involvement may be severe enough to present as acute abdomen, posing challenges to clinicians. We present herein the case of a healthy five-year-old male who presented with fever, vomiting, and abdominal pain, resembling acute abdomen. The patient had no history of SARS-CoV-2 infection or exposure, and MIS-C diagnosis was initially surpassed unnoticed. The patient underwent exploratory laparotomy that only revealed mesenteric lymphadenitis. Postoperatively, the patient met the clinical and laboratory diagnostic criteria of MIS-C. SARS-CoV-2 exposure was serologically confirmed and MIS-C treatment was commenced, resulting in defervescence and a satisfactory outcome. In young patients presenting with acute abdomen, surgeons should be aware of MIS-C, so that earlier diagnosis and appropriate treatment are made prior to surgical interventions.

Reported cases of multisystem inflammatory syndrome in children aged 12-20 years in the USA who received a COVID-19 vaccine, December, 2020, through August, 2021: a surveillance investigation

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a hyperinflammatory condition associated with antecedent SARS-CoV-2 infection. In the USA, reporting of MIS-C after vaccination is required under COVID-19 vaccine emergency use authorisations. We aimed to investigate reports of individuals aged 12-20 years with MIS-C after COVID-19 vaccination reported to passive surveillance systems or through clinician outreach to the US Centers for Disease Control and Prevention (CDC).

METHODS

In this surveillance activity, we investigated potential cases of MIS-C after COVID-19 vaccination reported to CDC's MIS-C national surveillance system, the Vaccine Adverse Event Reporting System (co-administered by CDC and the US Food and Drug Administration), and CDC's Clinical Immunization Safety Assessment Project. A multidisciplinary team adjudicated cases by use of the CDC MIS-C definition. Any positive SARS-CoV-2 serology test satisfied case criteria; although anti-nucleocapsid antibodies indicate previous SARS-CoV-2 infection, anti-spike protein antibodies indicate either past or recent infection or COVID-19 vaccination. We describe the demographic and clinical features of cases, stratified by laboratory evidence of SARS-CoV-2 infection. To calculate the reporting rate of MIS-C, we divided the count of all individuals meeting the MIS-C case definition, and of those without evidence of SARS-CoV-2 infection, by the number of individuals aged 12-20 years in the USA who received one or more COVID-19 vaccine doses up to Aug 31, 2021, obtained from CDC national vaccine surveillance data.

FINDINGS

Using surveillance results from Dec 14, 2020, to Aug 31, 2021, we identified 21 individuals with MIS-C after COVID-19 vaccination. Of these 21 individuals, median age was 16 years (range 12-20); 13 (62%) were male and eight (38%) were female. All 21 were hospitalised: 12 (57%) were admitted to an intensive care unit and all were discharged home. 15 (71%) of 21 individuals had laboratory evidence of past or recent SARS-CoV-2 infection, and six (29%) did not. As of Aug 31, 2021, 21 335 331 individuals aged 12-20 years had received one or more doses of a COVID-19 vaccine, making the overall reporting rate for MIS-C after vaccination 1·0 case per million individuals receiving one or more doses in this age group. The reporting rate in only those without evidence of SARS-CoV-2 infection was 0·3 cases per million vaccinated individuals.

INTERPRETATION

Here, we describe a small number of individuals with MIS-C who had received one or more doses of a COVID-19 vaccine before illness onset; the contribution of vaccination to these illnesses is unknown. Our findings suggest that MIS-C after COVID-19 vaccination is rare. Continued reporting of potential cases and surveillance for MIS-C illnesses after COVID-19 vaccination is warranted.

FUNDING

US Centers for Disease Control and Prevention.

Cardiac manifestations and diagnostic imaging in pediatric inflammatory multisystem syndrome temporally associated with COVID-19: a systematic review

BACKGROUND Several studies have reported pediatric inflammatory multisystem syndrome temporally associated with COVID-19 (PIMS-TS) cases with their cardiac manifestations, but only few studies synthesize the cardiovascular characteristics in children with PIMS-TS. However, detecting cardiac abnormalities is crucial in improving patients' outcomes and reducing mortality. This review aimed to summarize the overall symptoms, laboratory, and workup findings in PIMS-TS patients, focusing on cardiovascular manifestations. METHODS We searched 4 medical databases (PubMed, Science Direct, Medline, and Scielo) and 4 preprint databases (Medrxiv, Research Square, SSRN, and Biorxiv). The literature search was done on November 8, 2021. All case reports, case series, cross-sectional studies, cohort studies, and possible clinical trials published from December 2020 onward that studied PIMS-TS on cardiac manifestation (aged 0–18 years) were included. Studies on multisystem inflammatory syndrome in children, animal studies, and studies without full-text availability were excluded. This review was registered in PROSPERO (CRD42021194468). RESULTS 59 studies were included with a total of 698 patients. The most common cardiovascular findings were the presence of cardiogenic shock (37%) and hypotension (8.5%). Almost all laboratory values were deranged. Cardiac computed tomography scan mostly showed normal results (56%), followed by cardiomegaly with pericardial effusion (14%). Electrocardiography showed normal findings (46%), ST-segment abnormalities (32%), and abnormal T wave (12%). Echocardiography findings showed left ventricle dysfunction (40.6%), which can be considered most significant, followed by pericardial effusion together with pericarditis (11.4%) and tricuspid regurgitation (6.9%). CONCLUSIONS This review found various cardiac abnormalities that may develop during PIMS-TS. Due to these findings, we should be more vigilant and not underestimate the consequences in pediatric COVID-19 patients.

Rare and common manifestations of COVID-19 in children

Introduction

It has been almost 2 years since the first reports on cutaneous manifestations of COVID-19. Those reported in children are different and include macular, papular, lichenoid, vesicular, urticarial, and vascular morphologies, among others. The prognosis of isolated cutaneous involvement in COVID-19 in children is usually self-limiting but the extreme variety of clinical presentations complicates the clinical approach.

Methods

Numerous reviews have been systematically drafted and edited giving the clinicians a future direction for skin presentations during pandemics.

Results and Discussion

Hereby we report the rare and common manifestations of COVID-19 in children and question the recurrence phenomena and age-related distribution of the eruptions.

ELISA-Based Analysis Reveals an Anti-SARS-CoV-2 Protein Immune Response Profile Associated with Disease Severity

Since the start of the COVID-19 pandemic, many studies have investigated the humoral response to SARS-CoV-2 during infection. Studies with native viral proteins constitute a first-line approach to assessing the overall immune response, but small peptides are an accurate and valuable tool for the fine characterization of B-cell epitopes, despite the restriction of this approach to the determination of linear epitopes. In this study, we used ELISA and peptides covering a selection of structural and non-structural SARS-CoV-2 proteins to identify key epitopes eliciting a strong immune response that could serve as a biological signature of disease characteristics, such as severity, in particular. We used 213 plasma samples from a cohort of patients well-characterized clinically and biologically and followed for COVID-19 infection. We found that patients developing severe disease had higher titers of antibodies mapping to multiple specific epitopes than patients with mild to moderate disease. These data are potentially important as they could be used for immunological profiling to improve our knowledge of the quantitative and qualitative characteristics of the humoral response in relation to patient outcome.

Clinical characteristics of children with MIS-C fulfilling classification criteria for macrophage activation syndrome

BACKGROUND

Macrophage activation syndrome (MAS) is a potentially life-threatening complication of various inflammatory disorders, including multisystem inflammatory syndrome in children (MIS-C). MIS-C refractory to treatment should raise suspicion of MAS, which can be fatal if a definitive diagnosis is delayed. Unfortunately, there is a lack of data on MAS in children with MIS-C.

OBJECTIVE

Our study aims to analyze the risk factors for the development of MAS in MIS-C, its clinical course and response to treatment, and identify predictive factors for pediatric intensive care.

MATERIAL AND METHODS

We analyzed data from the Polish MIS-C registry of the MultiOrgan Inflammatory Syndromes COVID-19 Related Study. Patients were diagnosed according to the WHO MIS-C definition and treated according to national guidelines (Polish Pediatric Society) based on international consensus. MAS definition was based on 2016 Classification Criteria for Macrophage Activation Syndrome Complicating Systemic Juvenile Idiopathic Arthritis.

RESULTS

Two-hundred and seventy four children met the study inclusion criteria. Fifty-nine patients fulfilled MAS classification criteria, nine of which required admission to the pediatric intensive care unit (PICU). MIS-C patients with MAS were significantly older than patients without MAS (median 11.2 vs. 8.1 years). Multivariable analysis showed that age, symptoms characteristic of atypical Kawasaki disease, and skin erosions were significant factors associated with MAS in MIS-C patients. Analysis of laboratory parameters showed that on admission, MIS-C patients with MAS had significantly lower median lymphocyte and platelet counts, albumin and sodium levels, and higher median levels of C-reactive protein, procalcitonin, ferritin, D-dimers, triglycerides, serum creatinine, urea, and γ-glutamyl transpeptidase, and neutrophil count. Multivariate analysis showed that higher procalcitonin, ferritin, and fibrinogen levels at admission were predictive of MAS. Only elevated troponin level was a factor indicating a requirement of PICU hospitalization for children with MAS. MIS-C patients fulfilling MAS criteria were treated more often with intravenous immunoglobulins and steroids than children without MAS. Children with MAS more often required mechanical ventilation. None of the patients required biological agents.

CONCLUSIONS

The clinical course of MAS in MIS-C seems milder, treatment less aggressive, and the prognosis better than expected based on the current knowledge on MAS complicating other rheumatological diseases.

Thrombosis of the right iliac, femoral, popliteal, and tibial arteries in a post-COVID-19 in adolescent

Background

Viral infection into lung, muscular, and endothelial cells results in inflammatory response, including edema, degeneration, and necrotic alterations. The involvement of the major arteries in adolescent with COVID-19 has been infrequently reported in the literature. The aim of the present study is to report thrombosis of the right iliac, femoral and tibial arteries and stenosis of left iliac artery in an adolescent with COVID-19 and to discuss the pathophysiological hypotheses.

Case presentation

We report the case of a 17-year-old female patient with COVID-19 infection. She was seen at the physician specialized general medicine in her hometown, was diagnosed with COVID-19 but did not require hospitalization. After 15 days, she had sudden pain in the left leg that has limited her ability to walk more than 10 met, associated with extremity cyanosis and coldness. Angiotomography revealed thrombosis of a portion of the iliac and popliteal arteries. Na emergency embolectomy was successfully performed, followed by full-dose heparinization with unfractionated heparin.

Conclusion

Arterial thrombosis of large arteries may be associated with chronic inflammatory syndrome secondary to COVID-19 infection and the treatment with a late embolectomy was successful, even in a thrombotic event.

Combined presentation of severe pulmonary COVID-19 and multisystem inflammatory syndrome in children (MIS-C): two reported Egyptian pediatric cases

Background

Initial reports from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic described children as being less susceptible to coronavirus disease (COVID-19) than adults. Later on, a severe and novel pediatric disorder termed multisystem inflammatory syndrome in children (MIS-C) emerged. Pediatric patients with SARS-CoV-2 are at risk for critical illness with severe pulmonary COVID-19 and MIS-C. Both are described as two distinct conditions, and the differentiation between them was the scope of many studies. In this report from Egypt, we will describe two unique pediatric cases presented by combined manifestations of severe pulmonary COVID-19 and MIS-C.

Case presentation

Two patients presented with severe pulmonary COVID-19 evident by pulmonary symptoms, signs, and advanced CO-RADS stage in lung CT were simultaneously fulfilling the clinical criteria of MIS-C including fever, multi-system affection, increased inflammatory markers in addition to the proved COVID-19 by positive serologic tests for SARS-CoV-2 but PCR was negative. Both patients responded well to immune-modulation therapy by IVIG and steroids and discharged well under closed follow-up.

Conclusions

Although it is debatable to present simultaneously, MIS-C should be considered in patients presenting with typical clinical findings and concerns for pulmonary COVID-19 once the criteria for MIS-C diagnosis is fulfilled. Starting treatment without delay can favor better prognosis.

Mining of linear B cell epitopes of SARS-CoV-2 ORF8 protein from COVID-19 patients

Given the on-going SARS-CoV-2 pandemic, identification of immunogenic targets against the viral protein will provide crucial advances towards the development of sensitive diagnostic tools and vaccination strategies. Our previous study has found that ORF8 protein of SARS-CoV-2 is highly immunogenic and shows high sensitivity in identifying COVID-19 disease. In this study, by employing overlapping linear peptides, we characterized the IgG immunodominant regions on SARS-CoV-2 ORF8 protein that are seropositive in the sera from SARS-CoV-2-infected patients. The major immunogenic epitopes are localized at (1) N-termini alpha helix, (2) the resides spanning beta 2 and 3 sheets, and (3) the loop between beta 4 and 5 sheets. Additionally, hamster model infected by SARS-CoV-2 further validates the seropositivity of the linear epitopes in vivo, demonstrating a potential application of the linear peptide-based immunization strategy. Taken together, identification and validation of these B-cell linear epitopes will provide insights into the design of serological diagnostics and peptide-based vaccination approach against this pandemic virus of high priority.

COVID-19 Mechanisms in the Human Body-What We Know So Far

More than one and a half years have elapsed since the commencement of the coronavirus disease 2019 (COVID-19) pandemic, and the world is struggling to contain it. Being caused by a previously unknown virus, in the initial period, there had been an extreme paucity of knowledge about the disease mechanisms, which hampered preventive and therapeutic measures against COVID-19. In an endeavor to understand the pathogenic mechanisms, extensive experimental studies have been conducted across the globe involving cell culture-based experiments, human tissue organoids, and animal models, targeted to various aspects of the disease, viz., viral properties, tissue tropism and organ-specific pathogenesis, involvement of physiological systems, and the human immune response against the infection. The vastly accumulated scientific knowledge on all aspects of COVID-19 has currently changed the scenario from great despair to hope. Even though spectacular progress has been made in all of these aspects, multiple knowledge gaps are remaining that need to be addressed in future studies. Moreover, multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have emerged across the globe since the onset of the first COVID-19 wave, with seemingly greater transmissibility/virulence and immune escape capabilities than the wild-type strain. In this review, we narrate the progress made since the commencement of the pandemic regarding the knowledge on COVID-19 mechanisms in the human body, including virus-host interactions, pulmonary and other systemic manifestations, immunological dysregulations, complications, host-specific vulnerability, and long-term health consequences in the survivors. Additionally, we provide a brief review of the current evidence explaining molecular mechanisms imparting greater transmissibility and virulence and immune escape capabilities to the emerging SARS-CoV-2 variants.

Host Genetics and Antiviral Immune Responses in Adult Patients With Multisystem Inflammatory Syndrome

COVID-19 associated multisystem inflammatory syndrome (MIS) is a rare condition mostly affecting children but also adults (MIS-A). Although severe systemic inflammation and multiorgan dysfunction are hallmarks of the syndrome, the underlying pathogenesis is unclear. We aimed to provide novel immunological and genetic descriptions of MIS-A patients. Cytokine responses (IL-6, IL-1β, TNFα, CXCL10, type I, II and III interferons) following SARS-CoV-2 infection of peripheral blood mononuclear cells in vitro were analyzed as well as antibodies against IFNα and IFNω (by ELISA) in patients and healthy controls. We also performed whole exome sequencing (WES) of patient DNA. A total of five patients (ages 19, 23, 33, 38, 50 years) were included. The patients shared characteristic features, although organ involvement and the time course of disease varied slightly. SARS-CoV-2 in vitro infection of patient PBMCs revealed impaired type I and III interferon responses and reduced CXCL10 expression, whereas production of proinflammatory cytokines were less affected, compared to healthy controls. Presence of interferon autoantibodies was not detected. Whole exome sequencing analysis of patient DNA revealed 12 rare potentially disease-causing variants in genes related to autophagy, classical Kawasaki disease, restriction factors and immune responses. In conclusion, we observed an impaired production of type I and III interferons in response to SARS-CoV-2 infection and detected several rare potentially disease-causing gene variants potentially contributing to MIS-A.

Single-cell RNA sequencing of peripheral blood mononuclear cells from acute Kawasaki disease patients

Kawasaki disease (KD) is the most common cause of acquired heart disease in children in developed countries. Although functional and phenotypic changes of immune cells have been reported, a global understanding of immune responses underlying acute KD is unclear. Here, using single-cell RNA sequencing, we profile peripheral blood mononuclear cells from seven patients with acute KD before and after intravenous immunoglobulin therapy and from three age-matched healthy controls. The most differentially expressed genes are identified in monocytes, with high expression of pro-inflammatory mediators, immunoglobulin receptors and low expression of MHC class II genes in acute KD. Single-cell RNA sequencing and flow cytometry analyses, of cells from an additional 16 KD patients, show that although the percentage of total B cells is substantially decreased after therapy, the percentage of plasma cells among the B cells is significantly increased. The percentage of CD8+ T cells is decreased in acute KD, notably effector memory CD8+ T cells compared with healthy controls. Oligoclonal expansions of both B cell receptors and T cell receptors are observed after therapy. We identify biological processes potentially underlying the changes of each cell type. The single-cell landscape of both innate and adaptive immune responses provides insights into pathogenesis and therapy of KD.

Kidney involvement in multisystem inflammatory syndrome in children: a pediatric nephrologist's perspective

The initial report of the multisystem inflammatory syndrome in children (MIS-C) was from the UK in April 2020; since then, cases have been reported worldwide. Renal involvement has been seen commonly, ranging from 10% to 46%. Kidney involvement following severe acute respiratory syndrome coronavirus 2 infection in children with MIS-C is more common than initially thought and is associated with higher morbidity and mortality. There are several reports of a direct viral tropism of coronavirus disease 2019 and MIS-C-associated renal damage. This study’s objective was to systematically review the current understanding of kidney involvement in children suffering from MIS-C. Based on our systemic literature search, 19 studies have either partially or fully discussed kidney involvement in MIS-C patients. Furthermore, we discuss the multifactorial pathogenesis contributing to acute kidney injury (AKI) development in MIS-C. The current review gives a pediatric nephrologist’s perspective of the renal involvement in MIS-C, the incidence of AKI, the pathophysiology of AKI in MIS-C and the proposed therapeutic regimens available, including the need for kidney replacement therapy for a child with AKI associated with MIS-C. As the disease is rapidly evolving, more detailed clinical prospective studies are required to understand MIS-C and its role in AKI better.

SARS-CoV-2 and the Brain: What Do We Know about the Causality of 'Cognitive COVID?

The second year of the COVID-19 (coronavirus disease) pandemic has seen the need to identify and assess the long-term consequences of a SARS-CoV-2 infection on an individual's overall wellbeing, including adequate cognitive functioning. 'Cognitive COVID' is an informal term coined to interchangeably refer to acute changes in cognition during COVID-19 and/or cognitive sequelae with various deficits following the infection. These may manifest as altered levels of consciousness, encephalopathy-like symptoms, delirium, and loss of various memory domains. Dysexecutive syndrome is a peculiar manifestation of 'Cognitive COVID' as well. In the previous major outbreaks of viruses like SARS-CoV, MERS-CoV and Influenza. There have been attempts to understand the underlying mechanisms describing the causality of similar symptoms following SARS-CoV-2 infection. This review, therefore, is attempting to highlight the current understanding of the various direct and indirect mechanisms, focusing on the role of neurotropism of SARS-CoV-2, the general pro-inflammatory state, and the pandemic-associated psychosocial stressors in the causality of 'Cognitive COVID.' Neurotropism is associated with various mechanisms including retrograde neuronal transmission via olfactory pathway, a general hematogenous spread, and the virus using immune cells as vectors. The high amounts of inflammation caused by COVID-19, compounded with potential intubation, are associated with a deleterious effect on the cognition as well. Finally, the pandemic's unique psychosocial impact has raised alarm due to its possible effect on cognition. Furthermore, with surfacing reports of post-COVID-vaccination cognitive impairments after vaccines containing mRNA encoding for spike glycoprotein of SARS-CoV-2, we hypothesize their causality and ways to mitigate the risk. The potential impact on the quality of life of an individual and the fact that even a minor proportion of COVID-19 cases developing cognitive impairment could be a significant burden on already overwhelmed healthcare systems across the world make it vital to gather further evidence regarding the prevalence, presentation, correlations, and causality of these events and reevaluate our approach to accommodate early identification, management, and rehabilitation of patients exhibiting cognitive symptoms.

Multisystem inflammatory syndrome in children is driven by zonulin-dependent loss of gut mucosal barrier

BACKGROUNDWeeks after SARS-CoV-2 infection or exposure, some children develop a severe, life-threatening illness called multisystem inflammatory syndrome in children (MIS-C). Gastrointestinal (GI) symptoms are common in patients with MIS-C, and a severe hyperinflammatory response ensues with potential for cardiac complications. The cause of MIS-C has not been identified to date.METHODSHere, we analyzed biospecimens from 100 children: 19 with MIS-C, 26 with acute COVID-19, and 55 controls. Stools were assessed for SARS-CoV-2 by reverse transcription PCR (RT-PCR), and plasma was examined for markers of breakdown of mucosal barrier integrity, including zonulin. Ultrasensitive antigen detection was used to probe for SARS-CoV-2 antigenemia in plasma, and immune responses were characterized. As a proof of concept, we treated a patient with MIS-C with larazotide, a zonulin antagonist, and monitored the effect on antigenemia and the patient's clinical response.RESULTSWe showed that in children with MIS-C, a prolonged presence of SARS-CoV-2 in the GI tract led to the release of zonulin, a biomarker of intestinal permeability, with subsequent trafficking of SARS-CoV-2 antigens into the bloodstream, leading to hyperinflammation. The patient with MIS-C treated with larazotide had a coinciding decrease in plasma SARS-CoV-2 spike antigen levels and inflammatory markers and a resultant clinical improvement above that achieved with currently available treatments.CONCLUSIONThese mechanistic data on MIS-C pathogenesis provide insight into targets for diagnosing, treating, and preventing MIS-C, which are urgently needed for this increasingly common severe COVID-19-related disease in children.

Multisystem Inflammatory Syndrome in Children and Adolescents (MIS-C) under the Setting of COVID-19: A Review of Clinical Presentation, Workup and Management

Earlier in its course, SARS-CoV-2 was primarily identified to cause an acute respiratory illness in adults, the elderly and immunocompromised, while children were known to be afflicted with milder symptoms. However, since mid-April of 2020, latent effects of the virus have begun emerging in children and adolescents, which is characterised by a multisystem hyperinflammatory state; thus, the term Multisystem Inflammatory Syndrome in Children (MIS-C) was introduced by the WHO and CDC. The syndrome manifests itself approximately 4 weeks after COVID-19 infection, with symptoms mimicking Kawasaki Disease and Kawasaki Disease Shock Syndrome. Demographically, MIS-C peaks in children aged 5 to 14 years, with clusters in Europe, North and Latin America seen, later followed by Asia. Although the exact pathophysiology behind the syndrome is unknown, recent studies have proposed a post-infectious immune aetiology, which explains the increased levels of immunoglobulins seen in affected patients. Patient presentation includes, but is not limited to, persistent fever, rash, gastrointestinal symptoms and cardiac complications including myocarditis. These patients also have raised inflammatory markers including C reactive protein, ferritin and interleukin-6. In poorly controlled patients, the syndrome can lead to multiorgan failure and death. The mainstay of treatment includes the use of intravenous immunoglobulins, steroids, immune modulators and aspirin. Adjunct therapy includes the use of low molecular weight heparin or warfarin for long term anticoagulation. Currently very little is known about the syndrome, highlighting the need for awareness amongst healthcare workers and parents. Moreover, with increased cases of COVID-19 as a result of the second wave, it is essential to keep MIS-C in mind when attending patients with a past history of COVID-19 exposure or infection. Additionally, once these patients have been identified and treated, strict follow-up must be done in order carry out long term studies, and to identify possible sequelae and complications.

Multisystem inflammatory syndrome in children with COVID-19

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a dangerous pediatric complication of COVID-19.

OBJECTIVE

The purpose of this review article is to provide a summary of the diagnosis and management of MIS-C with a focus on management in the acute care setting.

DISCUSSION

MIS-C is an inflammatory syndrome which can affect nearly any organ system. The most common symptoms are fever and gastrointestinal symptoms, though neurologic and dermatologic findings are also well-described. The diagnosis includes a combination of clinical and laboratory testing. Patients with MIS-C will often have elevated inflammatory markers and may have an abnormal electrocardiogram or echocardiogram. Initial treatment involves resuscitation with careful assessment for cardiac versus vasodilatory shock using point-of-care ultrasound. Treatment should include intravenous immunoglobulin, anticoagulation, and consideration of corticosteroids. Interleukin-1 and/or interleukin-6 blockade may be considered for refractory cases. Aspirin is recommended if there is thrombocytosis or Kawasaki disease-like features on echocardiogram. Patients will generally require admission to an intensive care unit.

CONCLUSION

MIS-C is a condition associated with morbidity and mortality that is increasingly recognized as a potential complication in pediatric patients with COVID-19. It is important for emergency clinicians to know how to diagnose and treat this disorder.

Endothelial Dysfunction as a Component of Severe Acute Respiratory Syndrome Coronavirus 2-Related Multisystem Inflammatory Syndrome in Children With Shock

Supplemental Digital Content is available in the text.

NCT04420468.

Coronavirus disease 2019 respiratory disease in children: clinical presentation and pathophysiology

PURPOSE OF REVIEW

Pediatric coronavirus disease 2019 (COVID-19) respiratory disease is a distinct entity from adult illness, most notable in its milder phenotype. This review summarizes the current knowledge of the clinical patterns, cellular pathophysiology, and epidemiology of COVID-19 respiratory disease in children with specific attention toward factors that account for the maturation-related differences in disease severity.

RECENT FINDINGS

Over the past 14 months, knowledge of the clinical presentation and pathophysiology of COVID-19 pneumonia has rapidly expanded. The decreased disease severity of COVID-19 pneumonia in children was an early observation. Differences in the efficiency of viral cell entry and timing of immune recognition and response between children and adults remain at the center of ongoing research.

SUMMARY

The clinical spectrum of COVID-19 respiratory disease in children is well defined. The age-related differences protecting children from severe disease and death remain incompletely understood.

Multisystem inflammatory syndrome in children and adults (MIS-C/A): Case definition & guidelines for data collection, analysis, and presentation of immunization safety data

This is a Brighton Collaboration Case Definition of the term "Multisystem Inflammatory Syndrome in Children and Adults (MIS-C/A)" to be utilized in the evaluation of adverse events following immunization. The case definition was developed by topic experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of active development of vaccines for SARS-CoV-2. The format of the Brighton Collaboration was followed, including an exhaustive review of the literature, to develop a consensus definition and defined levels of certainty. The document underwent peer review by the Brighton Collaboration Network and by selected expert external reviewers prior to submission. The comments of the reviewers were taken into consideration and edits incorporated into this final manuscript.

Clinical features and outcome of MIS-C patients: an experience from Central Anatolia

Background

Multisystem inflammatory syndrome in children (MIS-C) is a new clinical condition characterized by signs of inflammation and multiorgan dysfunction due to cytokine storm associated with SARS-CoV-2. The clinical spectrum of MIS-C ranges from mild to severe, and even to mortal multisystem involvement. To guide clinicians, we evaluated detailed demographic characteristics, clinical features, laboratory findings, and outcomes of MIS-C cases.

Methods

We performed a retrospective study of patients with MIS-C who were managed in the Department of Pediatric Infectious Disease in the Selcuk University Faculty of Medicine, Konya, Turkey. MIS-C patients were divided into three clinical severity groups (mild, moderate, and severe) and separated into three age groups (< 5 years, 5–10 years, > 10 years). We compared the characteristics of MIS-C cases according to the severity of the disease and by age groups.

Result

Thirty-six children with MIS-C were evaluated (52.8% male, median age of 7.8 years). A clinical spectrum overlapping with Kawasaki disease (KD) was the most common presentation (69.4%) in all age groups. The most common clinical symptoms were fever (100%), mucocutaneous rash (69.4%), and gastrointestinal symptoms (66.6%). There was no statistically significant difference in echocardiographic abnormality between KD-like and the other clinical spectra (p > 0.05). All life-threatening rhythm disturbances were observed in severe cases. No patients died.

Conclusion

It is important to increase the awareness of physicians about the MIS-C disease, which can present with different combinations of different systemic findings, so that patients can be diagnosed and treated in a timely manner.

Key Points • A single tertiary centre study shows that children with MIS-C can present with different clinic spectra other than Kawasaki diseases. • Electrocardiographic and echocardiographic evaluation is important in early diagnosis of children with MIS-C. • Pro-BNP can be used as a screening test in the emergency room for children with prolonged and unexplained fever for determine early cardiac involvement of MIS-C. • The lack of require biological agents and favourable outcomes in children with MIS-C may be related with administration of steroid therapy with IVIG in early stage of disease.

Cell-Type Apoptosis in Lung during SARS-CoV-2 Infection

The SARS-CoV-2 pandemic has inspired renewed interest in understanding the fundamental pathology of acute respiratory distress syndrome (ARDS) following infection. However, the pathogenesis of ARDS following SRAS-CoV-2 infection remains largely unknown. In the present study, we examined apoptosis in postmortem lung sections from COVID-19 patients and in lung tissues from a non-human primate model of SARS-CoV-2 infection, in a cell-type manner, including type 1 and 2 alveolar cells and vascular endothelial cells (ECs), macrophages, and T cells. Multiple-target immunofluorescence assays and Western blotting suggest both intrinsic and extrinsic apoptotic pathways are activated during SARS-CoV-2 infection. Furthermore, we observed that SARS-CoV-2 fails to induce apoptosis in human bronchial epithelial cells (i.e., BEAS2B cells) and primary human umbilical vein endothelial cells (HUVECs), which are refractory to SARS-CoV-2 infection. However, infection of co-cultured Vero cells and HUVECs or Vero cells and BEAS2B cells with SARS-CoV-2 induced apoptosis in both Vero cells and HUVECs/BEAS2B cells but did not alter the permissiveness of HUVECs or BEAS2B cells to the virus. Post-exposure treatment of the co-culture of Vero cells and HUVECs with a novel non-cyclic nucleotide small molecule EPAC1-specific activator reduced apoptosis in HUVECs. These findings may help to delineate a novel insight into the pathogenesis of ARDS following SARS-CoV-2 infection.

The Challenging Diagnosis of Pediatric Multisystem Inflammatory Syndrome Associated with Sars-Cov-2 Infection-Two Case Reports and Literature Review

Severe acute respiratory coronavirus 2 (SARS-CoV-2) is a novel coronavirus discovered in 2019 that caused the coronavirus disease 2019 (COVID19). During the last year, over 70 million people were infected and more than 1.5 million people died. Despite the tremendous number of people infected, children were less affected and presented milder forms of the disease. A short time after the pandemic was declared, a new hyperinflammatory syndrome resembling Kawasaki disease (KD) was described in children with confirmed or suspected SARS-CoV-2 infection named multisystem inflammatory syndrome in children (MIS-C). The incidence of MIS-C is low and it has a polymorphous clinical presentation, making the diagnosis difficult. Although the incidence is reduced, there is a high risk of cardiovascular complications. In order to raise awareness, we present the cases of two pediatric patients diagnosed with MIS-C in our clinic.

Similarities and differences between the immunopathogenesis of COVID-19-related pediatric multisystem inflammatory syndrome and Kawasaki disease

Multisystem inflammatory syndrome associated with the SARS-CoV-2 pandemic has recently been described in children (MIS-C), partially overlapping with Kawasaki disease (KD). We hypothesized that (a) MIS-C and prepandemic KD cytokine profiles may be unique and justify the clinical differences observed, and (b) SARS-CoV-2-specific immune complexes (ICs) may explain the immunopathology of MIS-C. Seventy-four children were included: 14 with MIS-C, 9 patients positive for SARS-CoV-2 by PCR without MIS-C (COVID), 14 with prepandemic KD, and 37 healthy controls (HCs). Thirty-four circulating cytokines were quantified in pretreatment serum or plasma samples and the presence of circulating SARS-CoV-2 ICs was evaluated in MIS-C patients. Compared with HCs, the MIS-C and KD groups showed most cytokines to be significantly elevated, with IFN-γ-induced response markers (including IFN-γ, IL-18, and IP-10) and inflammatory monocyte activation markers (including MCP-1, IL-1α, and IL-1RA) being the main triggers of inflammation. In linear discriminant analysis, MIS-C and KD profiles overlapped; however, a subgroup of MIS-C patients (MIS-Cplus) differentiated from the remaining MIS-C patients in IFN-γ, IL-18, GM-CSF, RANTES, IP-10, IL-1α, and SDF-1 and incipient signs of macrophage activation syndrome. Circulating SARS-CoV-2 ICs were not detected in MIS-C patients. Our findings suggest a major role for IFN-γ in the pathogenesis of MIS-C, which may be relevant for therapeutic management.

COVID-19 and Pediatric Asthma: Clinical and Management Challenges

Asthma is the most frequent chronic condition in childhood and a current concern exists about asthma in the pediatric population and its risk for severe SARS-CoV-2 infection. Although all ages can be affected, SARS-CoV-2 infection has lower clinical impact on children and adolescents than on adults. Fever, cough and shortness of breath are the most common symptoms and signs in children; wheezing has not been frequently reported. Published studies suggest that children with asthma do not appear to be disproportionately more affected by COVID-19. This hypothesis raises two issues: is asthma (and/or atopy) an independent protective factor for COVID-19? If yes, why? Explanations for this could include the lower IFN-α production, protective role of eosinophils in the airway, and antiviral and immunomodulatory proprieties of inhaled steroids. Additionally, recent evidence supports that allergic sensitization is inversely related to ACE2 expression. Obesity is a known risk factor for COVID-19 in adults. However, in the childhood asthma–obesity phenotype, the classic atopic Th2 pattern seems to predominate, which could hypothetically be a protective factor for severe SARS-CoV-2 infection in children with both conditions. Finally, the return to school activities raises concerns, as asymptomatic children could act as vectors for the spread of the disease. Although this is still a controversial topic, the identification and management of asymptomatic children is an important approach during the SARS-CoV-2 epidemic. Focus on asthma control, risk stratification, and medication adherence will be essential to allow children with asthma to return safely to school.

Pandemics Throughout History

The emergence and spread of infectious diseases with pandemic potential occurred regularly throughout history. Major pandemics and epidemics such as plague, cholera, flu, severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) have already afflicted humanity. The world is now facing the new coronavirus disease 2019 (COVID-19) pandemic. Many infectious diseases leading to pandemics are caused by zoonotic pathogens that were transmitted to humans due to increased contacts with animals through breeding, hunting and global trade activities. The understanding of the mechanisms of transmission of pathogens to humans allowed the establishment of methods to prevent and control infections. During centuries, implementation of public health measures such as isolation, quarantine and border control helped to contain the spread of infectious diseases and maintain the structure of the society. In the absence of pharmaceutical interventions, these containment methods have still been used nowadays to control COVID-19 pandemic. Global surveillance programs of water-borne pathogens, vector-borne diseases and zoonotic spillovers at the animal-human interface are of prime importance to rapidly detect the emergence of infectious threats. Novel technologies for rapid diagnostic testing, contact tracing, drug repurposing, biomarkers of disease severity as well as new platforms for the development and production of vaccines are needed for an effective response in case of pandemics.

The Importance of Early Recognition, Timely Management, and the Role of Healthcare Providers in Multisystem Inflammatory Syndrome in Children

In April 2020, a pediatric report of an unusual inflammatory illness associated with coronavirus disease 2019 (COVID-19) led to similar cases in Europe and North America, which was referred to as multisystem inflammatory syndrome in children (MIS-C). Herein, we describe the case of a 12-year-old boy who had a history of polymerase chain reaction-confirmed COVID-19 and developed MIS-C approximately three weeks after an initial diagnosis of COVID-19. High fever with abdominal pain mimicking appendicitis was the initial manifestation of MIS-C, which could have been easily missed if the patient's history of COVID-19 was ignored. Intravenous immunoglobulin was administered twice, 24 hours apart, five days after the onset of MIS-C, and the patient fully recovered without any obvious sequelae. Early recognition by disease awareness and prompt management are the keys to saving the lives of children affected by MIS-C.

Multisystem Inflammatory Syndrome in Children: Unique Disease or Part of the Kawasaki Disease Spectrum?

One of the most intriguing and mysterious phenomena observed during the COVID-19 pandemic has been represented by the occurrence of the multisystem inflammatory syndrome in children and adolescents (MIS-C). Patients with this condition have some overlapping signs and symptoms with those of Kawasaki disease (KD), but also display clinical features that are uncommon or less frequent in this illness, such as diarrhea, abdominal pain and myocardial involvement. The sickest patients may develop multiorgan failure and shock, usually due to myocarditis. Management is based on the administration of intravenous immunoglobulin, glucocorticoids and, in the most severe instances, anakinra. It is still debated whether MIS-C and KD represent different illnesses or are part of the same disease spectrum. The aim of the present review is to analyze critically the evidence in favor of the latter hypothesis and to provide the authors' personal interpretation of the relationship between the two conditions.

Cell-type apoptosis in lung during SARS-CoV-2 infection

The SARS-CoV-2 pandemic has inspired renewed interest in understanding the fundamental pathology of acute respiratory distress syndrome (ARDS) following infection because fatal COVID-19 cases are commonly linked to respiratory failure due to ARDS. The pathologic alteration known as diffuse alveolar damage in endothelial and epithelial cells is a critical feature of acute lung injury in ARDS. However, the pathogenesis of ARDS following SRAS-CoV-2 infection remains largely unknown. In the present study, we examined apoptosis in post-mortem lung sections from COVID-19 patients and lung tissues from a non-human primate model of SARS-CoV-2 infection, in a cell-type manner, including type 1 and 2 alveolar cells and vascular endothelial cells (ECs), macrophages, and T cells. Multiple-target immunofluorescence (IF) assays and western blotting suggest both intrinsic and extrinsic apoptotic pathways are activated during SARS-CoV-2 infection. Furthermore, we observed that SARS-CoV-2 fails to induce apoptosis in human bronchial epithelial cells (i.e., BEAS2B cells) and primary human umbilical vein endothelial cells (HUVECs), which are refractory to SARS-CoV-2 infection. However, infection of co-cultured Vero cells and HUVECs or Vero cells and BEAS2B cells with SARS-CoV-2 induced apoptosis in both Vero cells and HUVECs/BEAS2B cells, but did not alter the permissiveness of HUVECs or BEAS2B cells to the virus. Post-exposure treatment of the co-culture of Vero cells and HUVECs with an EPAC1-specific activator ameliorated apoptosis in HUVECs. These findings may help to delineate a novel insight into the pathogenesis of ARDS following SARS-CoV-2 infection.

Coronavirus Desease 2019 (COVID-19) in Children: Lessons from Pediatric Rheumatology

The clinical presentation and outcomes of infection with the novel coronavirus (COVID-19) are characterized by exceptional variability in manifestations, which depend on many factors, one of which is the patient’s age. One of the severe life-threatening manifestations in adults is severe acute respiratory syndrome (SARS-CoV-2), in some cases accompanied by the development of multiple organ failure. During the first two to three months of the COVID-19 pandemic, the global medical community was of the opinion that this disease in children is usually mild and not fatal. However, with the accumulation of new information, it became clear that there is a growing recognition of the existence of multisystem inflammatory syndrome in children, chronologically associated with SARS-CoV-2, which can lead to serious consequences. The article presents the main epidemiological, clinical and laboratory characteristics of the syndrome, as well as discusses the issues of its pathogenesis, differential diagnosis with a number of other acute conditions associated with an dysbalance of cytokines.

Deep Immune Profiling of MIS-C demonstrates marked but transient immune activation compared to adult and pediatric COVID-19

Pediatric COVID-19 following SARS-CoV-2 infection is associated with fewer hospitalizations and often milder disease than in adults. A subset of children, however, present with Multisystem Inflammatory Syndrome in Children (MIS-C) that can lead to vascular complications and shock, but rarely death. The immune features of MIS-C compared to pediatric COVID-19 or adult disease remain poorly understood. We analyzed peripheral blood immune responses in hospitalized SARS-CoV-2 infected pediatric patients (pediatric COVID-19) and patients with MIS-C. MIS-C patients had patterns of T cell-biased lymphopenia and T cell activation similar to severely ill adults, and all patients with MIS-C had SARS-CoV-2 spike-specific antibodies at admission. A distinct feature of MIS-C patients was robust activation of vascular patrolling CX3CR1+ CD8 T cells that correlated with use of vasoactive medication. Finally, whereas pediatric COVID-19 patients with acute respiratory distress syndrome (ARDS) had sustained immune activation, MIS-C patients displayed clinical improvement over time, concomitant with decreasing immune activation. Thus, non-MIS-C versus MIS-C SARS-CoV-2 associated illnesses are characterized by divergent immune signatures that are temporally distinct and implicate CD8 T cells in clinical presentation and trajectory of MIS-C.