Multisystem inflammatory syndrome (MIS-C): a systematic review and meta-analysis of clinical characteristics, treatment, and outcomes

Hemolytic uremic syndrome in the setting of COVID-19 successfully treated with complement inhibition therapy: An instructive case report of a previously healthy toddler and review of literature

INTRODUCTION

As the global pandemic continues, new complications of COVID-19 in pediatric population have turned up, one of them being hemolytic uremic syndrome (HUS), a complement-mediated thrombotic microangiopathy (CM-TMA) characterized by triad of thrombocytopenia, microangiopathic hemolytic anemia and acute kidney injury (AKI). With both multisystem inflammatory syndrome in children (MIS-C) and HUS sharing complement dysregulation as one of the key factors, the aim of this case report is to highlight differences between these two conditions and also emphasize the importance of complement blockade as a treatment modality.

CASE REPORT

We describe a 21-month-old toddler who initially presented with fever and confirmed COVID-19. His condition quickly deteriorated and he developed oliguria, accompanied with diarrhea, vomiting and oral intake intolerance. HUS was suspected, supported with compelling laboratory findings, including decreased platelets count and C3 levels, elevated LDH, urea, serum creatinine and sC5b-9 and presence of schistocytes in peripheral blood, negative fecal Shiga toxin and normal ADAMTS13 metalloprotease activity. The patient was given C5 complement blocker Ravulizumab and started to display rapid improvement.

CONCLUSION

Although reports of HUS in the setting of COVID-19 continue to pour in, the questions of exact mechanism and similarities to MIS-C remain. Our case for the first time accentuates the use of complement blockade as a valuable treatment option in this scenario. We sincerely believe that reporting on HUS as a complication of COVID-19 in children will give rise to improved diagnosis and treatment, as well as better understanding of both of these intricating diseases.

The First Case in Japan of Fulminant Myocarditis Due to Multisystem Inflammatory Syndrome in Children (MIS-C) That Required Mechanical Circulatory Support

Multisystem inflammatory syndrome in children (MIS-C) is a novel hyperinflammatory syndrome that is associated with severe acute respiratory syndrome coronavirus 2 infections. Reports describing the mechanical circulatory support (MCS) and myocardial biopsy for fulminant myocarditis due to MIS-C are limited.A 13-year-old male patient with MIS-C underwent treatment, including immunosuppressive therapy and MCS devices, and managed to recover from pulseless electrical activity cardiac arrest.This is the first patient in Japan with MIS-C who required MCS devices in Japan. Appropriate and immediate treatment with immunosuppressive therapy and MCS devices is important.

The Gut Microbiome of Children during the COVID-19 Pandemic

The gut microbiome has been shown to play a critical role in maintaining a healthy state. Dysbiosis of the gut microbiome is involved in modulating disease severity and potentially contributes to long-term outcomes in adults with COVID-19. Due to children having a significantly lower risk of severe illness and limited sample availability, much less is known about the role of the gut microbiome in children with COVID-19. It is well recognized that the developing gut microbiome of children differs from that of adults, but it is unclear if this difference contributes to the different clinical presentations and complications. In this review, we discuss the current knowledge of the gut microbiome in children with COVID-19, with gut microbiome dysbiosis being found in pediatric COVID-19 but specific taxa change often differing from those described in adults. Additionally, we discuss possible mechanisms of how the gut microbiome may mediate the presentation and complications of COVID-19 in children and the potential role for microbial therapeutics.

Gastrointestinal tract lesion in children with COVID-19: from pathogenesis to clinical manifestations

Since the beginning of the pandemic, the new coronavirus infection has been regarded primarily as a respiratory disease. By now, it has become obvious that COVID-19 is a systemic infectious process with multiple organ damage. Having affinity for ACE-2 receptors, the virus can infect the cells of the respiratory tract, as well as the cells of the cardiovascular and nervous systems and smooth muscle structures of various organs. Expression of ACE-2 by enterocytes of the small intestine makes the gastrointestinal tract vulnerable in COVID-19 disease and leads to the manifestation of symptoms of gastrointestinal damage, which is often observed in clinical practice. Gastrointestinal symptoms usually include anorexia, nausea, vomiting, diarrhea, and abdominal pain, which can occur both at the onset and during the disease. Several mechanisms are described to explain these changes in COVID-19. 

Clinical Features and Burden of Postacute Sequelae of SARS-CoV-2 Infection in Children and Adolescents

Importance

The postacute sequelae of SARS-CoV-2 infection (PASC) has emerged as a long-term complication in adults, but current understanding of the clinical presentation of PASC in children is limited.

Objective

To identify diagnosed symptoms, diagnosed health conditions, and medications associated with PASC in children.

Design, Setting and Participants

This retrospective cohort study used electronic health records from 9 US children's hospitals for individuals younger than 21 years who underwent antigen or reverse transcriptase-polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 between March 1, 2020, and October 31, 2021, and had at least 1 encounter in the 3 years before testing.

Exposures

SARS-CoV-2 positivity by viral test (antigen or RT-PCR).

Main Outcomes and Measures

Syndromic (symptoms), systemic (conditions), and medication PASC features were identified in the 28 to 179 days following the initial test date. Adjusted hazard ratios (aHRs) were obtained for 151 clinically predicted PASC features by contrasting viral test-positive groups with viral test-negative groups using proportional hazards models, adjusting for site, age, sex, testing location, race and ethnicity, and time period of cohort entrance. The incidence proportion for any syndromic, systemic, or medication PASC feature was estimated in the 2 groups to obtain a burden of PASC estimate.

Results

Among 659 286 children in the study sample, 348 091 (52.8%) were male, and the mean (SD) age was 8.1 (5.7) years. A total of 59 893 (9.1%) tested positive by viral test for SARS-CoV-2, and 599 393 (90.9%) tested negative. Most were tested in outpatient testing facility settings (322 813 [50.3%]) or office settings (162 138 [24.6%]). The most common syndromic, systemic, and medication features were loss of taste or smell (aHR, 1.96; 95% CI, 1.16-3.32), myocarditis (aHR, 3.10; 95% CI, 1.94-4.96), and cough and cold preparations (aHR, 1.52; 95% CI, 1.18-1.96), respectively. The incidence of at least 1 systemic, syndromic, or medication feature of PASC was 41.9% (95% CI, 41.4-42.4) among viral test-positive children vs 38.2% (95% CI, 38.1-38.4) among viral test-negative children, with an incidence proportion difference of 3.7% (95% CI, 3.2-4.2). A higher strength of association for PASC was identified in those cared for in the intensive care unit during the acute illness phase, children younger than 5 years, and individuals with complex chronic conditions.

Conclusions and Relevance

In this large-scale, exploratory study, the burden of pediatric PASC that presented to health systems was low. Myocarditis was the most commonly diagnosed PASC-associated condition. Acute illness severity, young age, and comorbid complex chronic disease increased the risk of PASC.

COVID-19 and PIMS-Two Different Entities, but the Same Trigger

COVID-19 and PIMS represent two novel pathologies that have challenged the medical world during the last two years on account of their being very similar, but yet very different. Our aim was to comparatively assess children with SARS-CoV-2 infection and PIMS in terms of symptoms, clinical findings, laboratory parameters, echocardiography, and evolution. Our retrospective study included 46 children with COVID-19 (group 1), and 20 children with confirmed PIMS (group 2). We found no significant differences in terms of age, gender, and originating area between the two groups. We noticed that fever was significantly more common in the PIMS group as compared to COVID-19 group (p = 0.0217). In terms of laboratory parameters, increased bilirubin and creatinine were significantly more frequent in children with COVID-19 (p = 0.0064/p = 0.0064), while hypoalbuminemia and elevated ESR were significantly more common in those with PIMS (p < 0.0001/p = 0.0127). Moreover, prognosis parameters such as D-dimers, NT-proBNP, and CK-MB were also found to be significantly higher in the PIMS group as compared to COVID-19 group (p = 0.0003/p = 0.0182/p = 0.0007). In terms of complications, most were identified in PIMS group, among which cardiac and liver impairment along with dehydration were significantly more common in children diagnosed with PIMS as compared to those detected with COVID-19. Similarly, children with PIMS had a significantly higher chance to have pathological echocardiography changes. Although difficult, the distinction between COVID-19 and PIMS is crucial for the patient’s long-term outcome.

SARS-CoV-2 variants and the risk of pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 among children in Germany

Purpose

To investigate the relationship between the risk of pediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) in children and the predominance of different SARS-CoV-2 variants of concern (VOC) over time.

Methods

In relation to the Alpha, Delta, and Omicron VOC phases of the pandemic, the risk of developing PIMS-TS was calculated by analyzing data for rtPCR-confirmed SARS-CoV-2 infections reported to the German statutory notification system, along with data captured by a separate, national PIMS-TS registry. Both overall infection rates and age group-specific ratios of PIMS-TS during the different pandemic phases were calculated using the Alpha period as the baseline.

Results

The PIMS-TS rate changed significantly over time. When the Alpha VOC was dominant [calendar week (CW) 11 in March–CW 31 in August 2021], the PIMS-TS rate was 6.19 [95% confidence intervals (95% CI) 5.17, 7.20]. When Delta prevailed (CW 32 in August 2021–CW 4 in January 2022), the rate decreased to 1.68 (95% CI 1.49, 1.87). During the Omicron phase (CW 5 in January–CW 16 in April 2022), the rate fell further to 0.89 (95% CI 0.79, 1.00). These changes correspond to a decreased PIMS-TS rate of 73% (rate ratio 0.271, 95% CI 0.222; 0.332) and 86% (rate ratio 0.048, 95% CI 0.037; 0.062), respectively, in comparison to the Alpha period. Rate ratios were nearly identical for all age groups.

Conclusion

The data strongly suggest an association between the risk for PIMS-TS and the prevailing VOC, with highest risk related to Alpha and the lowest to Omicron. Given the uniformity of the decreased risk across age groups, vaccination against SARS-CoV-2 does not appear to have a significant impact on the risk of children developing PIMS-TS.

Clinico-Laboratory Profile, Intensive Care Needs and Short-Term Outcome of Multisystem Inflammatory Syndrome in Children (MIS-C): Experience during First and Second Waves from North India

OBJECTIVES

To describe the clinico-laboratory profile, intensive care needs and outcome of multisystem inflammatory syndrome in children (MIS-C) during the first and second waves.

METHODOLOGY

This retrospective study was conducted in the paediatric emergency and paediatric intensive care unit (PICU) of a tertiary care teaching hospital in North India involving 122 children with MIS-C admitted during the first wave (September 2020-January 2021, n = 40) and second wave (February 2021-September 2021, n = 82) of coronavirus disease 2019 (COVID-19).

RESULTS

The median (interquartile range) age was 7 (4-10) years and 67% were boys. Common manifestations included fever (99%), abdominal symptoms (81%), rash (66%) and conjunctival injection (65%). Elevated C-reactive protein (97%), D-dimer (89%), procalcitonin (80%), IL-6 (78%), ferritin (56%), N-terminal pro B-type natriuretic peptide (84%) and positive severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibody (81%) were common laboratory abnormalities. Cardiovascular manifestations included myocardial dysfunction (55%), shock (48%) and coronary artery changes (10%). The treatment included intensive care support (57%), non-invasive (33%) and invasive (18%) ventilation, vasoactive drugs (47%), intravenous immunoglobulin (IVIG) (83%), steroids (85%) and aspirin (87%). The mortality was 5% (n = 6). During the second wave, a significantly higher proportion had positive SARS-CoV-2 antibody, contact with COVID-19 and oral mucosal changes; lower markers of inflammation; lower proportion had lymphopenia, elevated IL-6 and ferritin; lower rates of shock, myocardial dysfunction and coronary artery changes; lesser need of PICU admission, fluid boluses, vasoactive drugs and IVIG; and shorter hospital stay.

CONCLUSION

MIS-C is a febrile multisystemic disease characterized by hyperinflammation, cardiovascular involvement, temporal relationship to SARS-CoV-2 and good outcome with immunomodulation and intensive care. During the second wave, the severity of illness, degree of inflammation, intensive care needs, and requirement of immunomodulation were less as compared to the first wave.

COVID‐19‐associated secondary hemophagocytic lymphohistiocytosis requiring hematopoietic cell transplant

Coronavirus disease 2019 (COVID‐19) infection causes a variety of extrapulmonary complications in pediatric patients. Multisystem inflammatory syndrome and hemophagocytic lymphohistiocytosis (HLH) are related to hypercytokinemia in COVID‐19 patients. HLH is a disorder of exaggerated inflammation resulting in a cytokine storm and unrestricted hemophagocytosis. HLH can be primary (familial) or secondary (acquired). Secondary HLH (sHLH) can occur in patients with rheumatologic, oncologic, or infectious diseases. The link between COVID‐19 and HLH has been reported in pediatric patients. Here we report a case of a pediatric patient who developed refractory sHLH secondary to COVID‐19 infection and required a hematopoietic cell transplant for the cure.

Clinical features and burden of post-acute sequelae of SARS-CoV-2 infection in children and adolescents: an exploratory EHR-based cohort study from the RECOVER program

Importance

The post-acute sequelae of SARS-CoV-2 (PASC) has emerged as a long-term complication in adults, but current understanding of the clinical presentation of PASC in children is limited.

Objective

To identify diagnosed symptoms, diagnosed health conditions and medications associated with PASC in children.

Design Setting and Participants

Retrospective cohort study using electronic health records from 9 US children's hospitals for individuals <21 years-old who underwent reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 between March 1, 2020 - October 31, 2021 and had at least 1 encounter in the 3 years before testing.

Exposure

SARS-CoV-2 PCR positivity.

Main Outcomes and Measures

We identified syndromic (symptoms), systemic (conditions), and medication PASC features in the 28-179 days following the initial test date. Adjusted hazard ratios (aHRs) were obtained for 151 clinically predicted PASC features by contrasting PCR-positive with PCR-negative groups using proportional hazards models, adjusting for site, age, sex, testing location, race/ethnicity, and time-period of cohort entrance. We estimated the incidence proportion for any syndromic, systemic or medication PASC feature in the two groups to obtain a burden of PASC estimate.

Results

Among 659,286 children in the study sample, 59,893 (9.1%) tested positive by PCR for SARS-CoV-2. Most were tested in outpatient testing facility (50.3%) or office (24.6%) settings. The most common syndromic, systemic, and medication features were loss of taste or smell (aHR 1.96 [95% CI 1.16-3.32), myocarditis (aHR 3.10 [95% CI 1.94-4.96]), and cough and cold preparations (aHR 1.52 [95% CI 1.18-1.96]). The incidence of at least one systemic/syndromic/medication feature of PASC was 41.9% among PCR-positive children versus 38.2% among PCR-negative children, with an incidence proportion difference of 3.7% (95% CI 3.2-4.2%). A higher strength of association for PASC was identified in those cared for in the ICU during the acute illness phase, children less than 5 years-old, and individuals with complex chronic conditions.

Conclusions and Relevance

In this large-scale, exploratory study, the burden of pediatric PASC that presented to health systems was low. Myocarditis was the most commonly diagnosed PASC-associated condition. Acute illness severity, young age, and comorbid complex chronic disease increased the risk of PASC.

Key Points

Question: What are the incidence and clinical features of post-acute sequelae of SARS-CoV-2 infection (PASC) in children?Findings: In this retrospective cohort study of 659,286 children tested for SARS-CoV-2 by polymerase chain reaction (PCR), the symptom, condition and medication with the strongest associations with SARS-CoV-2 infection were loss of taste/smell, myocarditis, and cough and cold preparations. The incidence proportion of non-MIS-C related PASC in the PCR-positive group exceeded the PCR-negative group by 3.7% (95% CI 3.2-4.2), with increased rates associated with acute illness severity, young age, and medical complexity.Meaning: PASC in children appears to be uncommon, with features that differ from adults.

Reversible Autoimmune Cardiomyopathy Secondary to a Vaccine-Induced Multisystem Inflammatory Syndrome

The Dominican government started an early booster protocol, including a heterogeneous vaccination sequence needed based on availability. We report a case of a 25-year-old male who presented with jaundice, and vomiting for 6 days, associated with maculopapular rash (Mucocutaneous features), elevated pro-B-type natriuretic peptide (pro-BNP), erythrocyte sedimentation rate (ESR), transaminitis (> 1000 U/L), thrombocytopenia, echocardiogram evidenced stigmata of heart failure after his third dose of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. He was started on steroids and immunoglobulin therapy for multisystemic organ failure syndrome. A significant improvement was noticed, then was discharge; in the post-discharge clinic, he was asymptomatic, inflammatory markers improved, and the echocardiogram showed a recovered ejection fraction. An accurate anamnesis, including a proper chronologic gathering of the events, is essential to recognize a vaccine-multisystem inflammatory syndrome; its prompt assessment and therapy would directly improve the outcome.

Is It Inflammatory Bowel Disease Flare or Pediatric Inflammatory Multisystem Syndrome Temporally Associated with COVID-19?

Pediatric inflammatory multisystem syndrome temporally associated with COVID-19/multi-system inflammatory syndrome in children (PIMS-TS/MIS-C) is a potentially life-threatening complication of SARS-CoV-2 infection in children. Gastrointestinal manifestations are prominent in children with PIMS-TS/MIS-C. Thus, it is challenging to differentiate this condition from an exacerbation of inflammatory bowel disease (IBD). We aimed to present the clinical characteristics, and diagnostic and therapeutic difficulties in patients with overlapping IBD and PIMS-TS/MIS-C; Methods: We reviewed medical records of children hospitalized due to overlapping IBD and PIMS-TS/MIS-C in a single pediatric hospital from December 2020 to December 2021; Results: There were four children with overlapping IBD flare and PIMS-TS/MIS-C. In three cases, IBD recognition preceded PIMS-TS/MIS-C onset and PIMS-TS/MIS-C occurred during anti-inflammatory therapy of IBD. All children presented with gastrointestinal symptoms at PIMS-TS/MIS-C onset. All patients received IVIG and ASA treatment. In three children there was a need to use steroids to resolve PIMS-TS/MIS-C symptoms. One child was vaccinated against COVID-19; Conclusions: SARS-CoV-2 infection may affect patients with underlying inflammatory conditions such as IBD, inducing systemic symptoms of PIMS-TS/MIS-C, and probably triggering IBD after PIMS-TS/MIS-C. The resemblance of clinical presentations is the main source of diagnostic and therapeutic challenges in PIMS-TS/MIS-C in patients with underlying IBD.

Comparison of Laboratory Data between Children with Kawasaki Disease and COVID-19

Background: Coronavirus disease 2019 (COVID-19) has been an emerging, rapidly evolving situation in China since late 2019 and has even become a worldwide pandemic. The first case of severe childhood novel coronavirus pneumonia in China was reported in March 2020 in Wuhan. The severity differs between adults and children, with lower death rates and decreased severity for individuals under the age of 20 years. Increased cases of Kawasaki disease (KD) have been reported from New York City and some areas of Italy and the U.K., with almost a 6–10 times increase when compared to previous years. We conducted this study to compare characteristics and laboratory data between KD and COVID-19 in children. Methods: We obtained a total of 24 children with COVID-19 from a literature review and 268 KD cases from our hospital via retrospective chart review. Results: We found that patients with KD have higher levels of white blood cells (WBCs), platelets, neutrophil percentage, C-reactive protein (CRP), procalcitonin, and aspartate aminotransferase (AST) and a higher body temperature, while patients with COVID-19 have a higher age, hemoglobin levels, and lymphocyte percentage. After performing multiple logistic regression analysis, we found that age, WBCs, platelets, procalcitonin, and AST are identical markers for distinguishing COVID-19 from KD in children. Conclusion: In this COVID-19 pandemic period, clinicians should pay attention to children with COVID-19 infection when high WBC, platelet, procalcitonin, and AST values are present in order to provide early diagnosis for KD or multisystem inflammatory syndrome in children (MIS-C).

Multisystem Inflammatory Syndrome and Autoimmune Diseases Following COVID-19: Molecular Mechanisms and Therapeutic Opportunities

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), has led to huge concern worldwide. Some SARS-CoV-2 infected patients may experience post–COVID-19 complications such as multisystem inflammatory syndrome, defined by symptoms including fever and elevated inflammatory markers (such as elevation of C reactive protein (CRP), erythrocyte sedimentation rate, fibrinogen, procalcitonin test, D-dimer, ferritin, lactate dehydrogenase or IL-6, presence of neutrophilia, lymphopenia, decreased albumin, and multiple organ dysfunction). Post–COVID-19 complications may also manifest as autoimmune diseases such as Guillain-Barré syndrome and systemic lupus erythematosus. Signaling disorders, increased inflammatory cytokines secretion, corticosteroid use to treat COVID-19 patients, or impaired immune responses are suggested causes of autoimmune diseases in these patients. In this review, we discuss the molecular and pathophysiological mechanisms and therapeutic opportunities for multisystem inflammatory syndrome and autoimmune diseases following SARS-CoV-2 infection with the aim to provide a clear view for health care providers and researchers.

Multisystem inflammatory syndrome in a child with low inflammatory markers, persistent hyponatremia, and natriuresis

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) is a rare complication after infection with Coronavirus disease 2019 (COVID-19), and the differential diagnosis from Kawasaki disease is predominantly based on patients' older age and positive anti-SARS-CoV-2 antibodies in most cases.

CASE DESCRIPTION

We report an "atypical" case of MIS-C in a 3.5-year-old child, with relatively low levels of inflammatory markers, persistent hyponatremia, and hypoalbuminemia, along with exceptionally high levels of brain natriuretic peptide (BNP) and myocardial dysfunction. Persistent hyponatremia was mainly related to natriuresis, while BNP elevation was a marker of the disease severity, reflecting abnormal cardiac function.

CONCLUSION

Low inflammatory markers in children under the age of five years should not exclude a possible diagnosis of MIS-C. HIPPOKRATIA 2022, 26 (2):83-85.