Multisystem Inflammatory Syndrome in Children - A New Syndrome Complicated With Acute Heart Failure Following Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection

Nationwide Survey of Multisystem Inflammatory Syndrome in Children Associated with Coronavirus Disease 2019 in Japan

BACKGROUND

Multisystem inflammatory syndrome in children (MIS-C) presents some clinical overlap with Kawasaki disease (KD). Although KD is common in Japan, the clinical characteristics of MIS-C in Japan remain unknown. Therefore, we aimed to determine the epidemiological and clinical features of MIS-C in Japan.

METHODS

Using a case reporting form, a nationwide registry was created between November 2020 and March 2023, involving 2,080 facilities throughout Japan. We prospectively and retrospectively enrolled patients with MIS-C. The primary outcomes were the number and incidence rates of children with MIS-C. The secondary outcomes included clinical features, such as KD phenotype, organ involvement, shock, intensive care unit admission, and coronary artery lesions.

RESULTS

Among 398 patients registered, central review identified 129 MIS-C cases (mean age: 8·8 ± 3·7 years). The overall incidence rate was estimated to be 1·5 per 100,000 COVID-19 cases, exhibiting a decline as the COVID-19 pandemic progressed, from 12·3 cases (Pre-Delta) to 1·3 cases (Omicron); 80% of MIS-C cases occurred during the Omicron variant predominant period, and 72% of children with MIS-C met the KD criteria. Cardiovascular (88%) and gastrointestinal (90%) involvement were frequent. In Japan, MIS-C cases showed comparatively less severe clinical features, with shock in 29% and admission to the intensive care unit in 12% of cases. Coronary artery lesions were identified in 15 cases (11·6%), irrespective of the presence of shock. No fatalities were reported.

CONCLUSION

The incidence of MIS-C was low in Japan. The clinical features distinctively exhibited a more KD-like phenotype, with less severe clinical features.

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.

Multisystem inflammatory syndrome in children in Singapore

Introduction: Multisystem inflammatory syndrome in children (MIS-C) is a rare inflammatory syndrome with multisystem involvement affecting children exposed to COVID-19. This condition is rarely reported in East Asia and was not detected in Singapore until 2021. We present 12 cases of MIS-C diagnosed in KK Women’s and Children’s Hospital (KKH) from October 2021 to December 2021. Method: We conducted an observational study on cases fulfilling the Singapore Ministry of Health criteria for MIS-C from January 2020 to December 2021 in KKH. Medical records were reviewed to obtain information on clinical presentation, disease course, treatment received and outcomes. Results: In the 12 cases detected, the median age was 7.50 years (interquartile range 4.00–9.25); 8 were male. All patients had mucocutaneous symptoms similar to Kawasaki disease. Other commonly involved systems were: haematological (coagulopathy 100%, lymphopaenia 91.70% and thrombocytopaenia 75.00%), gastrointestinal (75.00%) and cardiovascular (83.30%). Six patients (50.00%) had shock and were admitted to the intensive care unit. The majority of patients received treatment within 2 days of hospitalisation with intravenous immunoglobulin (IVIg) and steroids. All survived; the majority had normal echocardiograms and no long-term organ sequelae at 6 months post-discharge. Conclusion: MIS-C emerged in Singapore as the incidence of COVID-19 in the community increased in 2021. The clinical presentation of our patients is similar to earlier reports, with some significant differences from Kawasaki disease. Multidisciplinary management, timely diagnosis, and early initiation of treatment with IVIg and steroids likely contributed to comparatively good outcomes. Our cases highlight the need for continued awareness of MIS-C among physicians, and surveillance of its incidence, short- and long-term outcomes. Keywords: COVID-19, children, MIS-C, inflammation, paediatrics

Updates on Coronavirus Disease 2019 in Children in Japan

This review provides updates on coronavirus disease 2019 (COVID-19) in children in Japan by summarizing published data. By the end of March 2022, Japan had experienced 6 waves of COVID-19 outbreaks. Over this time, the clinical features presented among children have changed in the context of the predominant variants. Although the COVID-19 pandemic affected children in terms of medical, physical and psychosocial aspects, the clinical outcomes have been favorable in Japan compared with those in some European countries and the United States, which may be partly due to a lower incidence of multisystem inflammatory syndromes in children and obesity. The COVID-19 vaccine has been available for children; however, the vaccination rate in children 5-11 years of age is lower than that in older children due to the government's lack of an active approach in this specific population. Further action is needed to improve the overall vaccination rates in children.

Infliximab treatment for refractory COVID-19-associated multisystem inflammatory syndrome in a Japanese child

Patients with multisystem inflammatory syndrome in children (MIS-C) can develop clinical features resembling Kawasaki disease (KD). A full picture of MIS-C in East Asia which has higher incidence of KD than other regions remains unclear. We report on a 15-year-old Japanese boy with refractory MIS-C who was successfully treated with infliximab. A Japanese boy who was diagnosed with coronavirus disease 2019 (COVID-19) before a month developed MIS-C with fulfilling six principal symptoms of KD. Laboratory data showed extreme hyperferritinemia (11,404 ng/mL), besides lymphopenia and thrombocytopenia. The patient was refractory to initial therapy with intravenous immunoglobulin (IVIG; 2 g/kg), aspirin, and prednisolone. He was therefore administered a second IVIG (2 g/kg) and infliximab (5 mg/kg) on days 7 and 8 from the onset of fever, respectively, which resulted in an improvement of clinical symptoms. Only four Japanese cases with MIS-C were reported and all of them were responsive to IVIG. The hyperferritinemia in this case was distinctive from previously reported MIS-C cases in Japan and other cohorts and may be associated with refractoriness to IVIG therapy. Marked elevation of circulating ferritin levels is known to be induced by tumor necrosis factor-α, which plays a key role in the pathogenesis of both KD and MIS-C. Thus, for MIS-C patients with hyperferritinemia, early intervention with adjunctive infliximab may induce a more rapid resolution of inflammation and improve outcome. Because MIS-C may be heterogeneous with respect to immunopathology, genetic background, clinical phenotypes and response to therapies, optimized treatment strategies according to immunopathogenesis are required.

A young child with pediatric multisystem inflammatory syndrome successfully treated with high-dose immunoglobulin therapy

Pediatric multisystem inflammatory syndrome (MIS-C) is a disease that presents mainly in older children after coronavirus disease 2019 (COVID-19) and is associated with Kawasaki-like symptoms and multiple-organ failure. The number of cases of MIS-C has increased since April 2020, with reports mainly from Europe and the United States. The reason is unclear, but few cases of MIS-C have been reported in Asian countries, including Japan. No treatment has been established for MIS-C. In this study, we report the case of a young boy treated with IVIg for MIS-C by measuring the cytokine profile over time. A 4-year-old boy presented with Kawasaki disease-like symptoms 28 days after a positive result from polymerase chain reaction test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), meeting the World Health Organization criteria for MIS-C diagnosis. Blood tests showed lower levels of C-reactive protein and ferritin, and no decrease in lymphocyte count (<1000/μL) or more increase in fibrinogen than those reported in Japan for MIS-C in school-aged children and older. Neopterin, interleukin (IL)-6, IL-18, soluble tumor necrosis factor receptor (sTNF-R)I and sTNF-RII were all high at disease onset, but neopterin, IL-6, and sTNF-RII rapidly decreased with fever resolution after the second dose of IVIg, while IL-18 and sTNF-RI decreased bimodally. As far as we can determine, this case represents the youngest identified in Japan. The key point of difference between MIS-C and Kawasaki disease is older age in MIS-C, but attention is also needed in infants.

Characteristics of Kawasaki Disease Patients during the COVID-19 Pandemic in Japan: A Single-Center, Observational Study

Background: Under the Coronavirus disease 2019 (COVID-19) pandemic, manifestations in children with Kawasaki disease (KD) are different between the Western and the Eastern countries. Particularly, there has not been a report comparing a series of KD in Japan, where KD was originally discovered and has a large number of registered cases. Methods: We compared patients with KD under the period of the COVID-19 pandemic in Japan with the report from Italy during its reported period by a retrospective, cohort, observational study in a Japanese single center. Results: Thirty-two patients with typical KD were treated during the study period, while the Italian study reported 10 patients with the signs of KD. Concerning the proof of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection, none (0%) of our KD cases showed a positive result and one and no patients developed the macrophage activation syndrome (MAS) and Kawasaki disease shock syndrome (KDSS), respectively; however, eight (80%) patients in the Italian series were confirmed with SARS-CoV-2 infection. MAS and KDSS developed in six and five patients, respectively. Conclusions: Cases reported as COVID-19 pandemic-related KD in Italy showed significantly different clinical characteristics from the typical KD symptoms known in Japan. Although they show KD-like manifestations, we cannot conclude that SARS-CoV-2 has the same etiology of our ‘classic’ KD at the present stage.