Prolonged Thrombocytopenia in a Case of MIS-C in a Vaccinated Child.

Multisystem inflammatory syndrome in children (MIS-C) has been extensively described in patients following severe acute respiratory syndrome coronavirus 2 infection. There are now questions about what MIS-C may look like in vaccinated children. Multisystem inflammatory syndrome in children has many clinical and laboratory features in common with other inflammatory disorders including Kawasaki disease and toxic shock syndrome. Rheumatologic conditions can present with similar musculoskeletal complaints and elevated inflammatory markers. Laboratory markers and clinical symptoms of MIS-C usually improve once therapy is begun. We describe a child with persistent thrombocytopenia as an example of variable presentation of MIS-C in vaccinated children. This case report discusses an atypical progression of MIS-C in a vaccinated child with a known prior positive COVID-19 polymerase chain reaction (PCR) test. She presented with nonspecific abdominal pain and fever and was found to have elevated inflammatory markers, lymphopenia, and thrombocytopenia. Intravenous immunoglobulin and steroid treatment failed to induce rapid recovery in her clinical condition or thrombocytopenia. Rheumatologic, hematologic, oncologic, and infectious causes were considered and worked up due to the uncertainty of her case and persistence of pancytopenia but ultimately were ruled out with extensive testing and monitoring. It was key to include a broad differential including viral-induced bone marrow suppression, idiopathic thrombocytopenic purpura, secondary hemophagocytic lymphohistiocytosis, systemic juvenile idiopathic arthritis, and malignancy. The spectrum of MIS-C and response to treatment continues to evolve, and prior vaccination in this child's case complicated the clinical picture further. Additional evaluation of MIS-C in vaccinated cases will permit characterization of the range of MIS-C presentation and response to standard therapy.

Notch1 signaling impairs regulatory T cells during multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome in children (MIS-C) is a rare pediatric inflammatory disorder characterized by immune cell hyperactivation, cytokine storm, and the production of autoantibodies. The mechanisms underlying such immune dysregulation still need to be unraveled. In this issue of the JCI, Benamar et al. demonstrated the critical role of the Notch receptor 1/CD22 (Notch1/CD22) axis in Tregs, which, when activated, impairs Treg functions and promotes inflammation. They showed that the Notch1/CD22 axis contributed to dysregulated immune responses in MIS-C. These findings may have implications for MIS-C and many other inflammatory diseases.

Multisystem Inflammatory Syndrome.

The novel coronavirus (severe acute respiratory syndrome coronavirus-2), also referred to as coronavirus disease 2019, has caused a global pandemic that cost more than 900,000 deaths and affected nearly 80 million Americans since the start of the pandemic in early 2020. A majority of cases have primarily been reported in the adult population. Initially, lower morbidity and mortality rates were noted in children, compared with adults. However, some pediatric patients have been shown to develop a rare, but severe complication of severe acute respiratory syndrome coronavirus-2 infection, referred to as Multisystem Inflammatory Syndrome in Children. The condition has now been reported in adults as well. In this article, the origins, clinical features, pathogenesis, treatment, and latest literature on multisystem inflammatory syndrome are explored.

COVID-19 Vaccine Reactogenicity and Vaccine Attitudes Among Children and Parents/Guardians After Multisystem Inflammatory Syndrome in Children or COVID-19 Hospitalization: September 2021-May 2022.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a multiorgan hyperinflammatory condition following SARS-CoV-2 infection. Data on COVID-19 vaccine adverse events and vaccine attitudes in children with prior MIS-C are limited. We described characteristics associated with COVID-19 vaccination, vaccine adverse events and vaccine attitudes in children with a history of MIS-C or COVID-19 and their parents/guardians. METHODS: We enrolled children previously hospitalized for MIS-C or COVID-19 from 3 academic institutions. We abstracted charts and interviewed children and parents/guardians regarding vaccine adverse events and acceptability. RESULTS: Of 163 vaccine-eligible children enrolled with a history of MIS-C and 70 with history of COVID-19, 51 (31%) and 34 (49%), respectively, received mRNA COVID-19 vaccine a median of 10 (Interquartile Range 6-13) months after hospital discharge. Among 20 children with MIS-C and parents/guardians who provided interviews, local injection site reaction of brief duration (mean 1.8 days) was most commonly reported; no children required medical care within 2 weeks postvaccination. Vaccine survey results of interviewed, vaccinated children and their parents/guardians: of 20 children with MIS-C and 15 children with COVID-19, 17 (85%) and 13 (87%), respectively, listed doctors in the top 3 most trusted sources for vaccine information; 13 (65%) and 9 (60%) discussed vaccination with their doctor. CONCLUSIONS: COVID-19 vaccination was well tolerated in children with prior MIS-C or COVID-19 participating in our investigation. Parents/guardians regarded their children's doctors as a trusted source of information for COVID-19 vaccines, and most vaccinated children's parents/guardians had discussed COVID-19 vaccination for their child with their doctor.

Multiple MIS-C Readmissions and Giant Coronary Aneurysm After COVID-19 Illness and Vaccination: A Case Report.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) rarely involves delayed giant coronary aneurysms, multiple readmissions or occurrence after COVID-19 vaccination. METHODS: We describe a child with all 3 of these unusual features. We discuss his clinical presentation, medical management, review of the current literature and CDC guidance recommendations regarding further vaccinations. RESULTS: A 5-year-old boy had onset of MIS-C symptoms 55 days after COVID-19 illness and 15 days after receiving his first BNT162b2 COVID-19 vaccination. He was admitted 3 times for MIS-C, and twice after his steroid dose was tapered. On his initial admission, he was given intravenous immunoglobulin and steroids. During his second admission, new, moderate coronary dilation was noted, and he was treated with intravenous immunoglobulin and steroids. At his last admission, worsening coronary dilation was noted, and he was treated with infliximab and steroids. During follow-up, he had improvement in his coronary artery dilatation. However, his inflammatory markers increased after steroid wean, and his steroid taper was further extended, after which time his inflammatory markers improved. This is the only such reported case of a patient who was admitted 3 times for MIS-C complications after COVID-19 vaccination. CONCLUSION: MIS-C rarely involves delayed giant coronary aneurysms, multiple readmissions, or occurrence after COVID-19 vaccination. Whether our patient's COVID-19 vaccine 6 weeks after COVID-19 illness contributed to his MIS-C is unknown. After consultation with the CDC-funded Clinical Immunization Safety Assessment Project, the patient's care team decided against further COVID-19 vaccination until at least 3 months post normalization of inflammatory markers.

Multisystem Inflammatory Syndrome.

The novel coronavirus (severe acute respiratory syndrome coronavirus-2), also referred to as coronavirus disease 2019, has caused a global pandemic that cost more than 900,000 deaths and affected nearly 80 million Americans since the start of the pandemic in early 2020. A majority of cases have primarily been reported in the adult population. Initially, lower morbidity and mortality rates were noted in children, compared with adults. However, some pediatric patients have been shown to develop a rare, but severe complication of severe acute respiratory syndrome coronavirus-2 infection, referred to as Multisystem Inflammatory Syndrome in Children. The condition has now been reported in adults as well. In this article, the origins, clinical features, pathogenesis, treatment, and latest literature on multisystem inflammatory syndrome are explored.

Multisystem inflammatory syndrome in adults: Characteristics, treatment, and outcomes.

Following the rapidly increasing number of multisystem inflammatory syndromes in children (MIS-C), a similar clinical scenario has been observed in adult patients. Although its prevalence is low and probably related to underdiagnosis, its development can be associated with high mortality. Multisystem inflammatory syndrome in adults (MIS-A) can develop following both asymptomatic and symptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and in previously healthy people. Like MIS-C, MIS-A is a multisystem disease that can involve the cardiovascular, respiratory, gastrointestinal, dermatologic, hematologic, and neurologic systems. In addition to the clinical manifestations, the diagnosis of MIS-A requires laboratory evidence of inflammation and SARS-CoV-2 infection. The appropriate treatment for MIS-A remains unclear; anti-inflammatory agents, including intravenous immunoglobulin and corticosteroids, are commonly used. However, there are still many unknowns regarding MIS-A. Further studies are needed to determine the true prevalence, pathogenesis, and effective treatment for MIS-A.

Multisystem Inflammatory Syndrome in Children (MIS-C): Comparison of the First and the Second Waves.

This study comparing the different parameters of children suffering from multisystem inflammatory syndrome in children (MIS-C) in Kolkata, India, during the two waves (July, 2020-January, 2021 and April-July, 2021) showed that the second wave had a higher propensity of Kawasaki disease (KD)-like presentation, cardiac affection and pediatric intensive care unit admission, and increased incidence of use of steroids for treatment.

Tender cervical lymphadenitis as a herald of multi-system inflammatory syndrome in COVID-19 infection of children and adolescents: a report of two cases.

BACKGROUND: Post-COVID-19 multisystem inflammatory syndrome (MIS) has been increasingly recognized but fever with isolated tender cervical lymphadenitis as the initial presentation has been rarely reported. We present 2 female patients one a child and the other an adolescent. CASE PRESENTATION: Case 1 was a 13-year-old girl who presented with tender cervical lymphadenopathy and fever 3-weeks post-COVID-19, and then developed features of MIS 5 days later. Case 2, also female, was 18 years old. She had no history of COVID-19 infection or immunization but had a serologic diagnosis of COVID-19. She similarly presented with fever and tender cervical lymphadenopathy, and then progressed rapidly to develop features of MIS. Both patients responded well to treatment with immunosuppressants and intravenous immunoglobulin. CONCLUSION: Tender cervical lymphadenopathy could be the herald of multi-system inflammatory syndrome following COVID-19 infection among children and adolescents, which the clinicians must have a good suspicion about.

Prolonged Thrombocytopenia in a Case of MIS-C in a Vaccinated Child.

Multisystem inflammatory syndrome in children (MIS-C) has been extensively described in patients following severe acute respiratory syndrome coronavirus 2 infection. There are now questions about what MIS-C may look like in vaccinated children. Multisystem inflammatory syndrome in children has many clinical and laboratory features in common with other inflammatory disorders including Kawasaki disease and toxic shock syndrome. Rheumatologic conditions can present with similar musculoskeletal complaints and elevated inflammatory markers. Laboratory markers and clinical symptoms of MIS-C usually improve once therapy is begun. We describe a child with persistent thrombocytopenia as an example of variable presentation of MIS-C in vaccinated children. This case report discusses an atypical progression of MIS-C in a vaccinated child with a known prior positive COVID-19 polymerase chain reaction (PCR) test. She presented with nonspecific abdominal pain and fever and was found to have elevated inflammatory markers, lymphopenia, and thrombocytopenia. Intravenous immunoglobulin and steroid treatment failed to induce rapid recovery in her clinical condition or thrombocytopenia. Rheumatologic, hematologic, oncologic, and infectious causes were considered and worked up due to the uncertainty of her case and persistence of pancytopenia but ultimately were ruled out with extensive testing and monitoring. It was key to include a broad differential including viral-induced bone marrow suppression, idiopathic thrombocytopenic purpura, secondary hemophagocytic lymphohistiocytosis, systemic juvenile idiopathic arthritis, and malignancy. The spectrum of MIS-C and response to treatment continues to evolve, and prior vaccination in this child's case complicated the clinical picture further. Additional evaluation of MIS-C in vaccinated cases will permit characterization of the range of MIS-C presentation and response to standard therapy.

Inborn errors of OAS-RNase L in SARS-CoV-2-related multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome in children (MIS-C) is a rare and severe condition that follows benign COVID-19. We report autosomal recessive deficiencies of OAS1, OAS2, or RNASEL in five unrelated children with MIS-C. The cytosolic double-stranded RNA (dsRNA)-sensing OAS1 and OAS2 generate 2'-5'-linked oligoadenylates (2-5A) that activate the single-stranded RNA-degrading ribonuclease L (RNase L). Monocytic cell lines and primary myeloid cells with OAS1, OAS2, or RNase L deficiencies produce excessive amounts of inflammatory cytokines upon dsRNA or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulation. Exogenous 2-5A suppresses cytokine production in OAS1-deficient but not RNase L-deficient cells. Cytokine production in RNase L-deficient cells is impaired by MDA5 or RIG-I deficiency and abolished by mitochondrial antiviral-signaling protein (MAVS) deficiency. Recessive OAS-RNase L deficiencies in these patients unleash the production of SARS-CoV-2-triggered, MAVS-mediated inflammatory cytokines by mononuclear phagocytes, thereby underlying MIS-C.

Decreasing Incidence of the Multisystem Inflammatory Syndrome in Children Over 3 Pandemic Waves.

In this nationwide retrospective study, a substantial decline in the incidence of multisystem inflammatory syndrome in children over 3 successive pandemic waves characterized by different severe acute respiratory syndrome coronavirus 2 variants was documented-from 3.4 of 1000 to 1.1 of 1000 and finally to 0.25 of 1000 confirmed severe acute respiratory syndrome coronavirus 2 positive cases (P < 0.0001), respectively, whereas clinical findings and severity did not significantly vary.

Host genetic susceptibility underlying SARS-CoV-2-associated Multisystem Inflammatory Syndrome in Brazilian Children.

BACKGROUND: Multisystem Inflammatory Syndrome in Children (MIS-C) is a life-threatening complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which manifests as a hyper inflammatory process with multiorgan involvement in predominantly healthy children in the weeks following mild or asymptomatic coronavirus disease 2019 (COVID-19). However, host monogenic predisposing factors to MIS-C remain elusive. METHODS: Herein, we used whole exome sequencing (WES) on 16 MIS-C Brazilian patients to identify single nucleotide/InDels variants as predisposition factors associated with MIS-C. RESULTS: We identified ten very rare variants in eight genes (FREM1, MPO, POLG, C6, C9, ABCA4, ABCC6, and BSCL2) as the most promising candidates to be related to a higher risk of MIS-C development. These variants may propitiate a less effective immune response to infection or trigger the inflammatory response or yet a delayed hyperimmune response to SARS-CoV-2. Protein-Protein Interactions (PPIs) among the products of the mutated genes revealed an integrated network, enriched for immune and inflammatory response mechanisms with some of the direct partners representing gene products previously associated with MIS-C and Kawasaki disease (KD). In addition, the PPIs direct partners are also enriched for COVID-19-related gene sets. HLA alleles prediction from WES data allowed the identification of at least one risk allele in 100% of the MIS-C patients. CONCLUSIONS: This study is the first to explore host MIS-C-associated variants in a Latin American admixed population. Besides expanding the spectrum of MIS-C-associated variants, our findings highlight the relevance of using WES for characterising the genetic interindividual variability associated with COVID-19 complications and ratify the presence of overlapping/convergent mechanisms among MIS-C, KD and COVID-19, crucial for future therapeutic management.