Multisystem Inflammatory Syndrome in New Zealand Children.

New Zealand (NZ) initially adopted an elimination approach to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pre-Omicron variant, the NZ pediatric population was immunologically naïve to SARS-CoV-2. This study, utilizing national data sources, describes the NZ incidence of multisystem inflammatory syndrome in children (MIS-C) following infection with the Omicron variant. MIS-C incidence was 1.03 of 100,000 age-specific population and 0.04 of 1000 recorded SARS-CoV-2 infections.

Incidence and Clinical Phenotype of Multisystem Inflammatory Syndrome in Children After Two SARS-CoV-2 Pandemic Waves: A Croatian Prospective Nationwide Study.

This prospective nationwide study in Croatia (March 1, 2020-December 31, 2021) embraced 121 children with multisystem inflammatory syndrome. Incidence rates, disease course and outcomes were similar to those reported from other European countries. The severe acute respiratory syndrome coronavirus 2 virus Alpha strain appeared associated with a higher propensity to result in multisystem inflammatory syndrome in children than the Delta strain but did not appear related to disease severity.

Risk Factors for Multisystem Inflammatory Syndrome in Children: A Case-control Investigation.

BACKGROUND: In a 2020 pilot case-control study using medical records, we reported that non-Hispanic Black children were more likely to develop multisystem inflammatory syndrome in children (MIS-C) after adjustment for sociodemographic factors and underlying medical conditions. Using structured interviews, we investigated patient, household, and community factors underlying MIS-C likelihood. METHODS: MIS-C case patients hospitalized in 2021 across 14 US pediatric hospitals were matched by age and site to outpatient controls testing positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within 3 months of the admission date. Caregiver interviews queried race/ethnicity, medical history, and household and potential community exposures 1 month before MIS-C hospitalization (case-patients) or after SARS-CoV-2 infection (controls). We calculated adjusted odds ratios (aOR) using mixed-effects multivariable logistic regression. RESULTS: Among 275 case patients and 496 controls, race/ethnicity, social vulnerability and patient or family history of autoimmune/rheumatologic disease were not associated with MIS-C. In previously healthy children, MIS-C was associated with a history of hospitalization for an infection [aOR: 4.8; 95% confidence interval (CI): 2.1-11.0]. Household crowding (aOR: 1.7; 95% CI: 1.2-2.6), large event attendance (aOR: 1.7; 95% CI: 1.3-2.1), school attendance with limited masking (aOR: 2.6; 95% CI: 1.1-6.6), public transit use (aOR: 1.8; 95% CI: 1.4-2.4) and co-resident testing positive for SARS-CoV-2 (aOR: 2.2; 95% CI: 1.3-3.7) were associated with increased MIS-C likelihood, with risk increasing with the number of these factors. CONCLUSIONS: From caregiver interviews, we clarify household and community exposures associated with MIS-C; however, we did not confirm prior associations between sociodemographic factors and 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.

Ten-month follow-up of patients with covid-19 temporally related multi-system inflammatory syndrome in children: the experience of the children hospital of Palermo.

BACKGROUND: In Sicily, the first wave of COVID-19 showed a low epidemic impact in paediatric population, while the second and the third waves had a higher impact on clinical presentation of COVID-19 in children and a significantly higher severe outcome in patients with multisystem inflammatory syndrome in children (MIS-C), with a frequent life-threatening progression. METHODS: We describe a cohort of 22 Sicilian children (11 M; 11 F; age: 1.4-14 years), presenting with clinical features compatible with MIS-C. Patients with negative swab had a history of recent personal or parental infection. RESULTS: The following diagnostic criteria were detected: fever (100%); cheilitis and/or pharyngeal hyperaemia (86%); latero-cervical lymphadenitis (82%); rash (73%); abdominal pain and/or vomiting and/or diarrhoea (64%); conjunctivitis (64%); hands and feet oedema (18%). 59% showed cardiac involvement (6 pericardial effusion; 8 mitral valve insufficiency; 4 insufficiency of two valves; 3 coronary artery lesions (CAL)). In all the patients, treatment was started within 72 h after the admission, with intravenous immunoglobulins (IVIG) (2 g/Kg/dose), methylprednisolone (2 mg/Kg/day in 73% of patients; 30 mg/Kg/day for 3 days, followed by 2 mg/Kg/day in 27% of patients). Two patients were treated with enoxaparin. Two patients with shock, were additionally treated with vasoactive drugs, albumin, diuretics. Cardiac involvement evolved into the complete resolution of lesions in most of the patients. All the patients were included in a follow-up, to investigate on clinical outcome and resolution of organ involvement. Cardiac valve insufficiency persisted only in 18% of children, CAL persisted only in 33% of children with coronary involvement, however without the evolution into aneurisms. CONCLUSIONS: The preferred treatment strategy was more aggressive at the diagnosis of MIS-C, to block the cytokine cascade. Most of our patients, in fact, received a first-line treatment with IVIG and steroids. This approach could explain the favourable prognosis, the rapid restoring of cardiac function also in patients with MAS or shock, and the good outcome during the 10 months follow-up in all the patients.

Multisystemic Inflammatory Syndrome in Neonates: A Systematic Review.

INTRODUCTION: Multisystem inflammatory syndrome in neonates (MIS-N) related to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has increasingly been reported worldwide amid the spread of the SARS-CoV-2 pandemic. METHODS: We searched PubMed, EMBASE, and CINAHL and preprint servers (BioRxiv.org and MedRxiv.org) using a specified strategy integrating Medical Subject Headings terms and keywords until October 20, 2021. Our aim was to systematically review demographic profiles, clinical features, laboratory parameters, complications, treatments, and outcomes of neonates with MIS-N. Studies were selected when fulfilling the inclusion criteria. Articles were included if they fulfilled the World Health Organization (WHO), Centers for Disease Control (CDC) definitions of MIS-C, or our proposed definition. RESULTS: Sixteen reports of MIS-N including 47 neonates meeting MIS-N criteria were identified. Presentation included cardiovascular compromise (77%), respiratory involvement (55%), and fever in (36%). Eighty-three percent of patients received steroids, and 76% received immunoglobulin. Respiratory support was provided to 60% of patients and inotropes to 45% of patients. Five (11%) neonates died. CONCLUSION: The common presentation of MIS-N included cardiorespiratory compromise with the possibility of high mortality. Neonates with MIS-N related to SARS-CoV-2 may be at higher risk of adverse outcomes.

Incidence of multisystem inflammatory syndrome in children and the comorbidity scores in pediatric coronavirus disease 2019 cases.

BACKGROUND: We aimed to determine the incidence of multisystem inflammatory syndrome in children (MIS-C) in pediatric coronavirus disease 2019 (COVID-19) cases and to define the relationships between the need for hospitalization, the development of MIS-C, and the Charlson Comorbidity Index (CCI) and Pediatric Comorbidity Index (PCI) scores. METHODS: All pediatric COVID-19 cases between March 25, 2020, and December 28, 2020, in the Marmara University Pendik Training and Research Hospital were enrolled. Patients who needed hospitalization were determined. Hospital records were re-examined to identify those diagnosed as having MIS-C. The CCI and PCI were used to validate the comorbidity status. RESULTS: Among 2,055 pediatric COVID-19 cases, 1,340 were included in the study, and 213 patients (15.9%) had at least one comorbidity. All the patients or their parents were interviewed about the need for hospitalization, except for the acute period. Six patients had MIS-C, which corresponds to a MIS-C incidence of 0.4%. The need for hospitalization increased in the patients with comorbidities (P < 0.05). No correlation was found between the comorbidity scores and the development of MIS-C. The need for hospitalization increased in the patients with CCI scores of ≥2 and PCI scores of ≥4 (P < 0.05). CONCLUSIONS: Our study is the first to examine the incidence of MIS-C, which was 0.4%, by long-term follow up of pediatric COVID-19 cases and to demonstrate that the CCI and PCI can be used to predict the need for hospitalization and prognosis of pediatric patients with COVID-19.

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.

Multisystem Inflammatory Syndrome in Children in Western Countries? Decreasing Incidence as the Pandemic Progresses?: An Observational Multicenter International Cross-sectional Study.

BACKGROUND: SARS-CoV-2 variations as well as immune protection after previous infections and/or vaccination may have altered the incidence of multisystemic inflammatory syndrome in children (MIS-C). We aimed to report an international time-series analysis of the incidence of MIS-C to determine if there was a shift in the regions or countries included into the study. METHODS: This is a multicenter, international, cross-sectional study. We collected the MIS-C incidence from the participant regions and countries for the period July 2020 to November 2021. We assessed the ratio between MIS-C cases and COVID-19 pediatric cases in children <18 years diagnosed 4 weeks earlier (average time for the temporal association observed in this disease) for the study period. We performed a binomial regression analysis for 8 participating sites [Bogotá (Colombia), Chile, Costa Rica, Lazio (Italy), Mexico DF, Panama, The Netherlands and Catalonia (Spain)]. RESULTS: We included 904 cases of MIS-C, among a reference population of 17,906,432 children. We estimated a global significant decrease trend ratio in MIS-C cases/COVID-19 diagnosed cases in the previous month ( P < 0.001). When analyzing separately each of the sites, Chile and The Netherlands maintained a significant decrease trend ( P < 0.001), but this ratio was not statistically significant for the rest of sites. CONCLUSIONS: To our knowledge, this is the first international study describing a global reduction in the trend of the MIS-C incidence during the pandemic. COVID-19 vaccination and other factors possibly linked to the virus itself and/or community transmission may have played a role in preventing new MIS-C cases.

SARS-CoV-2 Sequelae and Postdischarge Health Care Visits Over 5 Months Follow-up Among Children Hospitalized for COVID-19 or MIS-C.

Although post-acute sequelae of COVID-19 among adult survivors has gained significant attention, data in children hospitalized for severe acute respiratory syndrome coronavirus 2 is limited. This study of commercially insured US children shows that those hospitalized with COVID-19 or multisystem inflammatory syndrome in children have a substantial burden of severe acute respiratory syndrome coronavirus 2 sequelae and associated health care visits postdischarge.

Similarities and differences between MIS-C and KD: a systematic review and meta-analysis.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a new syndrome with some clinical manifestations similar to Kawasaki disease (KD), which is difficult to distinguish. OBJECTIVE: The study aimed to characterize the demographic characteristics, clinical characteristics, laboratory features, cardiac complications, and treatment of MIS-C compared with KD. STUDY DESIGN: Studies were selected by searching the PubMed, EMBASE and so on before February 28, 2022. Statistical analyses were performed using Review Manager 5.4 software and STATA 14.0. RESULTS: Fourteen studies with 2928 participants were included. MIS-C patients tended to be older and there was no significant difference in the sex ratio. In terms of clinical characteristics, MIS-C patients were more frequently represented with respiratory, gastrointestinal symptoms and shock. At the same time, they had a lower incidence of conjunctivitis than KD patients. MIS-C patients had lower lymphocyte counts, platelet (PLT) counts, erythrocyte sedimentation rates (ESRs), alanine transaminase (ALT), and albumin levels and had higher levels of aspartate transaminase (AST), N-terminal pro-B-type natriuretic peptide (NT-pro-BNP), troponin, C-reactive protein (CRP), D-dimer, fibrinogen, ferritin, and creatinine. MIS-C patients had a higher incidence of left ventricle (LV) dysfunction, valvular regurgitation, pericardial effusion, myocarditis, and pericarditis. The incidence of coronary artery lesion (CAL) was lower in MIS-C patients [OR (95% CI): 0.52 (0.29, 0.93), p =0.03], while it was similar in the acute period. MIS-C patients had higher utilization of glucocorticoids (GCs) and lower utilization of intravenous immune globulin (IVIG). CONCLUSIONS: There were specific differences between MIS-C and KD, which might assist clinicians with the accurate recognition of MIS-C and further mechanistic research.

Multisystem inflammatory syndrome in adults: Comparison with other inflammatory conditions during the Covid-19 pandemic.

BACKGROUND: Multisystem inflammatory syndrome in adults (MIS-A) is an increasingly recognized complication of Covid-19. We assessed risk factors, clinical characteristics, and outcomes of patients with MIS-A compared with other inflammatory conditions. METHODS: We analyzed a cohort of patients ≥21 years hospitalized with MIS-A in Quebec, Canada between February 2020 and March 2021. We included comparison groups that share symptomatology or pathophysiology with MIS-A, including Kawasaki disease, toxic shock syndrome, and other Covid-19 complications. We examined characteristics of men and women at admission, and identified preexisting factors associated with MIS-A through odds ratios (OR) and 95% confidence intervals (CI) from adjusted logistic regression models. RESULTS: Among 22,251 patients in this study, 52 had MIS-A, 90 Kawasaki disease, 500 toxic shock syndrome, and 21,609 other Covid-19 complications. MIS-A was associated with an elevated risk of respiratory failure compared with Kawasaki disease (OR 7.22, 95% CI 1.26-41.24), toxic shock syndrome (OR 4.41, 95% CI 1.73-11.23), and other Covid-19 complications (OR 3.03, 95% CI 1.67-5.50). Patients with MIS-A had a greater risk of cardiac involvement, renal failure, and mortality. The data pointed towards sex-specific differences in presentation, with more respiratory involvement in women and cardiac involvement in men compared with patients that had other Covid-19 complications. Except for allergic disorders and cancer, prior medical risk factors were not associated with a greater likelihood of MIS-A. CONCLUSIONS: Patients with MIS-A have an elevated risk of mortality compared with other inflammatory conditions, with women having a predominance of respiratory complications and men cardiovascular complications.

Incidence and clinical phenotype of multisystem inflammatory syndrome in children after infection with the SARS-CoV-2 delta variant by vaccination status: a Danish nationwide prospective cohort study.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) occurs after infection with SARS-CoV-2 and its incidence is likely to depend on multiple factors, including the variant of the preceding SARS-CoV-2 infection and vaccine effectiveness. We aimed to estimate the incidence of MIS-C, and describe the clinical phenotype, following the delta variant of SARS-CoV-2 (B.1.617.2 and sublineages) according to vaccination status. We aimed to compare the incidence and clinical phenotype of MIS-C from our cohort during the pre-delta era. METHODS: This prospective, population-based cohort study included patients aged 0-17 years hospitalised with MIS-C in Denmark, according to the US Centers for Disease Control and Prevention case definition, from Aug 1, 2021, to Feb 1, 2022, a period dominated by the delta variant. We identified MIS-C cases via a nationwide research collaboration involving real-time data collection from all 18 paediatric departments. Aggregated number of SARS-CoV-2 infections by vaccination status was obtained from the Danish COVID-19 surveillance registries. The incidence of MIS-C was calculated using the estimated number of infected individuals by vaccination status. We calculated the incidence of MIS-C per 1 000 000 vaccinated and unvaccinated person-years, and estimated vaccine effectiveness as 1-incidence rate ratio using Poisson regression. Incidence and phenotype of MIS-C were compared with MIS-C cases from the first year of the pandemic. This study is registered at ClinicalTrials.gov, NCT05186597. FINDINGS: We identified 51 MIS-C cases among unvaccinated individuals and one in a fully vaccinated adolescent. The incidence of MIS-C was one in 3400 unvaccinated individuals (95% CI 2600-4600) with the delta variant and one in 9900 vaccinated individuals (95% CI 1800-390 000) with breakthrough infection. The estimated vaccine effectiveness against MIS-C after the delta variant was 94% (95% CI 55-99; p=0·0061) in individuals aged 5-17 years. The clinical phenotype during the delta wave was comparable to the pre-delta era. INTERPRETATION: We found the incidence and phenotype of MIS-C in unvaccinated children during the delta wave to be similar to the incidence during the first year of the pandemic. We found vaccine effectiveness to be high against MIS-C, which we suggest was due to protection from infection and, possibly, a decreased incidence of MIS-C after breakthrough infection. Knowledge of the incidence of MIS-C after different SARS-CoV-2 variants and the effect of vaccination might contribute to the elucidation of the extent to which MIS-C is a vaccine-preventable disease. FUNDING: National Ministry of Higher Education and Science and Innovation Fund Denmark.

Multisystem Inflammatory Syndrome Associated With COVID-19 in Children (MIS-C): A Systematic Review of Studies From India.

BACKGROUND: With wide clinical spectrum, multisystem inflammatory syndrome associated with coronavirus disease 2019 (COVID-19) in children (MIS-C) is a relatively novel condition occurring weeks to months' post SARS-CoV-2 infection. The aim was to systematically review data on clinical features, laboratory parameters and therapeutics of MIS-C from India. Methods: This systematic review was done as per the PRISMA guidelines, and quality assessment was done using NIH tool for case-series. A systematic search through databases yielded studies whose data was pooled to calculate the mean frequencies with standard deviation using GraphPad software. RESULTS: Screening of 2548 articles published till December, 2021, yielded 11 case-series. World Health Organization case definition was used widely. There was a slight preponderance of males (57%), median (IQR) age was 7 (6,7) years, 63% (n=305) required intensive care unit admissions, and mortality rate was 10% (n=261). Clinical features included fever, mucocutaneous features (72%), and gastrointestinal problems (62%) in majority. Widely used treatment was corticosteroids (76%) and intravenous immunoglobulin (62%) with other options depending on patient's state. An increased level of inflammatory markers and derangement in other parameters corroborated with disease status. Kawasaki disease like features, not reported in many studies, ranged from 4-76% of patients. CONCLUSION: MIS-C presents with a wide spectrum clinical features, increased inflammatory markers and managed as per the disease course and presentation. Future studies monitoring the long-term effects of MIS-C are recommended.

COVID-19 and multisystem inflammatory syndrome in children and adolescents.

As severe acute respiratory syndrome coronavirus 2 continues to spread worldwide, there have been increasing reports from Europe, North America, Asia, and Latin America describing children and adolescents with COVID-19-associated multisystem inflammatory conditions. However, the association between multisystem inflammatory syndrome in children and COVID-19 is still unknown. We review the epidemiology, causes, clinical features, and current treatment protocols for multisystem inflammatory syndrome in children and adolescents associated with COVID-19. We also discuss the possible underlying pathophysiological mechanisms for COVID-19-induced inflammatory processes, which can lead to organ damage in paediatric patients who are severely ill. These insights provide evidence for the need to develop a clear case definition and treatment protocol for this new condition and also shed light on future therapeutic interventions and the potential for vaccine development. TRANSLATIONS: For the French, Chinese, Arabic, Spanish and Russian translations of the abstract see Supplementary Materials section.

Multisystem inflammatory syndrome in children.

ABSTRACT: Multisystem inflammatory syndrome in children (MIS-C) is a potentially life-threatening syndrome that emerged soon after the start of the COVID-19 pandemic. This case report focuses on the general overview, case definition, epidemiology, pathogenesis, clinical findings, and management of MIS-C.

Multisystem Inflammatory Syndrome in Children During Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Delta and Omicron Variant Circulation-United States, July 2021-January 2022.

We describe 2116 multisystem inflammatory syndrome in children (MIS-C) cases reported to the Centers for Disease Control and Prevention during Delta and Omicron circulation from July 2021 through January 2022. Half of MIS-C patients were aged 5-11 years, 52% received intensive care unit-level care, and 1.1% died. Only 3.0% of eligible patients were fully vaccinated prior to MIS-C onset.