Immunology of Multisystem Inflammatory Syndrome after COVID-19 in Children: A Review of the Current Evidence

Risk Factors Associated with Intensive Care Admission in Children with Severe Acute Respiratory Syndrome Coronavirus 2-Related Multisystem Inflammatory Syndrome (MIS-C) in Latin America: A Multicenter Observational Study of the REKAMLATINA Network

Background: Multisystem inflammatory syndrome in children (MIS-C) associated with coronavirus disease 2019 varies widely in its presentation and severity, with low mortality in high-income countries. In this study in 16 Latin American countries, we sought to characterize patients with MIS-C in the pediatric intensive care unit (PICU) compared with those hospitalized on the general wards and analyze the factors associated with severity, outcomes, and treatment received. Study Design: An observational ambispective cohort study was conducted including children 1 month to 18 years old in 84 hospitals from the REKAMLATINA network from January 2020 to June 2022. Results: A total of 1239 children with MIS-C were included. The median age was 6.5 years (IQR 2.5-10.1). Eighty-four percent (1043/1239) were previously healthy. Forty-eight percent (590/1239) were admitted to the PICU. These patients had more myocardial dysfunction (20% vs 4%; P < 0.01) with no difference in the frequency of coronary abnormalities (P = 0.77) when compared to general ward subjects. Of the children in the PICU, 83.4% (494/589) required vasoactive drugs, and 43.4% (256/589) invasive mechanical ventilation, due to respiratory failure and pneumonia (57% vs 32%; P = 0.01). On multivariate analysis, the factors associated with the need for PICU transfer were age over 6 years (aOR 1.76 95% CI 1.25-2.49), shock (aOR 7.06 95% CI 5.14-9.80), seizures (aOR 2.44 95% CI 1.14-5.36), thrombocytopenia (aOR 2.43 95% CI 1.77-3.34), elevated C-reactive protein (aOR 1.89 95% CI 1.29-2.79), and chest x-ray abnormalities (aOR 2.29 95% CI 1.67-3.13). The overall mortality was 4.8%. Conclusions: Children with MIS-C who have the highest risk of being admitted to a PICU in Latin American countries are those over age six, with shock, seizures, a more robust inflammatory response, and chest x-ray abnormalities. The mortality rate is five times greater when compared with high-income countries, despite a high proportion of patients receiving adequate treatment.

Complications of Multisystem Inflammatory Syndrome Associated with SARS-CoV-2 Infection-Many Facets of One Disease-A Literature Review Based on a Case Report

Multisystem inflammatory syndrome in children (MIS-C) is a disease that made its mark in the early days of the COVID-19 pandemic due to the diverse course and symptoms affecting multiple body systems. It is a condition that develops in pediatric patients about 2-6 weeks after contact with a person infected with the SARS-CoV-2 virus. In many instances, MIS-C has caused multiple organ failure, with particularly severe complications involving the cardiovascular system and manifesting as hypotension, various cardiac arrhythmias, myocarditis or coronary artery lesions resembling those seen in Kawasaki disease. Currently, the incidence of MIS-C is about 1-3 per 1000 children, with a decreasing trend in recent years due to the introduction of immunization against the SARS-CoV-2 virus for children as young as 6 months. In our paper, we present the case of a patient with a severe course of MIS-C with numerous cardiovascular and neurological complications, in whom the symptoms of the disease were managed by administering biological treatment. We also present a review of the literature on the subject, which shows how many different facets this disease can have and that physicians still need to remain alert, as there are cases of severe MIS-C, especially in unvaccinated patients.

Comparing the immune abnormalities in MIS-C to healthy children and those with inflammatory disease reveals distinct inflammatory cytokine production and a monofunctional T cell response

Multisystem inflammatory syndrome in children (MIS-C) is a severe, hyperinflammatory disease that occurs after exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The underlying immune pathology of MIS-C is incompletely understood, with limited data comparing MIS-C to clinically similar paediatric febrile diseases at presentation. SARS-CoV-2-specific T cell responses have not been compared in these groups to assess whether there is a T cell profile unique to MIS-C. In this study, we measured inflammatory cytokine concentration and SARS-CoV-2-specific humoral immunity and T cell responses in children with fever and suspected MIS-C at presentation (n = 83) where MIS-C was ultimately confirmed (n = 58) or another diagnosis was made (n = 25) and healthy children (n = 91). Children with confirmed MIS-C exhibited distinctly elevated serum IL-10, IL-6, and CRP at presentation. No differences were detected in SARS-CoV-2 spike IgG serum concentration, neutralisation capacity, antibody dependant cellular phagocytosis, antibody dependant cellular cytotoxicity or SARS-CoV-2-specific T cell frequency between the groups. Healthy SARS-CoV-2 seropositive children had a higher proportion of polyfunctional SARS-CoV-2-specific CD4+ T cells compared to children with MIS-C and those with other inflammatory or infectious diagnoses, who both presented a largely monofunctional SARS-CoV-2-specific CD4+ T cell profile. Treatment with steroids and/or intravenous immunoglobulins resulted in rapid reduction of inflammatory cytokines but did not affect the SARS-CoV-2-specific IgG or CD4+ T cell responses in MIS-C. In these data, MIS-C had a unique cytokine profile but not a unique SARS-CoV-2 specific humoral or T cell cytokine response.

COVID-19 and Laboratory Markers from Romanian Patients-A Narrative Review

COVID-19 has significantly impacted the whole world, and Romania was no exception. Biomarkers play a crucial role in understanding and managing the disease. However, research regarding laboratory analyses for patients with COVID-19 is fairly limited. For detection, PCR testing is still considered the golden standard, while antibodies are still useful for monitoring both patients and their vaccination status. In our country, biomarkers such as CRP, LDH, transaminases, cardiac, and iron markers have been used to assess the status of patients and even predict illness outcome. CRP, IL-6, LDH, FER, fibrinogen, creatinine, and vitamin D levels have been associated with increased severity, risk of ICU admission, and death. Cardiac markers and D-dimers are also good predictors, but their role seems more important in patients with complications. HDL cholesterol and BUN levels were also suggested as potential biomarkers. Hematological issues in SARS-CoV-2 infections include neutrophilia, lymphopenia and their ratio, while PCT, which is a marker of bacterial infections, is better to be used in patients with co- or supra-infections. The current research is a narrative review that focuses on the laboratory results of Romanian COVID-19 patients. The goal of this article is to provide an update on the research on biomarkers and other laboratory tests conducted inside the borders of Romania and identify gaps in this regard. Secondly, options for further research are discussed and encouraged.