SARS-CoV-2 Polymorphisms and Multisystem Inflammatory Syndrome in Children

Multisystem inflammatory syndrome in children: A review

AIM

To comprehensively review the literature on multisystem inflammatory syndrome in children (MIS-C).

METHODS

Narrative review of relevant studies published between April 2020 and January 2024.

RESULTS

MIS-C is a SARS-CoV-2-related hyperinflammatory syndrome developing 2-6 weeks after COVID-19 in genetically susceptible individuals. Persisting fever, mucocutaneous manifestations, GI and cardiac involvement, together with lymphopenia and elevated inflammatory and cardiac markers are the main clinical features. It is believed to recognise some pathogenetic and clinical overlap with Kawasaki disease. New case definitions have been proposed after an assessment of the diagnostic performance of existing criteria; epidemiological criterion is however progressively losing its usefulness as the pandemic turns into an endemic and in the areas with the highest rates of COVID-19 vaccination. Current guidelines recommend both intravenous immunoglobulin and glucocorticoids in the first-line immunomodulatory treatment, mainly based on comparative retrospective cohorts; the actual role of biologics remains to be adequately established. Strict follow-up is mandatory, especially for those with severe cardiac involvement, as longitudinal studies evaluate the long-term evolution of cardiac damage.

CONCLUSION

In this paper, we review the epidemiological, pathogenetic, clinical and prognostic features of MIS-C, and outline the main questions which still remain unanswered after more than 3 years of research.

Unmasking the enigma: An in-depth analysis of COVID-19 impact on the pediatric population

OBJECTIVES

COVID-19, caused by the novel coronavirus, has had a profound and wide-reaching impact on individuals of all age groups across the globe, including children. This review article aims to provide a comprehensive analysis of COVID-19 in children, covering essential topics such as epidemiology, transmission, pathogenesis, clinical features, risk factors, diagnosis, treatment, vaccination, and others. By delving into the current understanding of the disease and addressing the challenges that lie ahead, this article seeks to shed light on the unique considerations surrounding COVID-19 in children and contribute to a deeper comprehension of this global health crisis affecting our youngest population.

METHODS

A comprehensive literature search was conducted to gather the most recent and relevant information regarding COVID-19 in children. Multiple renowned databases, including MEDLINE, PubMed, Scopus, as well as authoritative sources such as the World Health Organization (WHO), the U.S. Food and Drug Administration (FDA), the European Medicines Agency (EMA), and the National Institutes of Health (NIH) websites and others were thoroughly searched. The search included articles, guidelines, reports, clinical trials results and expert opinions published within the past three years, ensuring the inclusion of the latest research findings on COVID-19 in children. Several relevant keywords, including "COVID-19," "SARS-CoV-2," "children," "pediatrics," and related terms were used to maximize the scope of the search and retrieve a comprehensive set of articles.

RESULTS AND CONCLUSION

Three years since the onset of the COVID-19 pandemic, our understanding of its impact on children has evolved, but many questions remain unanswered. While SAR-CoV-2 generally leads to mild illness in children, the occurrence of severe cases and the potential for long-term effects cannot be overlooked. Efforts to comprehensively study COVID-19 in children must continue to improve preventive strategies, identify high-risk populations, and ensure optimal management. By unraveling the enigma surrounding COVID-19 in children, we can strive towards safeguarding their health and well-being in the face of future global health challenges.

Mechanisms of Immune Dysregulation in COVID-19 Are Different From SARS and MERS: A Perspective in Context of Kawasaki Disease and MIS-C

Coronaviruses have led to three major outbreaks to date-Severe Acute Respiratory Syndrome (SARS; 2002), Middle East Respiratory Syndrome (MERS; 2012) and the ongoing pandemic, Coronavirus Disease (COVID-19; 2019). Coronavirus infections are usually mild in children. However, a few children with MERS had presented with a severe phenotype in the acute phase resulting in progressive pneumonic changes with increasing oxygen dependency and acute respiratory distress requiring ventilatory support. A subset of children with a history of SARS-CoV-2 infection develops a multisystem hyper-inflammatory phenotype known as Multisystem Inflammatory Syndrome in Children (MIS-C). This syndrome occurs 4-6 weeks after infection with SARS-CoV-2 and has been reported more often from areas with high community transmission. Children with MIS-C present with high fever and often have involvement of cardiovascular, gastrointestinal and hematologic systems leading to multiorgan failure. This is accompanied by elevation of pro-inflammatory cytokines such as IL-6 and IL-10. MIS-C has several similarities with Kawasaki disease (KD) considering children with both conditions present with fever, rash, conjunctival injection, mucosal symptoms and swelling of hands and feet. For reasons that are still not clear, both KD and MIS-C were not reported during the SARS-CoV and MERS-CoV outbreaks. As SARS-CoV-2 differs from SARS-CoV by 19.5% and MERS by 50% in terms of sequence identity, differences in genomic and proteomic profiles may explain the varied disease immunopathology and host responses. Left untreated, MIS-C may lead to severe abdominal pain, ventricular dysfunction and shock. Immunological investigations reveal reduced numbers of follicular B cells, increased numbers of terminally differentiated CD4+T lymphocytes, and decreased IL-17A. There is still ambiguity about the clinical and immunologic risk factors that predispose some children to development of MIS-C while sparing others. Host-pathogen interactions in SARS, MERS and COVID-19 are likely to play a crucial role in the clinical phenotypes that manifest. This narrative review focuses on the immunological basis for development of MIS-C syndrome in the ongoing SARS-CoV-2 pandemic. To the best of our knowledge, these aspects have not been reviewed before.

Comorbidities in Children with COVID-19 and MIS-C/PIMS-TS and Risk Factors for Hospitalization, Severe Disease, Intensive Care and Death

This narrative review sums up data from the SARS-CoV-2-pandemia on preexisting disease/underlying conditions/comorbidities and risk factors in children for severe COVID-19 and MIS-C/PIMS-TS as well as hospitalization and mortality. Young infants and adolescents are at highest risk of hospital and PICU admission. Two or more comorbidities rather than single entities pose a risk for more severe courses of SARS-CoV-2 infection in children. Asthma and malignancy do not increase complication rates. MIS-C/PIMS-TS is not associated with any specific underlying disease.

Which children and young people are at higher risk of severe disease and death after hospitalisation with SARS-CoV-2 infection in children and young people: A systematic review and individual patient meta-analysis

BACKGROUND

We aimed to describe pre-existing factors associated with severe disease, primarily admission to critical care, and death secondary to SARS-CoV-2 infection in hospitalised children and young people (CYP), within a systematic review and individual patient meta-analysis.

METHODS

We searched Pubmed, European PMC, Medline and Embase for case series and cohort studies published between 1st January 2020 and 21st May 2021 which included all CYP admitted to hospital with ≥ 30 CYP with SARS-CoV-2 or ≥ 5 CYP with PIMS-TS or MIS-C. Eligible studies contained (1) details of age, sex, ethnicity or co-morbidities, and (2) an outcome which included admission to critical care, mechanical invasive ventilation, cardiovascular support, or death. Studies reporting outcomes in more restricted groupings of co-morbidities were eligible for narrative review. We used random effects meta-analyses for aggregate study-level data and multilevel mixed effect models for IPD data to examine risk factors (age, sex, comorbidities) associated with admission to critical care and death. Data shown are odds ratios and 95% confidence intervals (CI).PROSPERO: CRD42021235338.

FINDINGS

83 studies were included, 57 (21,549 patients) in the meta-analysis (of which 22 provided IPD) and 26 in the narrative synthesis. Most studies had an element of bias in their design or reporting. Sex was not associated with critical care or death. Compared with CYP aged 1-4 years (reference group), infants (aged <1 year) had increased odds of admission to critical care (OR 1.63 (95% CI 1.40-1.90)) and death (OR 2.08 (1.57-2.86)). Odds of death were increased amongst CYP over 10 years (10-14 years OR 2.15 (1.54-2.98); >14 years OR 2.15 (1.61-2.88)).The number of comorbid conditions was associated with increased odds of admission to critical care and death for COVID-19 in a step-wise fashion. Compared with CYP without comorbidity, odds ratios for critical care admission were: 1.49 (1.45-1.53) for 1 comorbidity; 2.58 (2.41-2.75) for 2 comorbidities; 2.97 (2.04-4.32) for ≥3 comorbidities. Corresponding odds ratios for death were: 2.15 (1.98-2.34) for 1 comorbidity; 4.63 (4.54-4.74) for 2 comorbidities and 4.98 (3.78-6.65) for ≥3 comorbidities. Odds of admission to critical care were increased for all co-morbidities apart from asthma (0.92 (0.91-0.94)) and malignancy (0.85 (0.17-4.21)) with an increased odds of death in all co-morbidities considered apart from asthma. Neurological and cardiac comorbidities were associated with the greatest increase in odds of severe disease or death. Obesity increased the odds of severe disease and death independently of other comorbidities. IPD analysis demonstrated that, compared to children without co-morbidity, the risk difference of admission to critical care was increased in those with 1 comorbidity by 3.61% (1.87-5.36); 2 comorbidities by 9.26% (4.87-13.65); ≥3 comorbidities 10.83% (4.39-17.28), and for death: 1 comorbidity 1.50% (0.00-3.10); 2 comorbidities 4.40% (-0.10-8.80) and ≥3 co-morbidities 4.70 (0.50-8.90).

INTERPRETATION

Hospitalised CYP at greatest vulnerability of severe disease or death with SARS-CoV-2 infection are infants, teenagers, those with cardiac or neurological conditions, or 2 or more comorbid conditions, and those who are obese. These groups should be considered higher priority for vaccination and for protective shielding when appropriate. Whilst odds ratios were high, the absolute increase in risk for most comorbidities was small compared to children without underlying conditions.

FUNDING

RH is in receipt of a fellowship from Kidney Research UK (grant no. TF_010_20171124). JW is in receipt of a Medical Research Council Fellowship (Grant No. MR/R00160X/1). LF is in receipt of funding from Martin House Children's Hospice (there is no specific grant number for this). RV is in receipt of a grant from the National Institute of Health Research to support this work (grant no NIHR202322). Funders had no role in study design, data collection, analysis, decision to publish or preparation of the manuscript.

Jumping a Moving Train: SARS-CoV-2 Evolution in Real Time

The field of molecular epidemiology responded to the SARS-CoV-2 pandemic with an unrivaled amount of whole viral genome sequencing. By the time this sentence is published we will have well surpassed 1.5 million whole genomes, more than 4 times the number of all microbial whole genomes deposited in GenBank and 35 times the total number of viral genomes. This extraordinary dataset that accrued in near real time has also given us an opportunity to chart the global and local evolution of a virus as it moves through the world population. The data itself presents challenges that have never been dealt with in molecular epidemiology, and tracking a virus that is changing so rapidly means that we are often running to catch up. Here we review what is known about the evolution of the virus, and the critical impact that whole genomes have had on our ability to trace back and track forward the spread of lineages of SARS-CoV-2. We then review what whole genomes have told us about basic biological properties of the virus such as transmissibility, virulence, and immune escape with a special emphasis on pediatric disease. We couch this discussion within the framework of systematic biology and phylogenetics, disciplines that have proven their worth again and again for identifying and deciphering the spread of epidemics, though they were largely developed in areas far removed from infectious disease and medicine.

Multisystem Inflammatory Syndrome in Children

Background

Multisystem inflammatory syndrome in children (MIS-C) is a newly recognized condition affecting children with recent infection or exposure to coronavirus disease 2019 (COVID-19). MIS-C has symptoms that affect multiple organs systems, with some clinical features resembling Kawasaki disease (KD) and toxic shock syndrome (TSS).

Objective of the Review

Our goal was to review the current literature and describe the evaluation and treatment algorithms for children suspected of having MIS-C who present to the emergency department.

Discussion

MIS-C has a wide clinical spectrum and diagnosis is based on a combination of both clinical and laboratory findings. The exact mechanism of immune dysregulation of MIS-C is not well understood. Physical findings may evolve and do not necessarily appear at the same time. Gastrointestinal, cardiac, inflammatory, and coagulopathy manifestations and dysfunction are seen frequently in MIS-C.

Conclusions

The diagnosis of MIS-C is based on clinical presentation and specific laboratory findings. In the emergency setting, a high level of suspicion for MIS-C is required in patients exposed to COVID-19. Early diagnosis and prompt initiation of therapy offer the best chance for optimal outcomes.

Late-Onset COVID-19-Related Multi-System Inflammatory Syndrome in a Middle-Aged Man

A 47-year-old man presented to the emergency department with persistent fever, chest pain and neck swelling, two months following a mild coronavirus disease 2019 (COVID-19) infection. He was found to have persistent fever, hypotension, cervical lymphadenitis, myocarditis, and acute kidney injury, collectively meeting the multi-system inflammatory syndrome criteria in adults (MIS-A). The patient responded well to methylprednisolone therapy and intravenous immunoglobulins with a complete clinical recovery. This case demonstrates that MIS-A can present as a delayed complication of COVID-19 infection.

Coronavirus Disease 2019-Related Multisystem Inflammatory Syndrome in Children: A Systematic Review and Meta-Analysis

Background

This study aimed to describe the clinical symptoms, laboratory findings, treatment, and outcomes of coronavirus disease 2019-related multisystem inflammatory syndrome in children to provide a reference for clinical practice.

Methods

We employed a literature search of databases such as PubMed, Web of Science, EMBASE, and Johns Hopkins University for articles on COVID-19-related multisystem inflammatory syndrome in children published between April 1, 2020, and January 15, 2021. High-quality articles were selected for analysis on the basis of their quality standard scores. Using R3.6.3 software, meta-analyses of random- or fixed-effects models were used to determine the prevalence of comorbidities. Subgroup analysis was also performed to determine heterogeneity.

Results

A total of 57 articles (2,290 pediatric patients) were included in the study. Clinical Manifestations. :ncidences of fever, gastrointestinal symptoms, respiratory symptoms, and musculoskeletal symptoms (myalgias or arthralgias) were 99.91% (95% CI: 99.67–100%), 82.72% (95% CI: 78.19–86.81%), 53.02% (45.28–60.68%), and 14.16% (95% CI: 8.4–21.12%), respectively. The incidences of rash, conjunctival injection, lymphadenopathy, dry cracked lips, neurologic symptoms (headache, altered mental status, or confusion), swollen hands and feet, typical Kawasaki disease, and atypical Kawasaki disease were 59.34% (95% CI: 54.73–63.87%), 55.23% (95% CI: 50.22–60.19%), 27.07% (95% CI: 19.87–34.93%), 46.37% (95% CI: 39.97–52.83%), 28.87% (95% CI: 22.76–35.40%), 28.75% (95% CI: 21.46–36.64%), 17.32% (95% CI: 15.44–19.29%), and 36.19% (95% CI: 21.90–51.86%), respectively. The incidences of coronary artery dilation, aneurysm, pericardial effusion, myocarditis, myocardial dysfunction, high troponin, and N-terminal pro-B-type natriuretic peptide were 17.83%, 6.85%, 20.97%, 35.97%, 56.32%, 76.34%, and 86.65%, respectively. The incidences of reduced lymphocytes, thrombocytopenia, hypoalbuminemia, elevated C-reactive protein, ferritin, LDH, interleukin-6, PCT, and FIB were 61.51%, 26.42%, 77.92%, 98.5%, 86.79%, 80.59%, 89.30%, 85.10%, and 87.01%, respectively. PICU Hospitalization Rate and Mortality. The incidences of PICU hospitalization or with shock were 72.79% and 55.68%, respectively. The mortality rate was 1.00%. Conclusion and Relevance. PICU hospitalization and shock rates of multisystem inflammatory syndrome in children associated with COVID-19 were high, and its cumulative multiorgans and inflammatory indicators are increased, but if treated in time, the mortality rate was low.