Biologically informed machine learning modeling of immune cells to reveal physiological and pathological aging process (preprint)

The immune system undergoes progressive functional remodeling from neonatal stages to old age. Therefore, understanding how aging shapes immune cell function is vital for precise treatment of patients at different life stages. Here, we constructed the first transcriptomic atlas of immune cells encompassing human lifespan, ranging from newborns to supercentenarians, and comprehensively examined gene expression signatures involving cell signaling, metabolism, differentiation, and functions in all cell types to investigate immune aging changes. By comparing immune cell composition among different age groups, HLA highly expressing NK cells and CD83 positive B cells were identified with high percentages exclusively in the teenager (Tg) group, whereas CD4_CTL precursors were exclusively enriched in the supercentenarian (Sc) group. Notably, we found that the biological age (BA) of pediatric COVID-19 patients with multisystem inflammatory syndrome accelerated aging according to their chronological age (CA). Besides, we proved that inflammatory shift- myeloid abundance and signature correlate with the progression of complications in Kawasaki disease (KD). Finally, based on those age-related immune cell compositions, we developed a novel BA prediction model, PHARE (https://xiazlab.org/phare/), which applies to both scRNA-seq and bulk RNA-seq data. Overall, our study revealed changes in immune cell proportions and function associated with aging, both in health and disease, and provided a novel tool for successfully capturing features that accelerate or delay aging.

A genetically modulated Toll-like-receptor-tolerant phenotype in peripheral blood cells of children with multisystem inflammatory syndrome. (preprint)

Dysregulated innate immune responses contribute to multisystem inflammatory syndrome in children (MIS-C), characterized by gastrointestinal, mucocutaneous, and/or cardiovascular injury occurring weeks after SARS-CoV-2 exposure. To investigate innate immune functions in MIS-C, we stimulated ex vivo peripheral blood cells from MIS-C patients with agonists of Toll-like receptors (TLR), key innate immune response initiators. We found severely dampened cytokine responses and elevated gene expression of negative regulators of TLR signaling. Increased plasma levels of zonulin, a gut leakage marker, were also detected. These effects were also observed in children enrolled months after MIS-C recovery. Moreover, cells from MIS-C children carrying rare genetic variants of lysosomal trafficking regulator (LYST) were less refractory to TLR stimulation and exhibited lysosomal and mitochondrial abnormalities with altered energy metabolism. Our results strongly suggest that MIS-C hyperinflammation and/or excessive or prolonged stimulation with gut-originated TLR ligands drive immune cells to a lasting refractory state. TLR hyporesponsiveness is likely beneficial, as suggested by excess lymphopenia among rare LYST variant carriers. Our findings point to cellular mechanisms underlying TLR hyporesponsiveness; identify genetic determinants that may explain the MIS-C clinical spectrum; suggest potential associations between innate refractory states and long COVID; and highlight the need to monitor long-term consequences of MIS-C.

Unusual presentation of Thrombotic Thrombocytopenic Purpra in a newly diagnosed pediatric patient with Systemic Lupus Erythematosus in the setting of MIS-C (preprint)

The understanding of Coronavirus disease 2019 (COVID-19) immune dysregulation is evolving. Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease with alternations in both innate and adaptive immunity, probably caused by a complex interplay of genetics and environmental exposure with various triggers. A rare hematological complication of SLE as well as recently reported in adult with COVID-19 is thrombotic thrombocytopenic purpura (TTP). We report a pediatric case with features suggestive of multisystem inflammatory syndrome in children (MIS-C) with coronary artery ectasia, TTP, autoimmune hemolytic anemia (AIHA) and thrombocytopenia with new onset SLE as well.

COVID-19 induced Multisystem Inflammatory Syndrome in Adult and Acute Limb Ischemia. (preprint)

The patient presented with a chief complaint of lower extremity pain was found to be positive SARS-CoV-2 test. Contrast-enhanced computed tomography scans showed endocarditis, vasculitis and lower extremity ischemia. Despite we treated the patient with dexamethasone, the patient died.

Cancer does not wait: safeguarding care for pediatric acute lymphoblastic leukemia patients during the COVID-19 pandemic in a Mexican hospital. (preprint)

Introduction: Safeguarding care of acute lymphoblastic leukemia (ALL) patients during the COVID-19 pandemic has posed a significant challenge to health systems. We documented continuity (timeliness and compliance) of curative treatment in pediatric ALL patients, and the incidence and outcomes of patients infected with SARS-Cov2 in our institution. Materials and methods: We included all ALL patients aged <16 years who received treatment in “Hospital Universitario Dr. José Eleuterio Gonzalez” from March 2020 to June 2021. The causes of non-compliance and the outcomes of patients with COVID-19 were reported. Results: We analyzed 553 visits from 89 patients with ALL. Chemotherapy administration was timely and compliant with our treatment protocol in 83% (n=459) of the records reviewed. Treatment continuity goals of ≥80% were achieved for all treatment phases, except for the consolidation (66%) and intermediate maintenance phases (60%). The main causes of treatment delays or treatment modifications included lack of financial resources (2.5%), lack of inpatient beds (1.8%) and chemotherapy stock-outs (1.3%), and the treatment abandonment rate was 3.3%. Twenty-two patients (24.7%) were diagnosed with COVID-19. Of these, seven (32%) developed pneumonia, five (22.7%) required oxygen, and two (9%) developed multisystem inflammatory syndrome. For patients with COVID-19, the median length of stay was 9.5 days, and the 30-day mortality rate was 4.5%. Discussion: The continuity of curative treatment for ALL in the context of COVID-19 was >80% in our hospital. Adapting diagnosis and treatment protocols and implementing strategies to minimize the risk of infection were fundamental to safeguarding continuity care for cancer patients.

MIS-C, inherited metabolic diseases and methylmalonic acidemia: a case report and review of the literature (preprint)

Bacground Methylmalonic acidemia (MMA) secondary to mutase deficiency, mut0, is an inborn error of metabolism causing complete enzyme deficiency. Multisystem Inflammatory Syndrome in Children (MIS-C) is a hyperinflammatory syndrome characterized by fever, inflammation, multiorgan impairment that manifests 14–60 days after the SARS-CoV-2 infection in patients aged < 21 years. Case presentation We describe the clinical case of a 2-year-old child with MMA secondary to mutase deficiency, with the documented homozygous mutation c.2179 C > T of MMUT gene, associated to mut0 phenotype. One month after SARS-CoV-2 infection, he presented fever, rash, significant increase of C-reactive protein (CRP), ferritin, triglycerides, (interleukin) IL-6, PRO-BNP, compatible with the diagnosis of MIS-C. He was treated with intravenous immunoglobulins (2gr/Kg), methylprednisolone (2 mg/Kg/day), with rapid clinical improvement. Ten days later, he showed the worsening of clinical conditions, with the recurrence of fever, vasculitic rash with palmoplantar extension, further increase of ferritin (1033 ug/l), IL-6 (146 pg/ml), PRO-BNP (5117 pg/ml), triglycerides, anemia, thrombocytopenia, metabolic acidosis with hyperlactatemia (180 mg/dl), increased urinary methylmalonic acid (200 mmol/mCreat), multiorgan failure. He was treated with sodium bicarbonate, thiamine, coenzyme Q, vitamin C, methylprednisolone and anakinra (2 mg/Kg/day). Three days after the start of anakinra, he showed a significant improvement of clinical and biochemical parameters and defervescence. 20 days later, a sepsis from Staphylococcus Aureus and Candida Albicans required the interruption of anakinra, with the worsening of the clinical and haematological parameters and the exitus. Conclusions Only a few cases of patients with inherited metabolic diseases (IMD) and MIS-C are described. However, to our knowledge, this is the first case of MIS-C in MMA described. The description of these clinical cases is a precious lesson for pediatricians to manage IMD therapeutic emergencies. Anakinra must be considered as a safe treatment of choice in IMD patients with MIS-C. The use of anakinra in patients with a severe form of MMA is safe and can be employed to treat MIS-C, gaining a substantial clinical and biochemical improvement.

Development and validation of a federated learning framework for detection of subphenotypes of multisystem inflammatory syndrome in children (preprint)

Background: Multisystem inflammatory syndrome in children (MIS-C) is a severe post-acute sequela of SARS-CoV-2 infection. The highly diverse clinical features of MIS-C necessities characterizing its features by subphenotypes for improved recognition and treatment. However, jointly identifying subphenotypes in multi-site settings can be challenging. We propose a distributed multi-site latent class analysis (dMLCA) approach to jointly learn MIS-C subphenotypes using data across multiple institutions. Methods We used data from the electronic health records (EHR) systems across nine U.S. childrens hospitals. Among the 3,549,894 patients, we extracted 864 patients < 21 years of age who had received a diagnosis of MIS-C during an inpatient stay or up to one day before admission. Using MIS-C conditions, laboratory results, and procedure information as input features for the patients, we applied our dMLCA algorithm and identified three MIS-C subphenotypes. As validation, we characterized and compared more granular features across subphenotypes. To evaluate the specificity of the identified subphenotypes, we further compared them with the general subphenotypes identified in the COVID-19 infected patients. Findings Subphenotype 1 (46.1%) represents patients with a mild manifestation of MIS-C not requiring intensive care, with minimal cardiac involvement. Subphenotype 2 (25.3%) is associated with a high risk of shock, cardiac and renal involvement, and an intermediate risk of respiratory symptoms. Subphenotype 3 (28.6%) represents patients requiring intensive care, with a high risk of shock and cardiac involvement, accompanied by a high risk of >4 organ system being impacted. Importantly, for hospital-specific clinical decision-making, our algorithm also revealed a substantial heterogeneity in relative proportions of these three subtypes across hospitals. Properly accounting for such heterogeneity can lead to accurate characterization of the subphenotypes at the patient-level. Interpretation Our identified three MIS-C subphenotypes have profound implications for personalized treatment strategies, potentially influencing clinical outcomes. Further, the proposed algorithm facilitates federated subphenotyping while accounting for the heterogeneity across hospitals.

Current Literature Review of COVID Eye Infections in the Pediatric Population and the Beneficial Effect of Isolated Treatment of COVID Uveitis (Panuveitis) in a Child after Isolated Administration of Depomedrol under the Tenon Capsule — a Case Report (preprint)

Coronavirus disease 2019 (COVID-19), can manifest with ocular symptoms. These symptoms can be divided into isolated events attributed to COVID-19 and those occurring in multisystem inflammatory syndrome in children (MIS-C), a newly diagnosed disease entity associated with COVID-19 infection. Currently, the literature lacks specific guidelines and treatment regimens for COVID-19 ocular symptoms, especially in children.

Comparison of the type and prevalence of cardiac involvement among children hospitalized with COVID-19 and Multisystem Inflammatory Syndrome in Children: A cross-sectional study (preprint)

Background: Since the outbreak of COVID-19 in late 2019, more than 772 million individuals have been infected. There are numerous reports and studies about the complications and effects of this viral disease on different systems of the body. One of the important complications of COVID-19 in children is a condition named “Multisystem Inflammatory syndrome in Children (MIS-C)” which has some manifestations similar to Kawasaki disease or sepsis. Methods: In this study, we retrospectively compared the cardiac complications of COVID-19 and MIS-C in individuals under 18 years old of age, admitted to the Children’s Hospital of Bandar-Abbas, Iran, in an 18-months period of time. Results: The prevalence of mitral regurgitation in MIS-C and COVID-19 groups was 36.4% and 15.6%, respectively. The prevalence of tricuspid regurgitation in MIS-C and COVID-19 groups was 62.8% and 34.6%, respectively. The prevalence of positive result for troponin enzyme level in MIS-C and COVID-19 groups was 24.2% and 7.4%, respectively. Conclusion: This study showed that the prevalence of cardiac involvement in MIS-C patients was greater than COVID-19 patients. Additionally, the most cardiac complications among these groups of patients were tricuspid regurgitation and mitral regurgitation.

Comparison οf Immune Responses Through Multiparametric T cell Cytokine Expression Profile Between Children With Convalescent COVID-19 Or Multisystem Inflammatory Syndrome (preprint)

The immunological pathways that cause Multisystem Inflammatory Syndrome after SARS-CoV-2 infection in children(MIS-C) remain under investigation. Aim of this study was to prospectively compare T-cell cytokine expression profile in unvaccinated children with acute MIS-C(MIS-C_A) before immunosuppression, convalescent MIS-C(one month after syndrome onset, MIS-C_C), convalescent COVID-19(one month after hospitalization) and healthy, unvaccinated controls. Intracellular expression of IL-4, IL-2, IL-17, IFN-γ, TNF-α and Granzyme B, post SARS-CoV-2-Spike antigenic mix stimulation of T cell subsets was analyzed by 13-colour Flow Cytometry. Twenty children with median age(IQR): 11.5(7.25-14) years were included in the study. From the comparison of the flow cytometry analysis of the 14 markers of MIS-C_A with the other 3 groups(MIS-C_C, post-COVID-19 and controls), significant differences were identified for: 1. CD4+IL-17+/million CD3+: 293.0(256.4-870.9) vs 50.7(8.4-140.5); P-value:0.03, vs 96.7(89.2-135.4); P-value:0.03 and vs 8.7(0.0-82.4); P-value:0.03, respectively, 2. CD8+IL-17+/million CD3+: 335.2(225.8-429.9) vs 78.0(31.9-128.9) vs 84.1(0.0-204.6) vs 33.2(0.0-114.6); P-value:0.05, respectively 3. CD8+IFN-γ+/million CD3+: 162.2(91.6-273.4) vs 41.5(0.0-77.4); P-value:0.03 vs 30.3(0.0-92.8); P-value:0.08, respectively. In children presenting with MIS-C one month after COVID-19 infection, T cells were found to be polarized towards IL-17 and IFN-γ production compared to those with uncomplicated convalescent COVID-19, a finding that could provide possible immunological biomarkers for MIS-C detection.

IFIH1 loss-of-function predisposes to inflammatory and SARS-CoV-2-related infectious diseases (preprint)

The IFIH1 gene, encoding melanoma differentiation-associated protein 5 (MDA5), is an indispensable innate immune regulator involved in the early detection of viral infections. Previous studies described MDA5 dysregulation linking it to weakened immunological responses, and increased susceptibility to microbial infections and autoimmune disorders. Monoallelic gain-of-function of the IFIH1 gene has been associated with multisystem disorders, namely Aicardi-Goutieres and Singleton-Merten syndromes, while biallelic loss of this gene causes immunodeficiency. In this study, nine patients suffering from different cases of recurrent infections, inflammatory diseases, severe COVID-19, or multisystem inflammatory syndrome in children (MIS-C) were identified with putative loss-of-function IFIH1 variants by whole exome sequencing. All patients revealed signs of lymphopenia and an increase in inflammatory markers, including CRP, amyloid A, ferritin, and IL-6. One patient with a pathogenic homozygous variant c.2807+1G>A was the most severe case showing immunodeficiency and glomerulonephritis. The c.1641+1G>C variant was identified in the heterozygous state in patients suffering from periodic fever, COVID-19, or MIS-C, while the c.2016delA variant was identified in two patients with inflammatory bowel disease or MIS-C. Expression analysis showed that PBMCs of one patient with a c.2016delA variant had a significant decrease in ISG15, IFNA and IFNG transcript levels, compared to normal PBMCs, upon stimulation with poly(I:C), suggesting that MDA5 receptor truncation disrupts the immune response. Our findings accentuate the implication of rare monogenic IFIH1 loss-of-function variants in altering the immune response, and severely predisposing patients to inflammatory and infectious diseases, including SARS-CoV-2 related disorders.

Age-Associated Weaker Immunity to Coronaviruses is Characteristic of Children that Develop Multisystem Inflammatory Syndrome following SARS-CoV-2 Infection (preprint)

We analyzed the antibody and cytokine responses of twenty-three patients with multisystem inflammatory syndrome of children (MIS-C) that appeared with a three-to-six-week delay following a mild or asymptomatic SARS-CoV-2 infection. These responses were compared to healthy convalescent pediatric COVID-19 patients approximately twenty-eight days after the onset of symptoms. Both groups had strong IgG responses to SARS-CoV-2 spike (S) and nucleocapsid (N) proteins, but the MIS-C patients had weaker antibody responses to certain epitopes in the SARS-CoV-2 S and N proteins and to the S and N proteins of endemic human coronaviruses (HCoV) compared to pediatric convalescent COVID patients. HCoV antibody reactivity was correlated with age. In contrast, MIS-C patients had elevated serum levels of several proinflammatory cytokines compared to convalescent COVID patients, including interleukins IL-6, IL-8, IL-18 and chemokines CCL2, CCL8, CXCL5, CXCL9 and CXCL10 as well as tumor necrosis factor alpha and interferon gamma. Moreover, many cytokine responses of MIS-C patients were positively correlated with antibody responses to the SARS-CoV-2 S, N, membrane and ORF3a proteins while pediatric convalescent COVID patient cytokine responses were more often negatively correlated with antibody responses to the S, N and ORF3a proteins of SARS-CoV-2.

Autopsy Proven Fatal COVID-19 Vaccine-Induced Myocarditis (preprint)

Background: COVID-19 vaccines have been linked to myocarditis which in some circumstances can be fatal. This systematic review aims to investigate potential causal links between COVID-19 vaccines and death from myocarditis using post-mortem analysis. Methods: We performed a systematic review of all published autopsy reports involving COVID-19 vaccination-related myocarditis through July 3rd, 2023. All autopsy studies that include COVID-19 vaccine-induced myocarditis as a possible cause of death were included, without imposing any additional restrictions. Causality in each case was determined by three independent reviewers with cardiac pathology experience and expertise. Results: We initially identified 1,691 studies and, after screening for our inclusion criteria, included 14 papers that contained 28 autopsy cases. The cardiovascular system was the only organ system affected in 26 cases. In 2 cases, myocarditis was characterized as a consequence from multisystem inflammatory syndrome (MIS). The mean and median number of days from last COVID-19 vaccination until death was 6.2 and 3 days, respectively. Most of the deaths occurred within a week from the last injection. We established that all 28 deaths were causally linked to COVID-19 vaccination by independent adjudication. Conclusions: The temporal relationship, internal and external consistency seen among cases in this review with known COVID-19 vaccine-induced myocarditis, its pathobiological mechanisms and related excess death, complemented with autopsy confirmation, independent adjudication, and application of the Bradford Hill criteria to the overall epidemiology of vaccine myocarditis, suggests there is a high likelihood of a causal link between COVID-19 vaccines and death from suspected myocarditis in cases where sudden, unexpected death has occurred in a vaccinated person. Urgent investigation is required for the purpose of risk stratification and mitigation in order to reduce the population occurrence of fatal COVID-19 vaccine-induced myocarditis.

Establishing thresholds for cytokine storm and defining their relationship to disease severity in respiratory viral infections (preprint)

Previous studies have identified cytokines associated with respiratory virus infection illness outcome. However, few studies have included comprehensive cytokine panels, longitudinal analyses, and/or simultaneous assessment across the severity spectrum. This, coupled with subjective definitions of cytokine storm syndrome (CSS), have contributed to inconsistent findings of cytokine signatures, particularly with COVID severity. Here, we measured 38 plasma cytokines and compared profiles in healthy, SARS-CoV-2 infected, and multisystem inflammatory syndrome in children (MIS-C) patients (n = 169). Infected patients spanned the severity spectrum and were classified as Asymptomatic, Mild, Moderate or Severe. Our results showed acute cytokine profiles and longitudinal dynamics of IL1Ra, IL10, MIP1b, and IP10 can differentiate COVID severity groups. Only 4% of acutely infected patients exhibited hypercytokinemia. Of these subjects, 3 were Mild, 3 Moderate, and 1 Severe, highlighting the lack of association between CSS and COVID severity. Additionally, we identified IL1Ra and TNFa as potential biomarkers for patients at high risk for long COVID. Lastly, we compare hypercytokinemia profiles across COVID and influenza patients and show distinct elevated cytokine signatures, wherein influenza induces the most elevated cytokine profile. Together, these results identify key analytes that, if obtained at early time points, can predict COVID illness outcome and/or risk of complications, and provide novel insight for improving the conceptual framework of hypercytokinemia, wherein CSS is a subgroup that requires concomitant severe clinical manifestations, and including a list of cytokines that can distinguish between subtypes of hypercytokinemia.

Lower-dose Intravenous Immunoglobulin Therapy for Geriatric Inflammatory Bowel Disease Accompanied by COVID-19 Multisystem Inflammatory Syndrome: a Case Report (preprint)

Background this article presents a noteworthy case of SARS-CoV-2-associated inflammatory bowel disease (IBD) in an elderly individual who endured three hospitalizations without favorable response to conventional treatment. Ultimately, the patient's symptoms subsided following the administration of intravenous immunoglobulin (IVIg).Case presentation : the patient, an elderly individual, experienced short-term fever and sore throat after encountering the COVID-19 pandemic. Despite receiving a three-dose inactivated COVID-19 vaccine, the patient tested positive for SARS-CoV-2 antigen and developed worsening symptoms, including diarrhea and recurrent fever. Initial antibiotic treatment for bacterial enteritis proved ineffective. Further evaluation, including endoscopy and pathology, confirmed the diagnosis of IBD with concurrent multisystem inflammatory syndrome (MIS) in adults. Following lower-dose IVIg administration, the patient's symptoms improved, with resolution of fever, diarrhea, and inflammation.Conclusions the case highlights the complexity of diagnosis and treatment in geriatric with IBD and MIS, emphasizing the importance of early intervention with IVIg. Further research is needed to explore the relationship between COVID-19 infection, MIS, and acute autoimmune diseases, as well as the efficacy of IVIg in these conditions.

Long-term outcomes of COVID-19 infection in children and young people: a systematic review and meta-analysis (preprint)

Background Children and young people (CYP) may experience prolonged symptoms following COVID-19, commonly termed "Long-COVID". The nature of this in CYP is unclear, as are the sequalae of acute COVID-19. We aimed to systematically synthesise evidence of the long-term outcomes of COVID-19 in CYP. Methods 13 databases were searched until January 2022. Inclusion criteria: Observational studies reporting outcomes occurring four-weeks or more after COVID-19 in children <18 years old. Exclusion criteria: Outcomes of Paediatric Inflammatory Multisystem Syndrome. Title, abstract and full text screening were conducted independently by two reviewers. Data extraction and risk of bias assessment was by one reviewer with independent verification. Critical appraisal tools appropriate for study type were employed. Results were narratively synthesised with meta-analysis to generate summary estimates of risk of prolonged symptoms in CYP. Findings 94 studies were included. 66 recruited from hospital settings, 8 recruited solely from community settings. >100 symptoms were reported, the most common being fatigue, headache and cognitive symptoms. Summary estimates of risk of prolonged symptoms were higher for hospital samples (31.2%, 95% CI 20.3% to 43.2%) than for community samples (4.6%, 95% CI 3.4% to 5.8). Sequalae including stroke, type-1 diabetes, Guillan-Barre syndrome, and persistent radiological or blood test abnormalities have been reported in CYP following COVID-19. Most studies reporting these are case reports / case series and quality of evidence is low. Interpretation Prolonged symptoms following COVID-19 in children are variable and multi-system. Rates in community samples are lower than hospital. There is limited data on other sequalae in CYP. Heterogeneity in diagnosis of COVID-19, symptom classification, assessment method and duration of follow-up made synthesis less secure. Funding HT, CB and GS have National Institute for Health and Care Research fellowships. RB, CM and VW are supported by the NIHR West Midlands Applied Research Collaboration. CM Is supported by the NIHR School for Primary Care Research Research in context panel Evidence before this study At the time of writing and to the best of our knowledge, the protocol for this systematic review was a novel endeavour to summarise the longer-term effects of COVID-19 in children and young people (CYP). At least three systematic reviews have since been published, summarising the symptom profile and prevalence of Long-COVID in CYP, but prevalence estimates vary widely and the evidence base remains uncertain. In addition, there is very limited information on other sequalae of COVID-19 in this population group. We searched thirteen electronic databases (MEDLINE, EMBASE, AMED, HMIC, CINAHLPlus, PsycINFO, Web of Science (Science Citation and Social Science Citation indicies), ASSIA, WHO COVID-19: Global literature on coronavirus disease, Cochrane COVID-19 study register, ProQuest Coronavirus research database, NDLTD and OpenGrey) up to January 2022 for any empirical study including search terms pertaining to longer term symptoms of COVID-19 in CYP (<18 years old). The quality of the studies was mixed. Results were analysed narratively for each objective, and random effects meta-analyses conducted to estimate risk of prolonged symptoms in CYP who have had COVID-19. Added value of this study This review adds to the evidence of the heterogeneity of prolonged symptoms following COVID-19 in CYP but importantly, stratifies risk of this by recruitment setting. We also synthesise evidence on broader sequalae of the acute infection in this CYP and longer-term effects in CYP with pre-existing conditions, which have not been considered in previous reviews. We purposefully included case studies and case series, to capture emerging patterns of outcomes, which may well be important in a novel condition with a rapidly increasing volume of publications. To our knowledge, this systematic review and meta-analysis is the most comprehensive to date. Implications of all the available evidence This review adds to the evidence that a substantial proportion of CYP do experience effects of COVID-19 that last longer than four-weeks, with the most frequently reported prolonged symptoms being fatigue, headache and cognitive symptoms. The proportion of CYP developing prolonged symptoms in children recruited from community setting was low, although this may translate to a large number of affected CYP at population level. There is a paucity of controlled studies and this limits confidence that prolonged symptoms are attributable to COVID-19. Sequalae including stroke, type-1 diabetes, Guillan-Barre syndrome, and persistent radiological or blood test abnormalities have been reported in CYP following COVID-19 but most studies reporting these are case reports / case series and quality of evidence is low. To develop treatment plans and interventions for affected CYP, further studies are needed to better characterise this condition and understand its impact on the lives of CYP and their families and communities. These should ideally recruit from community settings, include population-based control groups and consider using standardised definitions and outcome measures where possible.

The Role of Malnutrition on Outocomes of Multisystem Inflammatory Syndrome Due to Covid-19 in Children (preprint)

Background Malnutrition increases the complications and mortality in critically-ill children. A retrospective study was performed to define the role malnutrition on outcomes of multisystem inflammatory syndrome (MIS-C) due to COVID-19 in children.Methods Patients with MIS-C due to COVID-19 were evaluated for demographic features, anthropometric parameters, clinical findings and outcomes. Patients with z scores of body mass index (> 5 years-of-age) and weight-for-age (< 5 years-of-age) < -2 were considered as malnourished. Sarcopenia was defined by total psoas muscle area (tPMA), calculated on abdominal computed tomography (CT) at the level of L3 and L4 vertebrae. The z scores <- 2 for tPMA were considered as sarcopenia. The results of patients with (M+) and without (M-) were compared.Results Twenty-seven patients were included. Forty-four percent (n = 12) of patients had malnutrition. Malnutrition was classified as mild to moderate (1/3), severe (1/3) and overweight (1/3). Eighty-two cases had acute malnutrition. Among MIS-C symptom criteria, rash was significantly higher in M + children (p<0.05). Laboratory investigations showed higher ferritin levels in M + patients (p<0.05). The median tPMA and sarcopenia is significantly higher in M + when compared to M- group (42% vs 7%, p<0.05). The oral feeding time, complication rates and length of hospital stay were similar in both groups (p>0.05).Conclusion Children with MIS-C due to COVID-19 already have mild to severe malnutrition at admission. Rash and higher ferritin levels are more common in patients with malnutrition. In addition to anthropometric parameters, sarcopenia calculated using tPMA can be used to predict malnutrition in critically-ill children.

Characteristics and Outcomes of Multisystem Inflammatory Syndrome in Children: A Multicenter, Retrospective, Observational Cohort Study in Mexico (preprint)

Multisystem inflammatory syndrome in children temporally associated with coronavirus disease 2019 (MIS-C), a novel hyperinflammatory condition secondary to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is associated with severe outcomes such as coronary artery aneurysm and death. This multicenter, retrospective, observational cohort study including eight centers in Mexico, aimed to describe the clinical characteristics and outcomes of patients with MIS-C. Patient data were evaluated using latent class analysis to categorize patients into three phenotypes: toxic shock syndrome-like (TSSL)-MIS-C, Kawasaki disease-like (KDL)-MIS-C, and nonspecific MIS-C (NS-MIS-C). Risk factors for adverse outcomes were estimated using multilevel mixed-effects logistic regression. The study included 239 patients with MIS-C, including 61 (26%), 70 (29%), and 108 (45%) patients in the TSSL-MIS-C, KDL-MIS-C, and NS-MIS-C groups, respectively. Fifty-four percent of the patients were admitted to the intensive care unit, and 42%, 78%, and 41% received intravenous immunoglobulin, systemic glucocorticoids, and anticoagulants, respectively. Coronary artery dilatation and aneurysm were found in 5.7% and 13.2% of the patients, respectively. The rate of mortality due to SARS-CoV-2-related factors was 4.6%. Delay of [≥]10 days in hospital admission was associated with coronary artery aneurysm or dilatation (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.2- 2.0). Age [≥] 10 years (OR 5.6, 95% CI 1.4- 2.04), severe underlying condition (OR 9.3, 95% CI 2.8- 31.0), platelet count < 150,000/mm3 (OR 4.2, 95% CI 1.2- 14.7), international normalized ratio > 1.2 at admission (OR 3.8, 95% CI 1.05- 13.9), and serum ferritin concentration > 1500 mg/dL (OR 52, 95% CI 5.9- 463) were risk factors for death.

Does Nebulized Unfractionated Heparin Cause changes in derived neutrophil to lymphocyte ratios in severe COVID-19 pneumonitis? (preprint)

Background: COVID-19 a multisystemic disorder caused by the SARS-CoV-2 virus with deleterious and often fatal effects on respiratory function. Many therapeutic but expensive options have been presented. Unfractionated heparin is widely available and has been shown to have antiviral properties in vitro (by inhibiting the interaction of the spike protein of the coronavirus with ACE2), as well as anti-inflammatory, mucolytic and anticoagulant effects. Objective: To conduct a retrospective cohort study on COVID-19 patients admitted to an isolation ward in Jamaica to determine if nebulized unfractionated heparin delivered to patients with severe COVID-19 pneumonitis would influence the derived neutrophil to lymphocyte ratio (dNLR), a predictor of infection severity that was routinely measured. Methods: Study participants were hospitalized with COVID-19 pneumonitis, confirmed by polymerase chain reaction, between August 4, 2021 and November 13, 2021 and managed by anaesthesiologists. All had SpO2 < 92% on room air at admission. Patients received a standard COVID-19 care management protocol, as per the national guidelines of Jamaica. Seventeen patients with median (range)age 53 (35-67) years received nebulized unfractionated heparin (the study group); and seventeen patients with median (range) age 53 (38-67) years were not given nebulized unfractionated heparin (the control group). Derived neutrophil to lymphocyte ratios were observed daily over a 15-day period and tabulated and charted using stacked line graphs and box plots to compare changes in the variable between the groups. Results: The demographics and illness severity were comparable for the groups. Stacked line graphs of the  dNLR in each group indicated a more rapid decline in the group treated with nebulized unfractionated heparin than in the control group. Univariate analysis using box plots of serial dNLR changes showed larger interquartile ranges, longer whiskers, higher means and medians in the control group than in the study group. Conclusions: Participants treated with nebulized unfractionated heparin had a sharper decline in dNLR than patients who did not receive this therapy. There was a less varied, more predictable serial dNLR response in the study group than in the control group. Larger studies should explore the clinical implications of this finding.