mRNA VACCINES INDUCES A HIGHER ANTIBODIES RESPONSE IN CHILDREN WITH PREVIOUS COVID-19

Background: mRNA vaccines elicit a durable humoral response to SARS-CoV-2 in adults, whereas evidence in children is lacking. This study aimed to evaluate the early and long-term immunological response after the BNT162b2 vaccine in children with or without a previous SARS-CoV-2 infection. Method(s): In a multicenter, prospective, observational study we profiled the immune response to the BNT162b2 vaccine in children aged 5-11 years attending the Pediatric Departments at the University of Padua and Bambino Gesu Children's Hospital in Rome (Italy). Forty-four healthy children (HC), 20 immune compromised (IC), and 18 children who previously developed MIS-C (MIS-C) were included in the study. Blood samples were collected pre-, 1, and 6 months after a 2-doses vaccination schedule. Neutralizing antibodies (NAbs) and anti-S-RBD IgG titers were analyzed through Plaque Reduction Neutralization Test (PRNT) and chemiluminescent immune-enzymatic assay (CLIA), respectively. B and T cell phenotypes were analyzed by flow cytometry. Geometric mean titers (GMTs) and 95% confidence intervals and median and interquartile range (IQR) of variables were evaluated according to pre-existing confirmed COVID-19. Result(s): Eighty-two children were studied;60 with a molecular-documented previous COVID-19 (Group A) and 22 without previous infection defined as the absence of antigen-specific antibodies before the vaccination (Group B). Overall, in Group A we observed higher NAbs GMTs, anti-S-RBD titers, and T- and B-reg cells than in Group A, at both 1 and 6 mo after vaccination (table);Nabs against the parental virus resulted to be greater in Group A than in Group B by a factor of 18 and 11, at 1 and 6 mo after vaccination, respectively. Both Groups recorded a decrease in antibody titers of approximately 50-70% between 1 and 6 months. A significant difference for Omicron NAbs (p=0.02) and anti-S-RBD (p=0.07) titers decay was observed between Group A and B;in contrast, Parental NAbs titers appeared to have similar trends in the 2 groups (p=0.47). Comparable antibody titers at 1 and 6 mo. (p=0.37) were detected across the three categories of HC, IC, and MIS-C (table). Conclusion(s): mRNA vaccination triggers a higher humoral response in children with a previous history of COVID-19, regardless of the immune deficiency or previous MIS-C, at least up to 6 mo, providing insight into boosting preexisting immunity with mRNA vaccines.

Early echocardiographic and cardiac MRI findings in multisystem inflammatory syndrome in children (MIS-C)

Introduction: Multisystem Inflammatory Syndrome in Children (MISC) is a known severe condition affecting children previously exposed to SARS-CoV-2. Cardiovascular manifestations in MIS-C are quite common and include myocardial dysfunction, coronary artery dilation or aneurysms, arrhythmias, conduction abnormalities, pericarditis and valvulitis. Severe cases can present even with cardiogenic shock. To date, little is known about the very early myocardial abnormalities in pediatric patients with MIS-C. The Speckle Tracking Echocardiography (STE) and cardiac MRI (cMRI) have shown to be potential candidate for identifying regional ventricular dysfunctions in early stages of inflammatory COVID-related conditions [1,2]. Objectives: To describe the early cardiac findings in patients with MIS-C, evaluated by two advanced cardiovascular imaging, STE and cMRI. Methods: Consecutive patients with MIS-C underwent standard transthoracic echocardiography (TTE), speckle-tracking echocardiography (STE) with analysis of left ventricle (LV) global longitudinal strain (GLS) and cardiac MRI (cMRI). Clinical and laboratory data, including markers of systemic inflammation, Troponin I (TnI) and Brain Natriuretic Peptide (BNP) were also collected at onset and during follow up. All patients received intravenous immunoglobulins (IVIGs), intravenous corticosteroids (methylprednisolone) and antiplatelet therapy (aspirin). The use of biological agents (Anakinra) was reserved to patients with severe or critical illness. The need for Intensive Care Unit (ICU) was based on clinical and hemodynamic status at presentation. Results: Twenty-three patients (13M, 10F), mean age 8.1±4years (range 5.4-15.7), all with positive clinical and/or serological evidence of previous SARS-COV2 infection, entered the study. The majority (78.2%) was caucasian. All presented high degree fever, gastrointestinal symptoms and rash. Conjunctivitis and cardiovascular symptoms, as hypotension, thoracic pain or dysrhythmia, were present in 10 (43.5%). Nine children (39.1%) shared Kawasaki Disease-like symptoms. Four patients (17.4%) needed ICU admission and 3 required inotropic support. Short-term survival was 100%. All patients showed an hyperinflammatory state with elevated CRP, ESR, and D-Dimer. Tn- I was abnormal (>34 ng/L) in 15 patients (65.2%), BNP was significantly elevated in 20 (86.9%). Median time to STE evaluation was 8 days and to cMRI was 18 days since fever onset. Mean LVEF and RVEF were respectively 59±10% and 45±7%. Coronary dilation was observed in 6 (26.1%) patients. STE showed reduced mean LVGLS (-17±4.3%). LVEF on cMR was 60±13%, LGE with non-ischemic pattern was evident in 6/16 patients (37.5%) and pericardial effusion in 2 (12.5%). Conclusion: MIS-C can occur in a small but not negligible proportion of children previously affected by COVID-19 and affects the heart in a significant proportion of them. STE and cMRI were shown to be very sensitive tools to evaluate and monitor the early cardiac dysfunctions in patients with MIS-C. The elevation of myocardial necrosis markers, the myocardial injury confirmed by reduced LVGLS and presence of LGE on cMR in about a quarter of the patients support the pathogenetic hypothesis of a post-viral immuno-mediated myocarditis.

PET-MRI for the detection of minimal residual disease in MIS-C: A long-term prospective study

Introduction: Multisystem Inflammatory Syndrome in Children (MISC) is an emerging clinical condition, similar to the hyperinflammatory response seen in adults with COVID-191. To date, little is known about the natural history of the disease and the long-term monitoring of MIS-C patients. Positron emission tomography PET/MRI is actually used to identify active inflammatory or neoplastic sites using [18F]fluorodeoxyglucose (FDG) due to the high glycolytic metabolism of inflammatory/neoplastic tissues2. Therefore, it could be indicated to evaluate and monitor the inflammatory disease state2. Objectives: To describe the PET/MRI findings for the evaluation of the minimal residual disease in a cohort of patients with MIS-C. Methods: Consecutive patients with MIS-C underwent a whole body FDG PET/MRI by 2 weeks, when possible, and at 6 weeks after the onset of fever. Each patient, after a 36 hours of fasting and high-fat low carbohydrate (<5g/day) diet preparation, was scanned using 3 MBq/kg FDG to minimize the radiation exposure. Clinical and laboratory data were also collected at onset and during follow up. Results: Ten patients (7M, 3F), mean age 10.2 years (range 5.4-17.7), all with positive clinical and/or serological evidence of previous SARS-COV2 infection, entered the study. All presented high degree fever, gastrointestinal symptoms and rash. Conjunctivitis and cardiovascular involvement, as hypotension, significant myocardial dysfunction and increased myocardiolysis markers, were also present in half of them. Only one patient needed intensive care support for five days. Systemic inflammatory and prothrombotic markers were elevated in all patients on admission (mean CRP 166.3 mg/L;procalcitonin 11.8 ug/L;D-dimer 2348 ug/L, ferritin 1135 ng/L). All patients were treated, 4.5 (± 1.5) days from fever onset with pulse IVIG (2 g/ kg) and IV methyprednisone (MPDN 2 mg/kg/day, max 80 mg) for 2 weeks then with oral PDN tapered down to 0 in further 4 weeks. PET/MRI was performed 13.3 days (± 1.5) after fever onset in three patients and 48 days (± 10.6) in 8. During the acute phase, all patients showed pelvic effusion and edema of the abdominal wall tissues at the total body MRI, not seen in patients during the late phase. Lymph node involvement was present in 81% of MRI findings. The cervical district appeared to be the most involved one as compared to the thoracic, mesenteric and retroperitoneal ones (72% vs 45, 36 and 45% respectively). However, a residual mesenteric lymphadenopathy was exclusive to the late phase (5/8 patients). Conclusion: PET/MRI confirms the good metabolic response to treatment in patients with MIS-C. The abdominal region is more intensively involved in the early stage of the disease, likely related to the hyperinflammatory state. A slow normalization through the lymph node compartment is present in the late stage. PET/MRI is a highly sensitive and specific tool for assessing minimal residual disease in MIS-C and should be indicated for patients with incomplete clinical response to treatment.

Pediatric systemic multi-inflammatory diseases in Italy during SARS-COV-2 epidemic: From Kawasaki disease to Kawacovid

Introduction: Italy was affected by the SARS-CoV-2 epidemic after its outbreak in China. With a 4-weeks delay after the peak in adults, we observed an abnormal number of patients with characteristics of a multi-inflammatory disease and similarities with Kawasaki Disease (KD). Others reported similar cases, defined PIMS-TS or MIS-C.1,2 Objectives: To better characterize clinical features and treatment response of PIMS-TS and to explore its relationship with KD. Methods: We conducted an observational, retrospective, multicenter study. On April 24th-2020 the Rheumatology Study Group of the Italian Pediatric Society launched a national online survey, to enroll patients diagnosed with KD or with a multisystem inflammatory disease between February 1st 2020 and May 31st. The population was then divided into two different groups: 1) Classical and incomplete KD, named Kawasaki Disease Group (KDG);2) KD-like multi-inflammatory syndrome, named KawaCOVID (KCG). An expert panel of pediatric rheumatologists re-analyzed every single patient to ensure appropriate classification. Data were collected with an online database. Results: 149 cases were studied, 96 with KDG and 53 with KCG. The two population significantly differed for clinical characteristics (see table 1). Lymphopenia, higher CRP levels, elevated Ferritin and Troponin-T characterized KCG such as lower WBC and platelets (all p values<0,05). KDG received more frequently immunoglobulins (IVIG) and acetylsalicylic acid (ASA) (81,3% vs 66%;p=0.04 and 71,9% vs 43,4%;p=0.001 respectively) as KCG more often received glucocorticoids (56,6% vs 14,6%;p<0.0001). SARS-CoV-2 assay more often resulted positive in KCG than in KDG (75,5% vs 20%;p<0.0001). Short-term follow data on KCG showed minor complications while on KDG a majority of patients had persistence of CAA. Comparing KDG with a KD-Historical Italian cohort (598 patients), no statistical difference was found in terms of clinical manifestations and laboratory data between the two groups Conclusion: Our study would suggest that SARS-CoV-2 infection might determine two distinct inflammatory diseases in children: KD, possibly triggered by SARS-CoV-2, and PIMS-TS. Older age at onset and clinical peculiarities, like the occurrence of myocarditis, characterize this multiinflammatory syndrome. Our patients had an optimal response to treatments and a good outcome, with few complications and no deaths.

Severe cardiac involvement with myocardial dysfunction and arrhythmias in SARS-COV-2-related Kawasaki-like disease

Introduction: During SARS-COV-2 pandemic, different reports have been published regarding children who developed hyperinflammatory syndrome with certain or probable relationship with SARS-COV-2. These patients presented incomplete or atypical manifestations of Kawasaki disease (KD), particularly abdominal pain, myocarditis and macrophage activation syndrome features. Objectives: To report a case of SARS-COV-2-related Kawasaki-like disease with severe cardiac involvement. Methods: case report description. Results: A 10-year-old previously healthy girl presented progressively worsening abdominal pain, high grade fever for 3 days and vomiting. Lab tests showed WBC 11680/mmc, N 9370/mmc, Creactive protein (CRP) 329 mg/L, procalcitonin (PCT) 0,74 ug/L, PT-INR 1,35 and elevated D-dimer and fibrinogen levels (817 ug/L and 9,45 g/L respectively). Abdomen ultrasound revealed lymphadenopathies and hyperechogenic mesentery in the right lower quadrant, although the appendix was not visualized. She underwent laparoscopy showing moderate quantity of free fluid and appendectomy was performed. Thereafter she continued to complain of high-grade fever, abdominal pain and diarrhoea, despite broad-spectrum antibiotics. Blood, urine and stool cultures were negative. Bilateral non-exudative conjunctivitis was present. Moreover, the lab tests showed persistent marked elevation of CRP (370 mg/L), WBC 15590/mmc, N 14070/mmc, hypoalbuminemia (23 g/L), elevated ferritin and triglycerides (458 ug/L and 221 mg/dl). By taking into consideration the concomitant SARS-COV-2 pandemic, nasopharyngeal and rectal swabs were taken with negative results. Conversely, serological test showed anti-SARS-COV-2 IgG antibodies and absence of IgM. The family medical history showed that the mother had presented fever, cough, ageusia and anosmia one month before, preceded by a contact with a SARS-COV-2 positive case, while the patient was asymptomatic at that time. Suspecting a KD-like disease she was referred to our Paediatric Rheumatology Unit: cardiological assessment revealed negative Twaves in V4-V5-V6 on EKG while standard and advanced echocardiography showed mild mitral and tricuspid insufficiencies, mild dilatation of the left main coronary artery (LMCA, z score +2), normal global function (FEVS 2D 58%) but reduced longitudinal strain (GLS-16%). Lab tests confirmed myocardial injury with troponin (TnI) 100,1 ng/l and brain natriuretic peptide (P-BNP) 593 ng/L. A single infusion of intravenous immunoglobulin 2 g/kg associated with methylprednisolone (1 mg/kg/day) led to a rapid clinical improvement with apyrexia and resolution of abdominal pain and conjunctivitis. Blood test confirmed gradual normalization of inflammatory markers, ferritin, troponin and BNP and EKG showed positive T-waves. Shortly after the discharge, while she was on prednisone 0.5 mg/kg/day and acetylsalicylic acid 100 mg/day, she referred some episodes of heart pounding, lasting about ten minutes with spontaneous resolution. Three weeks after onset, cardiac MRI was normal, however, speckle tracking echocardiography showed persistent dilatation of LMCA and reduction of global longitudinal strain (GLS-14%). 24-hour EKG-Holter detected episodes of supraventricular tachycardia and several ventricular and supraventricular extrasystoles. Thus, oral atenolol therapy was started. Conclusion: In our patient SARS-COV-2 induced a possible postinfectious antibody or immune-complex mediated reaction that led to KD-like disease with acute surgical abdomen presentation and persistent myocardial damage and arrythmias. Speckle tracking echocardiography appears more reliable than MRI in early detection of myocardial damage in patients with preserved left ventricular ejection fraction.

Life-threatening macrophage activation syndrome with fulminant myocarditis successfully rescued by high dose intravenous Anakinra

Introduction: Macrophage activation syndrome (MAS) is a rare, potentially life-threatening complication of some rheumatologic diseases1. Objectives: We report the case of a child with systemic onset Juvenile Idiopathic Arthritis (sJIA) complicated by severe MAS and acute myocarditis, needing veno-arterial Extracorporeal Membrane Oxygenation (VA-ECMO), successfully rescued by high dose intravenous Anakinra (HDIV-ANA). Methods: Case report's description Results: A two-year-old boy presented with one month history of fever associated with limping gait, cervical lymphadenopathy and skin rash. Laboratory tests showed elevation of inflammatory markers and ferritin. By exclusion criteria, sJIA was diagnosed and steroid therapy started. After a soft tissue bacterial infection, fever relapsed and laboratory tests were consistent with MAS (day 1): Hb 8.5 g/dL, PLT 44000/mm3;FDP 1522 ug/L, CRP 100 mg/L, ferritin 2200 ug/L. High doses intravenous metilprednisolone and oral Cyclosporin A (CSA) were started. On day 2 he presented a Systemic Capillary Leak Syndrome and acute myocarditis. He was admitted into the pediatric intensive care unit (PICU) where intravenous immunoglobulin and subcutaneous Anakinra (ANA) were added. On day 4, due to an episode of cardiac arrest, VA-ECMO was started and we tried high dose intravenous ANA (HDIV-ANA, 8 mg/Kg/day q6h). This treatment brought immediate benefit: echocardiography showed progressive resolution of myocarditis so that VA-ECMO was definitely weaned off in six days. Laboratory test showed isolated neutropenia (PMNs 0-100/mm3). Suspecting a iatrogenic cause, HDIV-ANA was gradually reduced to the maintenance dose without benefit. On day 22, ANA was stopped and neutropenia resolved. Analysis of PRF1 gene revealed a mutation (c.[272C>T] p.[Ala91Val]) in heterozygosis. 49 days after admission he was discharged on oral prednisone and CSA. Neither neurological nor other organ consequences related to MAS were reported. A few months later, on tapering down of therapy, he relapsed. ANA was restarted with rapid improvement and no side effects, including neutropenia. Currently, after 12 months, the disease is in clinical remission on medication. Conclusion: MAS is a rare life-threatening complication of sJIA, triggered by infections in up to one-third of the patients 2. It is the result of a cytokine storm that lead to a dysregulated inflammatory activation of the immune system, with rapid progression to multiorgan failure. Treatment usually includes high dose corticosteroids and immunosuppressive agents. Recently, the use of selective cytokine inhibitors has been suggested. No standardized guidelines are available to date, but the use of ANA has been already reported, pointing out the need for a higher doses regimen in refractory cases. MAS in our patient appeared after a soft tissue infection which could have act as triggering factor in a patient with sJIA and genetic predisposing pattern. The choice of intravenous administration of ANA was partly due to the generalized edema and partly to the severe discoaugulopathy. Considering the higher doses needed for rapidly suppressing the cytokine storm and ANA pharmacokinetics, we split the daily dose into four administrations. No major adverse events were reported, except for a transient neutropenia, already reported 6. Based on our experience, HDIV-ANA is a safe and effective treatment for refractory life-threatening sJIA-related MAS. This therapeutic approach may be also considered in the current pandemic COVID-19 emergency where recent evidence showed IL1-driven MAS-like complication triggered by SARS-COV-2 virus as predictor of bad outcome7.