Objectives: Diagnostic between multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C) and Kawasaki disease (KD) can make difficulties due to many similarities. Our study aimed to create a Kawasaki/MIS-C differentiation score (KMDscore) allowing discrimination of MIS-C and KD.Study design: The retrospective multicenter cohort study included clinical, laboratory, and instrumental information about MIS-C (n = 72) and KD (n = 147). The variables allowed to discriminate both conditions used to construct and validate the diagnostic score called the KMDscore.Results: Patients with MIS-C were older, had earlier admission to the hospital, had a shorter time before fever resolution, two times frequently had signs of GI and CNS involvement observed, and had more impressive thrombocytopenia, higher level of CRP, ferritin, ALT, AST, LDH, creatinine, triglycerides, troponin, and D-dimer compared to KD patients. Respiratory signs in MIS-C were presented with pleuritis, acute respiratory distress syndrome, oxygen dependency, lung infiltration, and ground-glass opacities in CT. The heart involvement with fast progression of myocarditis provided the severity of MIS-C and ICU admission due to 12 times higher arterial hypotension or shock and required cardiotonic. No differences in the frequency of CA lesions were seen in the majority of cases. Five criteria, CRP >11 mg/dl (18 points), D-dimer >607 ng/ml (27 points), age >5 years (30 points), thrombocytopenia (25 points), and GI involvement (28 points), were included in the KMDscore. The summa >55 points allowed to discriminate MIS-C from KD with a sensitivity of 87.5% and specificity of 89.1%.Conclusion: The KMDscore can be used to differentiate the diagnostic of MIS-C from KD.

ObjectivesHeart involvement in multisystem inflammatory syndrome associated with COVID-19 in children (MIS-C) is a new challenging problem, requiring fast and reliable diagnostics and appropriate treatment. The aim of this study is to describe heart involvement in patients with MIS-C.Study DesignIn this retrospective, multicenter cohort study, data of 122 patients were included. All patients met WHO and CDC criteria of MIS-C.ResultsVarious types of heart involvement in MIS-C patients were observed. Patients with solely coronary artery lesions (CAL, n = 10, 8.2%) had typical features of Kawasaki disease: younger age, thrombocytosis and normal ferritin level, without giant CA aneurysms, thrombosis, myocardial infarction, shock, and ICU admission. Patients with solely myocardial involvement (MI, n = 30, 24.6%) had an older onset age, elevated ferritin, LDH, the highest D-dimer, H score, and thrombocytopenia level. The following clinical signs were associated with MI: gastrointestinal and central nervous system disorder, sore throat, swelling face, splenomegaly, shock, and treatment in the intensive care unit required. Patients with a combination of CAL and MI (n = 10, 8.2%) had symptoms similar to patients with solely MI, except for impressive thrombocytopenia. Shock and ICU admission were found in 34.7% of patients without heart involvement (n = 72, 59%). One major criterion [troponin > 32 pg/ml (52 points)] or at least two minor criteria [face swelling (32 points) and D-Dimer > 1,300 ng/ml (29 points)] were associated with MI (>32 points) with a sensitivity of 67.5% and a specificity of 88.9%.ConclusionThe above-suggested criteria can be added to routine diagnostic procedures to confirm MI in MIS-C patients.

Objective: to identify the clinical, laboratory and epidemiological features of the new coronavirus (CV) infection in the provision of specialized medical care to children in the megalopolis of the Russian Federation. Methods: 674 cases of hospitalization of patients from birth to 17 years old inclusive with confirmed COVID-19 in the period from March 26 to June 26, 2020 in a children’s multidisciplinary hospital in St. Petersburg. Diagnostics of SARS-COV-2 in upper respiratory tract (URT) smears was carried out by PCR (a set of reagents for detecting RNA of coronavirus 2019-nCoV by PCR with hybridization-fluorescence detection “Vector-PCRRV-2019-nCoV-RG”). Patients underwent 4 (3; 5) repeated examinations depending on the diagnosis of the referral, as well as the duration of the convalescent virus carriage. The analysis of the severity of the course of the disease, the main clinical manifestations and their relationship with the development of pneumonia, as well as the epidemiological features of COVID-19 in children. The duration of inpatient treatment, outcomes and the need for intensive care are described. Changes in a number of laboratory parameters on analyzers made in the USA were assessed: a clinical blood test on a hematological one - Coulter UniCel (Beckman Coulter), a biochemical blood test on a biochemical one - Uni Cel DxC (Beckman Coulter), a coagulogram on a hemostasis analyzer (Instrumentation Laboratory). Results: Overall, there was a favorable course of COVID-19 in children. Intensive therapy was required only in 3.6% of cases with a total mortality rate of 0.15%, Kawasakilike syndrome was recorded in 0.3% of cases. In 1/3 of patients, prolonged viral shedding from the upper respiratory tract was detected. In children, intrafamilial infection from adults was in the lead; schoolchildren accounted for half of all hospitalizations. A distinctive feature of the new infection was mild clinical symptoms with fever and catarrhal symptoms up to 4/5 of cases, gastrointestinal symptoms - in every third patient. There were no significant differences in the severity of the disease by age. Pneumonia, diagnosed in ¾ cases by computed tomography, complicated the course in 13.1% of cases. The defeat of the lungs was accompanied by fever and dry cough, and in a more severe course: desaturation, chest pains, a feeling of insufficiency of inspiration. The age peaks of the incidence of pneumonia were revealed: at 4, 9, 12 years old and at the age of 17 years, the maximum (in 1/3 of cases). Laboratory changes were insignificant and quickly reversible. Conclusion: the course of COVID-19 in children in the megalopolis of Russia is comparable with foreign information. However, taking into account the experience of “Spanish ‘flu”, it is possible that in pediatric practice the number of severe forms and unfavorable outcomes may change in the near future, especially due to the difficulty of diagnosing Kawasaki-like syndrome and the need for a multidisciplinary approach to the treatment of such patients. Currently, the most vulnerable to the new CV are children with severe oncological, neurological and cardiovascular pathology, who have a rapid decompensation of the underlying disease against the background of COVID-19.