UDC 616.988:578.834-06:616.441-008.6`]-053.2

The problem of thyroid dysfunction related to S S-oV-2 infection remains unclear in children. Therefore, the study aimed to reveal the interrelationship between thyroid dysfunction and VID-19 severity as well as to determine optimal cut-off values for screening for thyroid disorders in children. A total number of 90 children aged from 1 month to 17 years were involved in the study. Patients with known thyroid disease were not recruited for the research. thyroid panel was assessed for all participants that included: free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH) and anti-thyroid peroxidase (ATPO) antibodies. Statistical analysis was done using the computer software Statistica 13.0. Research has revealed euthyroid sick syndrome (ESS) in 14.10% of SARS-CoV-2 infected children more often among patients with severe COVID-19 and multisystem inflammatory syndrome (33.33%) compared to mild COVID-19 course (6.67%) and moderate disease severity (8.89%) (P < 0.05). Significant correlation relationships were revealed for next values – FT3 and erythrocyte sedimentation rate (S) (rs = -0.22; P < 0.05); FT3 and Creactive protein ( P) (rs = -0.33; P < 0.05); FT3 and procalcitonin (rs = -0.43; P < 0.05). The next cut-off values for ESS determination were revealed: ESR 18.5 mm/h (AUC 0.803); CRP 11.5 mg/l (AUC 0.763); ferritin 84.8 ng/ml (AUC 0.733). Results suggest that pediatricians should pay attention to the endocrine disruptions by VID-19 in children. 

Introduction: There is evidence that high titers of diphtheria antibodies are more often associated with an asymptomatic or less severe course of COVID-19. The aim of the study was to determine the features of the COVID-19 course in school-aged children depending on the state of postvaccination immunity against diphtheria toxin.

Methods. In total, 90 children aged 6 to 18 years were examined: 60 patients with confirmed SARS-CoV-2 infection and 30 children without signs of the disease (control group). There were 20 patients with a mild COVID-19 course, 31 patients with moderate disease severity and 9 patients with severe disease severity. All children were tested for the level of immunoglobulin G (IgG) against diphtheria toxin by immune-enzymatic analysis.
Results. Total serum immunoglobulin G against diphtheria toxin was 0.431 (0.113; 0.828) IU/mL. Antitoxic immunoglobulin G was 2.5 times higher in children in the control group than in patients with SARS-CoV-2 infection. A decreased level of immunoglobulin G was associated with increased disease severity. In children with specific IgG 0.01-0.2 IU/mL revaccination is recommended; therefore, 4.2% of the children in the control group, 6.8% with a mild COVID-19 course, 50% with moderate disease severity and 100% of children with severe COVID-19 needed a booster dose of diphtheria toxoid. A moderate negative correlation was observed between the level of immunoglobulin G against diphtheria toxin and ESR (r=-0.38, p=0.004), CRP (r=-0.32, p=0.021), D-dimer (r =-0.35, p=0.009), duration of hyperthermia (r=-0.49, p=0.003), and duration of treatment (r=-0.43, p=0.012).
Conclusions. Children with manifested SARS-CoV-2 infection had significantly lower levels of immunoglobulin G against diphtheria toxin compared to the control group, indicating a lower level of humoral immunity. Children with a mild course of COVID-19 had a significantly higher level of specific IgG against diphtheria toxin than those with a moderate and severe disease course.

Abstract
Lyme disease is an infectious disease caused by bacteria of the Borrelia burgdorferi sensu lato (Bbsl) complex and is characterized by predominant lesions of the skin, cardiovascular system, nervous system and musculoskeletal system. We have described a clinical case of first- degree atrioventricular block in a 14-year-old boy caused by Lyme borreliosis. The disease started with the manifestations of cardiovascular system involvement. The patient and his parents did not recall observing a tick bite or manifestation of erythema migrans (EM). The boy was prescribed doxycycline. Three weeks after antibiotic therapy a second ECG examination was performed and showed no abnormalities.