Introduction. The global spread of SARS-CoV-2 coronavirus infection worldwide determines the need to study the clinical features, complications, extrapulmonary manifestations and long-term consequences of the infection in children. While many studies have been described in adult patients, there are limited data analyzing the clinical course of the disease in pediatric patients infected with SARS-CoV-2. Aim. Review of the literature containing currently reported cases of SARS-CoV-2 infection in children to present the state of the art, understand the direction of research and unresolved issues. Materials and methods. An analysis of publications containing data from studies of SARS-CoV-2 cases in children was carried out. Results. Researchers from different countries agree that children are less susceptible to COVID19. This can create a dangerous situation, which can lead to a weakening of attention to children. Although their clinical manifestations are mainly mild to moderate symptoms, nevertheless, severe cases of the disease occur in children, which can lead to death. Conclusion. The complexity and variability of COVID-19 manifestations support the hypothesis that further research is needed on the long-term and chronic symptoms of COVID-19 in children. Failure to understand the underlying biological mechanisms behind these persistent symptoms increases missed opportunities to identify patients at risk of chronicity in order to prevent such conditions and seek rehabilitation approaches for children with COVID-19.

Introduction. Asymptomatic transmission of the coronavirus poses a significant threat to efforts to reduce the incidence of COVID-19. A specific humoral immune response against SARS-CoV-2 can be induced in most symptomatic cases and in asymptomatic carriers. Determining the pattern of antibody response to SARS-CoV-2 infection in children can provide important information for improving screening and targeted protection of population that continue to suffer from this pandemic. Aim. To determine the level of antibodies to SARS-CoV-2 in children during the COVID19 epidemic. Materials and methods. Serum samples from 254 clinic patients from 1 to 17 years old, with an average age of 9.7±0.3 years, were studied by random selection. The analysis was carried out in 2 groups of patients: patients who underwent COVID-19 in the period from January 2021 to March 2022 with a positive SARS-CoV-2 PCR result (n=36) and a control group of children who deny the disease (n=218). IgM and IgG were determined in blood serum samples by means of ELISA using the SARS CoV-2-IgM and SARS CoV-2-IgG quantitative diagnostic kits (Vector-Best, Novosibirsk, Russia). Results. In the group of children who did not have COVID-19, negative results were detected in 25.2% of cases. IgG antibodies specific to SARS-CoV-2 were detected in 74.8% of patients, of which a low level of virus-neutralizing activity was found in 15.6% of patients, an average level in 20.2% of cases, and a high level in 39.0% of cases. In the group of children who had the disease, a low level of virus-neutralizing activity was detected in 29.4%, an average level in 32.4%, and a high level of IgG antibodies to SARS-CoV-2 was detected in 38.2% of cases. In the group of children who underwent COVID-19, 77.8% of the disease proceeded with symptoms of acute respiratory viral infections, 22.2% had CT signs of pneumonia, and there were no significant differences in the levels of specific antibodies. In the group of children who underwent COVID-19, 77.8% of the disease proceeded with symptoms of acute respiratory viral infections, 22.2% had CT signs of pneumonia, and there were no significant differences in the levels of specific antibodies. Analysis of seroprevalence in dynamics after the disease showed that the highest level of antibodies persisted for 2-4 months. after an illness. Conclusion. The proportion of asymptomatic forms of infection among children and adolescents is quite high. These undocumented infections often go unrecognized due to mild or absence of symptoms and, depending on their contagiousness and number of contacts, may play a significant role in the transmission of SARS-CoV-2. The findings raise important questions that should be explored in further studies regarding the role of serological tests in assessing the true extent of SARS-CoV-2 exposure in pediatric populations, as well as monitoring the response and duration of SARS-CoV2 antibody-mediated immunity.

Aim. Demonstration of the clinical case of pneumomediastinum in a teenager with severe COVID-19- associated pneumonia.Materials and methods. The clinical case of spontaneous pneumomediastinum was presented, which was a complication of the severe course of COVID-19 pneumonia in a teenager.Results. Patient Ch., 15 years old, with obesity of the 1st degree, was admitted to the hospital of infectious diseases for patients with a COVID-19 on the 7th day of the illness in a severe condition and had complaints of an increase in body temperature to 40ºC, pronounced cough and weakness, dyspnea when walking and at rest. The PCR test for SARS-CoV-2 gave a positive result. Multispiral computed tomography showed polysegmental interstitial lesion of both lungs, which had multiple areas of “ground glass”, signs of pneumomediastinum, subcutaneous emphysema of the upper third of the chest, left-sided pleural effusion. The volume of lung tissue lesion was 50% on the right and 85% on the left. The positive effect of treatment was not observed after 2-3 days in the hospital. The condition of heavy severity continued due to intoxication syndrome, respiratory failure, inflammatory changes in lung tissue syndrome. In this regard, the patient was injected intravenously with tocilizumab (Actemra®) 400 mg. The child was released on the 20th day of hospitalization with a positive clinical effect.Conclusion. The above clinical case demonstrates that in children a novel coronavirus infection can occur not only in severe form, but also with the possible development of complications in the form of pneumomediastinum and low effectiveness of antibacterial and antiviral therapy, which required the use of humanized monoclonal antibodies (tocilizumab).

Introduction. Features of the clinical course of bronchial asthma in children with obesity made it possible to identify a special phenotype, when the presence and severity of obesity determine a more severe course of asthma and a worse response to asthma therapy. Asthma, like obesity, is recognized as a classic example of multifactorial diseases, which are based on a rather complex gene network. Studying the genetic basis of both of these complex traits and linking them to the asthma phenotype should contribute to our understanding of the overall genetic basis of these pathological disorders.Aim. Evaluation of the clinical and genetic significance of the rs1801282 polymorphism of the PPARG2 gene (34C>G, p.Pro12Ala) in children with asthma and obesity.Materials and methods. 161 children with asthma were examined, including 59 patients with obesity 1-3 degrees. The examination included general clinical, functional, instrumental methods. The level of asthma control was determined according to the GINA criteria (2018). The study of gene polymorphisms was carried out by the real-time polymerase chain reaction.Results. An analysis of the frequencies of the PPARG2 gene polymorphism in children with bronchial asthma did not reveal any differences from the control group healthy people. In 61% of children with asthma and obesity, there was no control over the disease, which was associated with the G allele (OR 2.4 [95% CI: 1.09‒5.30], p=0.0281). An increase in the activity of lactate dehydrogenase and a decrease in the membrane potential of mitochondria in peripheral blood lymphocytes in children with the GG genotype were revealed, which may indirectly affect the level of disease control.Conclusion. The comorbidity of asthma and obesity in children affects the control of the disease. This manifests itself through immune mechanisms that play a key role in energy homeostasis and mitochondrial dysfunction of immunocompetent blood cells. The G-allele of the PPARG2 gene can be a marker of the lack of control over the disease in obese children with asthma. The pathogenetic significance of this polymorphism requires further study.