Supramolecular assemblies based on polyelectrolyte complexes made it possible to create complex interfaces with predictable properties. Polyelectrolyte complexes serve as a pseudo-liquid contact in ion-selective electrodes.

The pandemic of a new coronavirus infection in the world, including in Russia, was the basis for a detailed analysis of the disease features in children hospitalized in the only specialized hospital in Saint Petersburg. The purpose — is to analyze clinical and epidemiological data and approaches to the treatment of COVID-19 in children based on the functioning of the specialized infectious hospital, which was the first in such a megalopolis as Saint Petersburg to be deployed to work with the new coronavirus infection from January 2020 to the present. Material and methods. Based on a retrospective continuous single-center study, we analyzed 206 medical records of inpatient children aged 0 to 18 years who were treated in the Infectious Department № 7 of the Filatov municipal hospital № 5 in Saint Petersburg with a diagnosis of COVID-19 from March to June 2020. The mandatory selection criterion was laboratory confirmation of the COVID-19 diagnosis — a positive result of PCR of SARS-Cov-2 RNA in nasopharyngeal and oropharyngeal smears. The article is descriptive in nature. Results. It was found that children older than 3 years prevailed among the patients (71,5%, n = 147). Family contact with adults prevailed (54,9%, n = 113). COVID-19-ARVI was diagnosed in 81,4% (n = 168) of children, pneumonia was diagnosed in 18,6% (n = 38) of cases, and in 1,9% (n = 4) of cases it was asymptomatic. Mild forms of the disease prevailed (76,2%, n = 157), severe ones occurred only in 1,9% (n = 4) of patients. In 30,7% (n = 63) of cases, patients were admitted to a hospital late (in the second week of the disease). It was found that the clinical picture was dominated by fever (78,6%, n = 162), which lasted more than 5 days in 22,3% (n = 46) of cases, pharyngeal hyperemia — 84,5% (n = 174), cough — 51,2% (n = 105), symptoms of intestinal dysfunction — 19,4% (n = 40), anosmia — 9,9% (n = 20), exanthema — 7,8% (n = 16), sternal pain — 9,9% (n = 20). Recombinant interferon alpha-2b, umifenovir, lopinavir/ritonavir, anticoagulants, macrolides, and cephalosporins were used in the treatment of children. All patients showed positive dynamics with favorable outcome after treatment. All patients were discharged with clinical recovery. In 84,4% (n = 174) of patients sanation of nasopharynx и and fauces took place in hospital, in 62,1% (n = 128) of cases virus discharge took place on the 10–12 day, in other cases after 2–4 weeks. Conclusion. COVID-19 in children in a megalopolis has specific features compared with other ARVIs, but therapy principles are similar, implying taking into account the disease severity and early start of etiotropic treatment with the whole range of available antivirus drugs allowed for children and having an evidential basis, which was confirmed in the present research.

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.

Objective: To describe the burden of COVID-19 in a children’s multidisciplinary hospital for two years of the pandemic, taking into account of age, severity of the disease, the spectrum of underlying conditions and the intensive care need.Methods: An assessment of 6048 cases of COVID-19 in patients under 18 years of age hospitalized from March 26, 2020 to December 31, 2021 was carried out. The diagnosis was confirmed by PCR on an outpatient basis or after hospitalization with the help of diagnostic kits registered in the Russian Federation. The features of the work of a children’s multidisciplinary hospital in new conditions, the dynamics of hospitalization, age characteristics and new coronavirus (CV) infection severity in the pandemic development process are presented. The analysis of the underlying condition’s structure depending on the severity of the disease, as well as the need and volume of therapy in the intensive care unit. The frequency and main characteristics of children’s multisystem inflammatory syndrome (MIS-C) in hospital conditions, long-term PCR positivity and its effect on the duration of inpatient treatment of children have been established.Results: The spread of SARS-COV-2 in St. Petersburg required a radical change in the work of the children’s multidisciplinary hospital. During the two years of the pandemic, four waves of hospitalization of children with new CV were revealed, differing in duration, intensity, and frequency of lung damage, but having no significant differences in the proportion of severe forms of the disease (1.7-2.8% of cases). Intensive therapy was required in 3.6% of cases, of which only 1/3 was due to the severe course of COVID-19 with a lung lesion volume of up to 100%. In 1/3 of cases, patients had risks of developing severe forms and in 1/3 – other pathology. Severe course of new CV was significantly more often accompanied by the need for respiratory support, anticoagulants and anti-inflammatory therapy. Contributing factors of severe forms and unfavorable outcomes were: pathology of the central nervous system, genetic diseases and malformations, obesity, as well as chronic bronchopulmonary pathology. Mortality in the hospital was recorded only among children with severe underlying conditions (0.1% of cases). D-MVS was registered significantly more often in boys (7 out of every 10 patients), accounting for 1.2% of cases of hospitalization of children with new CV over the entire period. Convalescent PCR-positivity in the outcome of COVID-19 was detected in 1/3 of children, significantly more often during the autumnwinter waves of the pandemic and among patients of high school age.Conclusion: New CV is gradually strengthening its position in the structure of acute respiratory pathology in children. Some of SARS-COV-2 infection cases is accompanied by extensive lung damage, as well as severe systemic inflammation independently or in the other infectious diseases structure, induction of the debut of various somatic pathology is not excluded. The presented data confirm the need for increased attention at high risk of adverse respiratory diseases outcomes children. All severe cases of COVID-19 in children require a personalized approach, taking into account the existing background diseases and possible options for the progression of the process. MIS-C should be considered as a systemic inflammatory response syndrome within the framework of an infectious disease of various etiologies, differentiated with Kawasaki disease and the debut of systemic diseases. The long-term PCR-positivity in the outcome of COVID-19 requires further study to address the need and nature of therapy in order to prevent further spread of infection in the population.