Coronavirus disease (COVID-19), which was first recorded in China in December 2019, quickly spread to other countries and in a short period of time, the local outbreak escalated into a pandemic. There are significantly more cases of COVID-19 morbidity and mortality in European countries than in East Asia, where the disease was first detected. Such population differences are unique, especially for SARS-CoV-2 and are due to both socio-behavioral differences and features of the gene pool of the population of different countries. For infectious diseases, such as COVID-19, an important point is the genetic characteristics of individuals, which can determine its resistance or susceptibility to infection. Therefore, studies of the factors of hereditary predisposition to SARS-CoV-2 infection, as well as severity and mortality are extremely relevant. After genotyping among the healthy population of Ukraine and collecting relevant data from some European countries, we determined the correlation between morbidity, mortality from COVID-19 and the prevalence of genotype II (ACE1, I/D polymorphism) in the populations of Ukraine and several European countries. There was a negative correlation between the carrier of genotype II and susceptibility to SARS-CoV-2 infection per one million population ( R = –0.53, p < 0.05), so individuals with genotype II can be considered more resistant to infection SARS-CoV-2. Further study of the role of allelic variants of the ACE1 gene in the development of severity and complications affected patients of COVID-19, are promising for identified of genetic markers for development of personalized therapy.

Purpose - to study the features of vitamin D status and the effect of vitamin D3 supplementation on 25(OH)D in the serum of school-age children with COVID-19, taking into account the genotype of the rs2228570 polymorphism of the vitamin D receptor (VDR) gene. Materials and methods. The pilot, prospective, open-label study included 36 schoolchildren aged 9-16 who experienced asymptomatic (12 children) and mild / moderate (24 children) COVID-19. In all children were studied the content of 25(OH)D in blood serum and its dynamics under the influence of supplementation of 1000 IU per day for 12 weeks, taking into account the genotypes and frequency of distribution of alleles of the rs2228570 polymorphism of the VDR gene (26 children). Results. Children with asymptomatic COVID-19 were characterized by normal values of 25(OH)D (32.682.12 ng/ml). Children who underwent mild / moderate COVID-19 were probably more (41.7%) likely to have a state of hypovitaminosis vitamin D (27.362.12 ng/ml) and fewer children (58.3%) with an optimal level of 25(OH)D than children with asymptomatic disease. In 80.7% of the examined children, the genotype was determined by the rs2228570 polymorphism of the VDR gene, which includes the G allele with greater transcriptional activity of the VDR receptor. Supplementation of 1000 IU of cholecalciferol per day, regardless of 25(OH)D status and genotype for this polymorphism probably increased the supply of vitamin D in examined children with a tendency to increase 25(OH)D in children with genotype by polymorphism rs2228570 VDR gene, which includes allele G. Conclusions. Vitamin D deficiency can be considered as a risk factor for the symptomatic course of COVID-19 in children, which requires monitoring and correction of vitamin D status, the effectiveness of which can be determined by the genotype of the rs2228570 polymorphism of the VDR gene. Further studies of the role of vitamin D / VDR complex in the development and severity of COVID-19 in children will significantly expand the understanding of the pathogenetic relationship, to suggest and predict the effectiveness of personalized vitamin D supplementation regimens. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of all participating institutions. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Background. Studying COVID-19 prevalence among children is important for constant monitoring of the epidemiological situation, determination of the most vulnerable categories of children, and planning preventive measures. The aim of our research was a retrospective study of COVID-19 prevalence among children of Ukraine in 2020. Materials and methods. A retrospective study of COVID-19 prevalence among children from different regions of Ukraine was conducted, based on official statistical reports of the Ministry of Health of Ukraine. The prevalence of COVID-19 was measured as the number of cases per 100,000 children. Results. Among the population of Ukraine, children with confirmed SARS-CoV-2 infection amounted to 0.12 %, and among the children’s population of Ukraine — 0.7 %, while the prevalence rate reached 688.64. The incidence of COVID-19 among children in 2020 was highest in Kyiv, Chernivtsi, and Zaporizhzhia regions, and the lowest one was recorded in Kirovohrad, Luhansk, and Donetsk regions. In the age structure of Ukrainian children with SARS-CoV-2 infection, adolescents (63.8 %) prevailed. Conclusions. Adolescents were the age group of children most vulnerable to SARS-CoV-2 in Ukraine. The relatively low COVID-19 prevalence among children in Ukraine may be evidence of underdiagnosis due to insufficient coverage of laboratory testing for SARS-CoV-2 infection in the first year of the pandemic.

Коронавирусная болезнь 2019 (COVID-19) – острое инфекционное заболевание дыхательных путей, возбудителем которого является новый коронавирус 2 (SARS-CoV-2). COVID-19 поражает детей разных возрастных групп, даже новорожденных и детей до года. Не существует достоверных данных о факторах риска инфицирования SARS-CoV-2 у детей, хотя семейные случаи хорошо задокументированы. Большинство детей имеют более легкое клиническое те чение с такими распространенными симптомами, как лихорадка, кашель, слабость, миалгия, рвота и диарея. Увеличение маркеров воспаления и радиологические изменения менее распространены и выражены, чем у взрослых. Отсутствуют достоверные данные о связи отягчающих коморбидных состояний у детей и степени тяжести течения COVID-19. Coronavirus disease 2019 (COVID-19) is an acute infectious disease of the respiratory system caused by the new coronavirus 2 (SARS-CoV-2). COVID-19 affects children of all ages, even newborns and children under one year. There are no reliable data on risk factors of SARS-CoV-2 infection in children, although family cases are well documented. Most children have a mild clinical course with common symptoms such as fever, cough, fatigue, myalgia, vomiting, and diarrhea. Elevated markers of inflammation and radiological changes are less common and pronounced than in adults. There are no reliable data on the relationship between aggravating comorbid conditions in children and the severity of COVID-19.

No abstract