Abstract The coronavirus disease (COVID-19), which is caused by a severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was for the first time detected in December 2019. At the beginning of the pandemic, it was believed that children are less susceptible to COVID-19 compared to adults, but further studies demonstrated that children are also susceptible to infection with the SARS-CoV-2 virus. In recent years, appeared studies about the role of genetic factors in the course of COVID-19. This fact suggests a possible existence of hereditary predisposition of individuals to infection with the SARS-CoV-2 virus. Recently, data was obtained that certain genetic polymorphisms (particularly, different genotypes for the polymorphic variant rs12979860 of the IFNL gene) can act as predictors of the severe course of respiratory infections in children (particularly, COVID-19). The aim of this work was to study the peculiarities of the genotype distribution for the IFNL gene rs12979860 polymorphism in a cohort of children who suffered from COVID-19 as well as to estimate the association of this polymorphism with a risk of infection with the SARS-CoV-2 virus, the development of pneumonia during the coronavirus disease, and the course of this disease among children with recurrent respiratory infections (RRI). For this purpose, genotyping for the IFNL gene rs12979860 locus polymorphism was carried out in the studied group of 70 children who had a laboratory-confirmed COVID-19. According to the results of the study, it was established that the C allele was more common in children with RRI as compared with those with episodic viral infections (p < 0.05, OR 3.2; CI 1.52–6.71); therefore, this variant can be considered as a risk allele for more frequent viral infections. In addition, the C allele predominated in the subgroup of children with pneumonia (p < 0.05, OR 2.36; CI 1.19–4.68), indicating that the C allele can be considered a risk allele for a more severe course of COVID-19 due to pneumonia. The results obtained suggest that the C allele can act as a predictive marker of the risk of developing pneumonia in children with COVID-19. In addition, the carriage of the C allele is associated with cases of RRI among children.
