Despite the fact that the new coronavirus infection in children proceeds much milder than in adults, the pediatric practice is facing a problem associated with the general concept of «post-COVID conditions», including Multisystem Inflammatory Syndrome in Children (MIS-C) associated with COVID-19 and a complex of disease processes with various manifestations, united by the concept of postacute consequences of treatment or hospitalization for SARS-CoV-2 infection (PASC). The article describes a clinical case of combined post-COVID syndrome, in the form of a MIS-C and the subsequent development of PASC in the form of long-term recurrent urticarial rash elements in a 10-year-old child, simulating reactions similar to serum sickness and chronic urticaria.