The mechanisms of interaction between SARS-CoV-2, the causative agent of a new coronavirus infection (COVID-19), and the macroorganism, the formation of post-infectious and post-vaccination immunity are currently being actively studied and are the subject of fierce discussions not only in the scientific or medical community.

THE AIM

Of this work was to assess the significance of serological testing applied to patients with a new coronavirus infection COVID-19, depending on the clinical situation based on the experience of a practical laboratory.

MATERIAL AND METHODS

Type of study: retrospective observational. Three groups of patients were selected from 8.955 people: hospitalized with a diagnosis of COVID-19 (605 patients); undergoing examination before vaccination (454 patients), observed in dynamics after COVID-19 (135 patients). Serological testing was performed using commercially available test systems.

RESULTS

The serological profile and dynamics of the appearance of different classes of immunoglobulins were studied in patients hospitalized with a diagnosis of COVID-19. The time and kinetics of the formation of Ig of different classes distinguished — IgM was detected before, after and together with IgG and persisted for a long time. The dynamics of postinfectious immunity in 6—8 and 10—12 months after COVID-19 disease was evaluated. The concentration of IgG to S protein ranged from 1 to >200 BAU/ml.

DISCUSSION

Significant variability of the immune response was observed both in the case of the acute stage of a new coronavirus infection, and in the duration and level of the humoral response after the disease.

CONCLUSIONS

Taking into account the data of modern scientific research and the analysis of our practical experience, it can be assumed that before obtaining reliable clinical information about the «protection correlates» of post-infectious and post-vaccination immunity, serological testing has low clinical utility for the diagnosis and monitoring of a new coronavirus infection.