Factors affecting the content of Ig G-antibodies to S-protein SARS-CoV-2 in the blood of reconvalescents after new coronaviral infection (COVID-19)

Abstract

Introduction. Morbidity and mortality of COVID-19 actualizes the identification of groups with the greatest risk of primary and re-infection, persons in need of priority vaccination or revaccination.Objective. To study the factors affecting the content of IgG antibodies to the S-protein SARS-CoV-2 in convalescents after suffering COVID-19 for 6 months.Materials and methods. The study of the Military Medical Academy and the Helix Laboratory Service was carried out from 06/01/2020 to 08/01/2021 on the basis of the Military Medical Academy and the Helix centers. The study included 1421 people – both sexes from 18 to 70 years old. 1205 with asymptomatic and mild disease (outpatient group). 216 with moderate or severe form (inpatient group). The outpatient group underwent a quantitative determination of IgG to the spike (S) protein SARS-CoV-2 by immunochemiluminescence analysis at 30, 45, 60, 90, 180 days from diagnosis. The diagnosis was verified by a positive RT-PCR result. The inpatient group underwent an identical study on the 1st, 14th, 45th, 60th, 90th and 180th days from the moment of admission to the hospital. The diagnosis was verified in the same way.Results. In convalescents, post-infectious immunity is formed from 30 days. Older age was associated with a more pronounced production of IgG to the S-protein SARS-CoV-2, mainly in older women. Moderate and severe course is characterized by higher concentrations of IgG to the SARS-CoV-2 S protein. A high level of IgG to the S-protein SARS-CoV-2 persists for up to 90 days, with a subsequent decrease by 180 days. Body weight, days of oxygen therapy, hyperthermia, the volume of lung tissue lesions and the level of C-reactive protein correlate with the concentration of IgG to the S-protein SARS-CoV-2. The use of glucocorticoids (GCS) is characterized by the presence of a higher concentration of IgG to the S-protein SARS-CoV-2 up to 6 months. There is a dose-dependent effect of using GCS.Conclusion. The formation and maintenance of the level of neutralizing antibodies for 6 months depends on the severity of the disease, the gender and age of the patients, and the fact of using GCS. This must be taken into account when carrying out therapeutic and preventive measures, planning vaccination.