Post-vaccination and post-infection humoral immune response to the SARS-CoV-2 infection

Introduction. Mass vaccination of the population against SARS-CoV-2 in Russia and abroad has been going on for more than 2 years. Various types of vaccines are used for vaccination (vector vaccines, RNA vaccines, whole-virion vaccines). The first in the world was registered the Russian vector vaccine «Gam-COVID-Vac» («Sputnik V»), which is widely used in our country, as well as in many other countries of the world. An important area of research is the monitoring of the parameters of the vaccine-induced immune response their analysis in relation to the characteristics of the immune response caused by SARSCoV-2 infection/COVID-19. Such studies are important both for assessing the intensity and duration of post-vaccination immunity, and for improving strategies for immunoprophylaxis and immunotherapy of coronavirus infection. The article presents the results of a study of the humoral immune response in patients with COVID-19 and vaccinated with «Sputnik V» in the period from autumn 2020 till the present time. The aim of the work - a comparative study of the humoral immune response to SARSCoV-2 infection and vaccination against COVID-19. Material and methods. The content of antibodies against SARS-CoV-2 S- and N-proteins was studied in 449 blood serum samples of men and women (age 25-65 years). 5 groups of samples were formed: suffered from COVID-19 of mild and moderate severity, at different times after recovery (262 samples);immunized with the «Sputnik V» vaccine, at different times after injection of the 2nd component of «Sputnik V» (104 samples);suffered from COVID-19 of mild and moderate severity, and then vaccinated with «Sputnik V» (53 samples);vaccinated with «Sputnik V», and then suffered with COVID-19 (12 samples);revaccinated with the vaccine «Sputnik Light» (18 samples). Results. To assess the content of IgG antibodies to S-protein and to N-protein of SARSCoV-2 in human blood sera, an EIA diagnostic system was developed further certified by the Ministry of Health of Russian Federation. In people suffered COVID-19 in 90 % of cases the positive levels of IgG antibodies to SARS-CoV-2 S-protein persist 9 months after recovery, while the proportion of potential plasma donors and material for obtaining intravenous immunoglobulin with a high content of IgG antibodies to S-protein 1 month after the disease is 20 %. In 76 % of people vaccinated with «Sputnik V» high levels of IgG antibodies to S-protein are detected within 6 months after the course of vaccination. The content of IgG antibodies to S-protein in the blood sera of persons suffered COVID-19, and then 6 months after recovery vaccinated with the 1st component of the vaccine «Sputnik V» in 100 % of cases was high with a positivity coefficient above 8.1, regardless of the initial value, already on 7 and 21 days after injection. In persons vaccinated with «Sputnik V» and then passed COVID-19, a high content of S-specific IgG antibodies is observed in 100 % of cases. The examination of vaccinated persons who underwent revaccination with «Sputnik Light» showed a 100 % high level of antibodies against S-protein. Conclusion. The developed test system may be suitable for assessing the content of IgG antibodies to SARS-CoV-2 antigens in COVID-19 patients, vaccinated and revaccinated. The performed study demonstrated that there is a intensive post-vaccination immunity for 6 months and post-infectious immunity for 9 months.