Modern methods of vaccination have confirmed their high effectiveness in fighting against the pandemic of a novel coronavirus infection. However, the use of various types of vaccines requires studying the effectiveness of the post-vaccination immune response (PIO), first of all, assessing the specificity and amount of production of antibodies to the surface and internal antigens of the SARS-CoV-2 virus, in particular, after the use of the most promising domestic vaccine Gam-Covid-Vac (Sputnik V). In particular, the data on the effectiveness of PVIR (increased antibody level) for the most promising domestic vaccine Gam-Covid-Vac (Sputnik V) need to be confirmed. It is also necessary to evaluate the effectiveness of the laboratory methods used for this purpose. To assess the effectiveness of PVIR, samples of biomaterial (blood serum) obtained on the 2225 day after inoculation of the second component of the vaccine from 202 Sputnik V-vaccinated, not preimmunized subjects, lacking antibodies to SARS-CoV-2 before vaccination, were examined. The levels of IgG and IgM antibodies to the surface and nucleocapsid antigens of the SARS-CoV-2 virus were determined using several semi-quantitative and quantitative methods and reagent kits from national and foreign manufacturers. To assess the diagnostic effectiveness of the methods, a comparative analysis of the specificity and sensitivity of all the laboratory methods used and a data correlation for various quantitative methods (using the Spearman correlation coefficient) between antibodies specific to the full-sized trimerized S-protein and the receptor-binding domain (RBD) of the SARS-CoV-2 S-protein were carried out. During the study, it was determined that all the reagent kits used to study IgG antibodies against SARS-CoV-2 S-protein and S-protein RBD showed maximum (100%) specificity in in the majority subjects (from 186 to 202 samples). The relevance of the data (comparative specificity), both for semi-quantitative and quantitative ELISA as well as for both ILA test systems regarding qualitative characteristics (positivenegative) was also close to the maximum magnitude (98.499.4%). A post-vaccination immune response during Sputnik V vaccination analyzing production of specific IgG antibodies was observed in 98.9% of all vaccinated subjects. IgG antibody range was studied to assess related protective level. Data are presented that a protective level of more than 150 BAU/мл was observed in 59.390.5% of the subjects, above 500 BAU/мл in 22.052.4% of the subjects, depending on the method used and the set of reagents. Based on the data obtained, it is concluded that all the methods and kits of reagents used, including domestically manufactured semi-quantitative tests, can be considered adequate to assess effectiveness of the post-vaccination immune response analyzing production of SARS-CoV-2-specific antibodies.
