ABSTRACT
The medical community is interested in the duration of immune protection and the level of specific antibodies (AB) that can pre-vent reinfection with SARS-CoV-2. Objective. To perform a comparative evaluation of efficacy and immunogenicity of Gam-COVID-Vac and CoviVac vaccines against SARS-CoV-2 in a prospective observational study. Material and methods. The following vaccines were used for the vaccination of subjects (n=3322) aged 18 years and older: Gam-COVID-Vac - 1,622 (48.8%) subjects (group I), CoviVac - 1,700 (51.2%) subjects (group II). Vaccinated subjects were fol-lowed up for 6 study visits: before the 1st component of the vaccine, before the 2nd component of the vaccine, 42 days, 3 months, 6 months, and 12 months after the 1st component of the vaccine. Immunoglobulin G (IgG) levels of AB to S protein were compared after the injection of Gam-COVID-Vac and CoviVac vaccines using an enzyme immunoassay. Statistical processing of the obtained data was performed using IBM SPSS Statistics v. 24 and MedCalc v. 20.104 software. Results. Group I subjects showed an increase in specific AB (IgG) levels to SARS-CoV-2 S protein from visit 1 to visits 2 and 3 (p<0.05). In more extended follow-up periods (visits 5, 6), AB levels in groups I and II did not differ significantly and remained sufficiently high by visit 6. Within one year of follow-up, the incidence of COVID-19 (confirmed by polymerase chain reaction) was significantly (p<0.01) lower in the Gam-COVID-Vac group (group I): 22.2% vs. 45.2% in the CoviVac group (group II). The maximum number of days (p<0.05) before the COVID-19 infection was observed in those vaccinated with Gam-COVID-Vac (221 days) compared to those immunized with CoviVac (159 days). Conclusion. The Gam-COVID-Vac vaccine is more effective against COVID-19 and induces a more rapid response of the hu-moral immune system than the CoviVac vaccine. However, the duration of the humoral immune response after administration of Gam-COVID-Vac and CoviVac was similar. Copyright © 2022, Media Sphera Publishing Group. All rights reserved.