Immunoglobulin G antibody response to the Sputnik V vaccine: previous SARS-CoV-2 seropositive individuals may need just one vaccine dose

Abstract

\n Introduction\n . Serology tests play an important role in assessing the immune system s response to a previous SARS-CoV-2 infection or to vaccination. In Venezuela, before and after receiving the Sputnik V vaccine, we evaluated the IgG antibody response against the nucleocapsid protein (NP) and the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 in a cohort of 86 individuals.\n \n Methods\n . Antibody responses against NP and RBD were determined with an ELISA just before, 3 weeks after the first and 6 weeks after the second dose of the vaccine.\n \n Results\n : Before vaccination, 59 individuals were seronegative and the other 27 were seropositive for SARS-CoV-2 antigens NP and/or RBD. Of the seronegative cohort, 42% did not develop a measurable IgG immune response against RBD after the first vaccine dose but all (100%) had a strong IgG response after two vaccine doses. All seropositive individuals developed a strong IgG antibody response against RBD after the first vaccine dose, with antibody levels approximately 40% higher than the seronegative individuals who had received two doses. Moreover, the previously seropositive subjects showed no significant increase in IgG antibody response against RBD after the second vaccine dose.\n \n Conclusions\n : We demonstrated that two dose of the Sputnik V vaccine triggers antibody response in all individuals of this study. The second vaccine dose of Sputnik V has no impact on the IgG response for who were seropositive for SARS-CoV-2 antigens prior to vaccination.\n