[Seroprevalence of anti S1 SARS-CoV-2 antibodies in workers vaccinated with Sputnik V at a public hospital in Buenos Aires].

The humoral immune response associated with both SARSCoV-2 infection and vaccination with Sputnik V in health workers, was analyzed.. A study was carried out in 660 health workers vaccinated with 2 doses of Sputnik V at the Vélez Sarsfield hospital, in the city of Buenos Aires, from December 2020 to April 2021. The objectives were to quantify anti-S1 SARS-CoV-2 IgG antibodies in vaccinated individuals and to determine clinical and pathological factors associated with that response. Samples were taken at least 21 days after the second vaccine dose. The mean age was 45 years (ES 0.44), 71.1% were women and 20.7% (n = 137) reported previous COVID-19 infection. IgG anti-spike (S) 1 SARS-CoV-2 antibodies were detected in 99.7% (n = 658) of the participants. The mean titer was 4197 ± 263.87 AU / ml (95 CI: 3679.1, 4715.3). The antibody response was higher in the group with prior COVID-19 disease vs. the group with no previous infection (10 693 ± 846.22 AU / ml vs. 2495.8 ± 187.98 AU / ml, p < 0.0001 in t-test). In a subgroup of 21 participants with high titers of anti-S1 IgG antibodies and with no apparent previous COVID-19, 11 individuals were positive for antibodies against the SARS-CoV-2 nucleocapsid. It is concluded that most of the vaccinated health workers developed antibodies and that those who had the disease prior to vaccination had higher antibody titers than those who did not have the disease.