Sputnik V vaccine elicits seroconversion and neutralizing capacity to SARS-CoV-2 after a single dose

Massive vaccination offers great promise for halting the global COVID-19 pandemic. However, the limited supply and uneven vaccine distribution create an urgent need to optimize vaccination strategies. We evaluate SARS-CoV-2-specific antibody responses after Sputnik V vaccination of healthcare workers in Argentina, measuring IgG anti-spike titers and neutralizing capacity after one and two doses in a cohort of naive or previously infected volunteers. By 21 days after receiving the first dose of the vaccine, 94% of naive participants develop spike-specific IgG antibodies. A single Sputnik V dose elicits higher antibody levels and virus-neutralizing capacity in previously infected individuals than in naive ones receiving the full two-dose schedule. The high seroconversion rate after a single dose in naive participants suggests a benefit of delaying administration of the second dose to increase the number of people vaccinated. The data presented provide information for guiding public health decisions in light of the current global health emergency. [Display omitted] First dose of Sputnik V results in 94% seroconversion rate in naive individualsA second dose greatly increases antibody titers and neutralizing capacityOne dose in seropositive individuals elicits higher titers than two doses in naiveThere is no evident benefit of using a second dose in previously infected individuals Rossi et al. provide data on antibody responses to Sputnik V vaccine in naive and previously infected volunteers. This study shows a high seroconversion rate following the first dose in naive individuals. In seropositive participants, a single dose of Sputnik V elicits a fast and robust antibody response without apparent benefit from a second dose.