Evaluation of the Gam-COVID-Vac and Vaccine-Induced Neutralizing Response Against SARS-CoV-2 Lineage P.1 (Manaus) Variant in an Argentinean Cohort

Background: The safety, efficacy and humoral immune-response to Sputnik-V were independently evaluated. Since SARS-CoV-2 lineage P.1 is rapidly spreading in Argentina and the neutralization of P.1 by Sputnik-V-elicited sera has not been determined yet, we evaluated efficacy of Sputnik-V-immunized humoral response faced to P.1. Methods: The safety/efficacy of Sputnik-V were assessed by monitoring self-reported adverse events and disease rate among Health-Care Workers (HCW) who received both doses, within 4 months. Immunogenicity of the vaccine was evaluated by measuring anti-Spike (S) IgG antibodies (Abs) and neutralizing antibodies (NAb) prior to, 14 and 42 days after-vaccination. To determine the effectiveness of pre-existing NAb against P.1, samples were analysed from individuals: A-recovered from SARS-CoV-2 wild type B.1 (WT) infection, B-recovered from WT infection and received one/two doses of Sputnik-V, and C-without previous infection and received one/two doses of Sputnik-V. Findings: A total of 285 HCW were recruited, all reporting good tolerance, without severe adverse events. Sputnik showed 97·60% efficacy against COVID-19 during the observation period. At day 42, 99·65% of the individuals had anti-S IgG; however, 23·15% had not detectable NAb. The NAb ability against the SARS-CoV-2 strains showed significantly higher neutralization levels against WT compared to P.1 (p