The parameters of long-term humoral immunity induced by a single injection of the Sputnik Light vaccine among non-infected volunteers and those infected with SARS-CoV-2

Although the immunogenicity of clinically approved COVID-19 vaccines remains under intensive investigation, little is still known about the parameters of long-term immune responses. In this paper, we present for the first time the parameters of humoral immunity studied in the phase 1-2 open-label clinical trial of the Sputnik Light vaccine, with a special focus on late follow-up time points (90 and 180 days). For the most accurate assessment of the parameters of humoral post-vaccination immunity (titer and avidity index of antigen-specific antibodies against the RBD domain of SARS-CoV-2), we conducted an additional analysis that allowed us to triage volunteers with immunity formed only in response to vaccination, as well as those with hybrid immunity (infected with SARS-CoV-2 before and after vaccination). The findings indicate that single-shot vaccination with the Sputnik Light vaccine induces a durable (seroconversion 73% on day 180) and mature humoral immunity. Natural immunization as a result of the SARS-CoV-2 infection leads to significant changes in the studied parameters of post-vaccination immunity.