An open, non-randomised, phase 1/2 trial on the safety, tolerability, and immunogenicity of single-dose vaccine “Sputnik Light” for prevention of coronavirus infection in healthy adults
Authors: Amir I. Tukhvatulin, Inna V. Dolzhikova, Dmitry V. Shcheblyakov, Olga V. Zubkova, Alina S. Dzharullaeva, Anna V. Kovyrshina, Nadezhda L. Lubenets, Daria M. Grousova, Alina S. Erokhova, Andrei G. Botikov, Fatima M. Izhaeva, Olga Popova, Tatiana A. Ozharovskaia, Ilias B. Esmagambetov, Irina A. Favorskaya, Denis I. Zrelkin, Daria V. Voronina, Dmitry N. Shcherbinin, Alexander S. Semikhin, Yana V. Simakova, Elizaveta A. Tokarskaya, Maksim M. Shmarov, Natalia A. Nikitenko, Vladimir A. Gushchin, Elena A. Smolyarchuk, Tatiana G. Zubkova, Konstantin A. Zakharov, Vasiliy B. Vasilyuk, Sergei V. Borisevich, Boris S. Naroditsky, Denis Y. Logunov, Alexander L. Gintsburg
Journal: The Lancet Regional Health - Europe (2021)

While the world is experiencing another wave of COVID-19 pandemic, global vaccination program is hampered by an evident shortage in the supply of licensed vaccines. In an effort to satisfy vaccine demands we developed a new single-dose vaccine based on recombinant adenovirus type 26 (rAd26) vector carrying the gene for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) glycoprotein - "Sputnik Light".We conducted an open label, prospective, non-randomised phase 1/2 trial aimed to assess safety, tolerability, and immunogenicity of "Sputnik Light" vaccine in a single center in Russia. Primary outcome measures were antigen-specific humoral immunity (Anti-RBD-SARS-CoV-2 antibodies measured by ELISA on days 1, 10, 28, and 42) and safety (number of participants with adverse events monitored throughout the study). Secondary outcome measures were antigen-specific cellular immunity (measured by antigen-dependent CD4+ and CD8+ T-cell proliferation, number of antigen-specific interferon-γ-producing cells as well as interferon-γ concentration upon antigen restimulation) and change in neutralizing antibodies (measured in SARS-CoV-2 neutralization assay).Most of the solicited adverse reactions were mild (66·4% from all vaccinees), few were moderate (5·5%). No serious adverse events were detected. Assessment of Anti-RBD-SARS-CoV-2 antibodies revealed a group with pre-existing immunity to SARS-CoV-2. Upon this finding we separated all safety and immunogenicity data based on pre-existing immunity to SARS-CoV-2. There were notable differences in the vaccine effects on immunogenicity by the groups. Vaccination of seropositive (N=14) volunteers rapidly boosted RBD-specific IgGs from reciprocal geometric mean titer (​GMT) 594·4 at a baseline up to 26899 comparing to 29·09 in seronegative group (N=96) by day 10. By day 42 seroconversion rate reached 100% (93/93) in seronegative group with GMT 1648. At the same time, in the seropositive group, seroconversion rate by day 42 was 92·9% (13/14) with GMT 19986. Analysis of neutralizing antibodies to SARS-CoV-2 showed 81·7% (76/93) and 92·9% (13/14) seroconversion rates by day 42 with median reciprocal GMT 15·18 and 579·7 in the seronegative and seropositive groups, respectively. Antigen-specific T cell proliferation, formation of IFNy-producing cells, and IFNy secretion were observed in 96·7% (26/27), 96% (24/25), and 96% (24/25) of the seronegative group respectively and in 100% (3/3), 100% (5/5), and 100% (5/5) of the seropositive vaccinees, respectively.The single-dose rAd26 vector-based COVID-19 vaccine "Sputnik Light" has a good safety profile and induces a strong humoral and cellular immune responses both in seronegative and seropositive participants.Russian Direct Investment Fund.