In phase 1 of the study, one dose of either rAd26 OR rAd5 was given and were assessed over 28 days for the safety of each component individually, with clinical and laboratory assessments on days 0, 2, and 14.  Participants' immune status was analyzed on days 0 and 28.  After concluding the safety of the individual components, phase 2 began and participants received the prime-boost vaccination (rAd26-S) on day 0 and the rAd5-S on day 21, undergoing assessments on days 0, 14, 28, and 42.  On days 0, 28, and 42, they assessed the immune status of the participants.  Volunteers were in hospital for the first 28 days from the start of vaccination and information on adverse events was recorded daily for both phases. To compare post-vaccination immunity with the natural immunity that forms during infection with SARS-CoV-2, they obtained convalescent plasma from blood samples of 4817 people from Moscow who had recovered after COVID-19.


Procedure:  Assessment of participants in phases 1 and 2

The vaccine, produced from vector components rAd26 and rAd5, was given to participants at a dose of 10^11 viral particles per dose for both components.  The frozen vaccine (Gam-COVID-Vac) has a volume of 0.5 mL per dose and the lyophilised vaccine (Gam-COVID-Vac-Lyo) must be reconstituted in 1.0 mL of sterile water for injection. Vaccines were all administered intramuscularly into the deltoid muscle.

Bowdoin College

Two phases (1 and 2) of open non-randomised studies at hospitals were performed in Russia. For each study, 120 healthy adult volunteers (aged 18–60 years) were preselected to be included in the volunteer register. Adult volunteers had a negative PCR and were negative when tested for IgG and IgM antibodies to SARS-CoV-2. Volunteers also had no history of COVID-19 or contact with patients with COVID-19.

Study Design and Participants

Logunov, D., Dolzhikova, I., et. al. "Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia."  The Lancet, vol 396, 4 Sept. 2020, pp. 887-897. https://doi.org/10.1016/S0440-6736(20)31866-3.


Safety and immunogenicity of an rAd26 and rAd5
vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non randomised phase 1/2 studies from Russia

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