Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia

Abstract

Background A heterologous recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac (Sputnik V), showed a good safety profile and induced strong humoral and cellular immune responses in participants in phase 1/2 clinical trials. Here, we report preliminary results on the efficacy and safety of Gam-COVID-Vac from the interim analysis of this phase 3 trial. Methods We did a randomised, double-blind, placebo-controlled, phase 3 trial at 25 hospitals and polyclinics in Moscow, Russia. We included participants aged at least 18 years, with negative SARS-CoV-2 PCR and IgG and IgM tests, no infectious diseases in the 14 days before enrolment, and no other vaccinations in the 30 days before enrolment. Participants were randomly assigned (3:1) to receive vaccine or placebo, with stratification by age group. Investigators, participants, and all study staff were masked to group assignment. The vaccine was administered (0·5 mL/dose) intramuscularly in a prime-boost regimen: a 21-day interval between the first dose (rAd26) and the second dose (rAd5), both vectors carrying the gene for the full-length SARS-CoV-2 glycoprotein S. The primary outcome was the proportion of participants with PCR-confirmed COVID-19 from day 21 after receiving the first dose. All analyses excluded participants with protocol violations: the primary outcome was assessed in participants who had received two doses of vaccine or placebo, serious adverse events were assessed in all participants who had received at least one dose at the time of database lock, and rare adverse events were assessed in all participants who had received two doses and for whom all available data were verified in the case report form at the time of database lock. The trial is registered at ClinicalTrials.gov ( NCT04530396 ). Findings Between Sept 7 and Nov 24, 2020, 21 977 adults were randomly assigned to the vaccine group (n=16 501) or the placebo group (n=5476). 19 866 received two doses of vaccine or placebo and were included in the primary outcome analysis. From 21 days after the first dose of vaccine (the day of dose 2), 16 (0·1%) of 14 964 participants in the vaccine group and 62 (1·3%) of 4902 in the placebo group were confirmed to have COVID-19; vaccine efficacy was 91·6% (95% CI 85·6–95·2). Most reported adverse events were grade 1 (7485 [94·0%] of 7966 total events). 45 (0·3%) of 16 427 participants in the vaccine group and 23 (0·4%) of 5435 participants in the placebo group had serious adverse events; none were considered associated with vaccination, with confirmation from the independent data monitoring committee. Four deaths were reported during the study (three [<0·1%] of 16 427 participants in the vaccine group and one [<0·1%] of 5435 participants in the placebo group), none of which were considered related to the vaccine. Interpretation This interim analysis of the phase 3 trial of Gam-COVID-Vac showed 91·6% ...

Target Product Profile Analysis of COVID-19 Vaccines in Phase III Clinical Trials and Beyond: An Early 2021 Perspective

“…Four groups (Astra Zeneca/University of Oxford (AZ/Ox), CanSino Biologics, Gamaleya Research Institute and Johnson & Johnson/Janssen (J&J)) have all adopted the use of non-replicating adenoviral vectors to drive the expression of the full-length SARS-CoV-2 spike glycoprotein (5 × 10 10 or 10 11 viral particles for each dose injection) to induce an immune response [18,19,[25][26][27][28][29][30][31]. The differences between them lie in the chosen vector strain and immunization schedules.…”

“…CanSino (Ad5-nCoV) uses a recombinant version of Ad5 ad-enovirus that naturally transmits in humans [28,29], while J&J (Ad26.COV2.S) uses a variant adenovirus Ad26 that is not normally (or only rarely) encountered by the human population [31]. Gamaleya (Sputnik V) uses a combination prime with Ad26 and boost with Ad5 [19,30]. From 12-40,000 + have been enrolled in Phase III trials for each of the four members of this platform.…”

“…GMT measured by microneutralization assay using SARS-CoV-2 (hCoV-19/Russia/Moscow_PMVL-1/2020) with 50% tissue culture infective dose (TCID50) of 100. Data extracted from Figures 2C and 2D in reference [30] and from reference [19]. w Pre-immune sera.…”

“…The pandemic of 2020 caused by the global dissemination of the SARS-CoV-2 coronavirus has crippled the world. Tens of millions of infections and over two million deaths (https://coronavirus.jhu.edu/map.html [accessed 9 February 2021]) from coronavirus disease 2019 (COVID- 19) have given rise to sorrow, social isolation, and disruption of life as we know it. An immense body of the literature has been accumulating in the past year explaining the epidemiology and infectious mechanisms of SARS-CoV-2, the pathogenesis of COVID-19, and the development of potential therapies and vaccines [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”

SARS-CoV-2 transmission, vaccination rate and the fate of resistant strains

“…Vaccines are among the most effective public health measures against infectious disease 1 . Their track record brings hope that SARS-CoV-2 may soon be under control 13 as a consequence of a plethora of vaccine development efforts [14][15][16][17] . A potential cause of concern is the low rate of vaccine production and administration 18 coupled with reports of new strains with higher transmission rates 3,4,19 and even with potential for some degree of vaccine resistance 5,6,8,20 .…”