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

The methods used in the phase 1/2 studies evaluating the safety and immunogenicity of the rAd26 and rAd5 vector-based COVID-19 vaccine consisted of three main components: the study design and participant selection, clinical procedures, and statistical analysis.

Bowdoin College

Emory University

Google

From our Literary Review:

With the aid of the Ministry of Health of the Russian Federation, russian researchers developed a vaccine composed of two distinct adenovirus vector components: recombinant adenovirus type 26 (rAd26) and recombinant adenovirus type 5 (rAd5), each of which had been previously tested separately in clinical trials at Johnson and Johnson (USA) and at the CanSino Biological/Beijing Institute of Biotechnology (China), respectively.  The rAd26/rAd5 vaccine was developed and tested in healthy participants in phase 2 clinical trials after confirming the safety of the two individual vector components in phase 1. They ultimately found  that this heterologous vaccine is safe and immunogenic in healthy adults, but that further investigation is still needed to understand its effectiveness.

******
Study on safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19

Investigates the safety and immunogenicity of a heterologous COVID-19 vaccine with two vector components: recombinant adenovirus type 26 (rAd26) and recombinant adenovirus type 5 (rAd5), both of which carry the gene for the SARS-CoV-2 spike glycoprotein S.  This vaccine was developed in two formulations, frozen and lyophilized, and tested in healthy participants after confirming the safety of the two individual vector components in phase 1.  They ultimately find that this heterologous vaccine is safe and immunogenic in healthy adults, but that further investigation is still needed to understand its effectiveness.

- Methods

- Results

- Discussion
  
       
       

rAd26 and rAd5 vector-based Vaccine


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

-  They find that the rAd26-S and rAD5-S vaccine is safe and does not cause serious adverse effects in the healthy volunteers, with no more severe effects than mild common side effects that occur with any vaccine based on a recombinant viral vector.   

-  After vaccination with rAd26 and rAd5, neutralising antibodies, antibodies to defend the cell from SARS-CoV-2, did form, but the levels of neutralising antibodies formed were less than that of the ChAdOx1 vaccine.  However, the rAd26-S and rAD5-S vaccine did elicit the same titre of SARS-CoV-2 neutralising antibodies as did people recovered from COVID-19.  

-  There was a strong humoral immune response in 100% of the volunteers, with equal or higher IgG antibody titres in vaccinated people than those in the convalescent plasma of those already infected with COVID-19, showing the immunogenicity of the vaccine.  

-  There was a strong cellular (T-cell) response to the vaccine, shown from higher rates of CD8+ T cells and increased interferon-y secretion.  

-  Using the rAd26-S for priming and rAd5-S for boosting (this heterologous prime-boost immunisation) effectively elicited an immune response to overcome the immune response that is formed to the viral vector components.  

-  The researchers still need to expand this study to test the vaccine in different populations, including older aged groups and at-risk groups.  


Discussion


Methods of rAd26 and rAd5 Vector-Based Vaccine Phase 1/2 Studies

The phase 1/2 clinical studies evaluating the safety and immunogenicity of the heterologous rAd26 and rAd5 vector-based COVID-19 vaccine reported outcomes across several key areas. These primary results included the evaluation of adverse effects, the cell-mediated (T-cell) immune response to the SARS-CoV-2 glycoprotein, the humoral immune response encompassing RBD-specific IgG and neutralizing antibodies, and the specific neutralizing antibody response to the rAd26 and rAd5 viral vectors.

Learn Before

Related

Learn After