Introduction
RBD
CORONAVIRUS, ADENOVIRUS, SEVERE ACUTE RESPIRATORY SYNDROME, FLU
The ongoing COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in morbidity and mortality unseen since the Spanish flu outbreak more than a century ago [A candidate COVID-19 vaccine that initially showed a capacity to induce a significant antibody and cellular immune response is the adenovirus type 5 (Ad5)-nCoV vaccine developed by CanSino Biologics Inc., Tianjin, and the Beijing Institute of Biotechnology, People’s Republic of China. It consists of a replication-defective Ad5 vector expressing the SARS-CoV-2 spike (S) protein, including its receptor-binding domain (RBD). This protein serves as the main antigen in SARS-CoV-2 vaccines [A collaborative development project between CanSino Biologics and the Russian pharmaceutical company NPO Petrovax Pharm LLC provided the basis for a new phase 3 study, Prometheus Rus, which is the clinical protocol code that was approved by a local authority. This multicentre, randomised, double-blind, placebo-controlled clinical trial examines the immunogenicity, reactogenicity, efficacy and safety of the Ad5-nCoV COVID-19 vaccine compared with placebo, in a mostly white, Russian population. The study population was recruited at centres in the western part of the Russian federation (Moscow, St. Petersburg and Yaroslavl) and therefore provides the first clinical data available for Ad5-nCoV in a white European population; previously published data were based on the phase 1 and 2 clinical trials conducted in China. We present the final analysis of the 496 participants in this phase 3 trial.