2.1. Ethical Approval
The protocol of the CoviVac safety and immunogenicity assessment study in volunteers aged 18–60 years (VKI-I/II-08/20) and its supplementary documentation were approved by the Ethics Committee of the Ministry of Health of the Russian Federation (No. 502 from 21 September 2020). Additionally, the protocol was approved by the local Ethics Committees of the clinical sites, namely Kirov State Medical University of the Ministry of Health of Russia [No. 13/2020 from 28 September 2020]; Healthcare Unit No. 163 of FMBA of Russia, [No.1 from 11 October 2020]; Eco-Safety Scientific Research Center [No. 157 from 1 October 2020]. The study protocol was registered at The protocol of the CoviVac safety and immunogenicity assessment study in volunteers aged 60+ years (VKI-P-II-07/21) and its supplementary documentation were approved by the Ethics Committee of the Ministry of Health of the Russian Federation (No. 288 from 28 September 2021). Additionally, the protocol was approved by the local Ethics Committees of the three clinical sites, namely Mechnikov Research Institute of Vaccines and Sera [No. 483/01 from 3 November 2021], Perm State Medical University [No. 10 from 27 October 2021] and Healthcare Unit No. 163 of FMBA of Russia [No.1 from 28 October 2021]. The study protocol was registered at 