An open comparative multicenter prospective study with retrospective data.
An Open Comprative Study of the Prophylactic Efficacy and a Non-comparative Study of the Immunogenicity and Safety of the Inactivated Whole-virion Concentrated Purified Coronavirus Vaccine (CoviVac) Produced by FSBSI Chumakov Federal Scientific Center for Research and Development of Immune-and-Biological Products for Adults Aged 60 Years and Older