Immunogenicity, Efficacy and Safety Trial of the Convacell Vaccine in Healthy Volunteers Aged 18 Years and Older

The goal of this clinical trial is to assess the immunogenicity, efficacy and safety of the Convacell vaccine in healthy adult volunteers aged 18 years and older. The main questions it aims to answer are: * To assess the immunogenicity and safety of single and double dose intramuscular administration of the Convacell vaccine; * To assess the epidemiological effectiveness of the Convacell vaccine in the prevention of SARS-CoV-2 infection and development of severe COVID-19 compared with placebo when single or double intramuscular injection.