Nomor uji klinis NCT04765436 for "PTX-COVID19-B, an mRNA Humoral Vaccine, is Intended for Prevention of COVID-19 in a General Population. This Study is Designed to Evaluate Safety, Tolerability, and Immunogenicity of PTX-COVID19-B Vaccine in Healthy Seronegative Adults Aged 18-64" di ClinicalTrials.gov