A Study to Evaluate Immunogenicity and Safety of MVC-COV1901 Vaccine Compared With AZD1222

The primary objective of the study is to measure the anti-SARS-CoV-2 neutralizing antibody titres in adult participants, in particular elderly, so as to demonstrate immunogenic superiority of MVC-COV1901 to the active control, AZD1222 vaccine, in terms of the GMT of neutralizing antibodies at 14 days after the second dose of the study intervention. This study also assesses the safety and tolerability of the study intervention and explores the immunogenicity in terms of antigen-specific immunoglobulin as well as the potential efficacy of MVC-COV1901 in preventing COVID-19.