This is a Phase III, parallel-group, prospective, randomized, double-blind, active-controlled, two- arm study to be conducted in approximately 250 participants aged 18 years and above who are generally healthy or with stable pre-existing medical conditions. The participants, investigators, the site personnel and the Sponsor staff who are involved in the blinded conduct of the study will be blinded to the study intervention assignment. Preparation and administration of the study intervention will be performed by authorized unblinded site personnel who do not participate in the evaluation of the participants.~Eligible participants will be randomized to receive either MVC-COV1901 or AZD1222 vaccine in a 1:1 ratio. Randomization of participants will be stratified by study site and age (≥ 18 to < 65 years and ≥ 65 years), at least 40% of the participants shall be ≥ 65 years.~Approximately 30 participants in the age 18 to <65 group and 10 participants in the age ≥ 65 years will be included in the CMI Subset for CMI assessments.
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.