The study will be a double-blind placebo-controlled trial with participants randomly allocated 1:1 to placebo and vaccine arms.

The immunization schedule is two doses intramuscular injections (deltoid) with a 14-days interval.

For efficacy, the study aims to detect COVID-19 cases, defined as symptomatic SARS-CoV-2 infections, after the second-week post-immunization schedule.

For safety and immunogenicity, participants are categorized into two age groups, Adults (18-59 years) and Elderly (60 years and above). The safety database aims to detect adverse reactions with a frequency of 1:1000 or higher in adults and 1:500 in the elderly.

All participants will be followed up to 12 months. Interim preliminary efficacy analysis can be triggered by reaching the target number of 61 cases. Primary efficacy analysis requires 151 cases.