Immuno-bridging Study of COVID-19 Protein Subunit Recombinant Vaccine

This trial is randomized, prospective intervention study. A total of 4,050 subjects (COVID-19 vaccine naive) who are willing to participate in the study by signing the consent form, will be involved in this trial. The subjects will be divided into three study subsets, namely Main Study I, Main Study II, and Exploratory Study: Main Study I for immunogenicity and safety evaluation, Main Study II for safety evaluation, and Exploratory Study for cellular immunity evaluation, with trial design as follow : * Main Study I, Exploratory Study subset: Observer-blind, randomized, active-controlled prospective intervention study * Main Study II: Open-label, randomized study to evaluate safety I