A Randomized, Double-blinded, Active-controlled Phase II Clinical Study to Evaluate the Immunogenicity and Safety of SCTV01C (A Bivalent SARS-CoV-2 Trimeric Spike Protein Vaccine) and SCTV01E (A COVID-19 Alpha/Beta/Delta/Omicron Variants S-Trimer Vaccine) in Population Aged ≥12 Years and Previously Unvaccinated is a PHASE2 clinical asset sponsored by Sinocelltech Ltd. in COVID-19, SARS-CoV-2 Infection. SEO and diligence focus: SCTV01C, SCTV01C, SCTV01C, SCTV01E, SCTV01E, SCTV01E, mRNA vaccine manufactured by Pfizer or Moderna, mRNA vaccine manufactured by Pfizer or Moderna, mRNA vaccine manufactured by Pfizer or Moderna, Sinopharm inactivated COVID-19 vaccine, Sinopharm inactivated COVID-19 vaccine, Sinopharm inactivated COVID-19 vaccine, endpoint relevance, enrollment feasibility, competitive positioning, readout timing and IP durability.