A Study to Investigate the Safety, Immunogenicity of Bivalent mRNA Vaccine RQ3027 and RQ3025 as a Booster Dose in Healthy Adults

Inclusion Criteria: Healthy participants who are determined by medical history, physical examination, and clinical judgment of the investigator to be eligible for inclusion in the study. Participants 18 through 55 years of ages. Participants who have received at least 3 doses COVID-19 vaccine. Participants with the last prior dose being 90 or more days before Visit 1(Day 0) or recovered from COVID-19 at least 28 days. Participants able to comply with all scheduled visits, laboratory tests and investigator's instruction. Exclusion Criteria: Women who are pregnant or breastfeeding. Enrolling in or planning to participate other interventional clinical study. Has received systemic immunoglobulins or blood products within 3 months prior to the day of screening. History of anaphylaxis, urticaria, or other significant adverse reaction requiring medical intervention after receipt of a vaccine. Bleeding disorder considered a contraindication to intramuscular injection or phlebotomy. Continued using anticoagulants such as coumarin and related anticoagulants (i.e., warfarin) or oral anticoagulants (i.e., apixaban, rivaroxaban, dabigatran, and edoxaban). Having coronary heart disease, hypertension, diabetes, chronic respiratory diseases, tumors and poorly controlled. Immunocompromised or having immunosuppressive therapy. Suspected or confirmed alcohol/drug dependence. Investigator decide unsuitable factors for participating in clinical trials in the investigator's judgment