Exploratory Clinical Study to Evaluation of the Safety and Immunogenicity of Bivalent Vaccine V-01D-351

Inclusion Criteria: * Adults aged 18 years and older at time of consent, male or female; * Normal body temperature; * Meet either of the following conditions: 1. Received completed primary immunization of 2 doses of CoronaVac 6-15 months ago; 2. Received completed 3 doses of CoronaVac 5-9 months ago; * Female participants who are not pregnant at the time of enrollment (urine pregnancy test is negative), nor during lactating; and has no birth plan and agree to take effective contraception in 7 months after enrollment; and took effective and acceptable contraceptive methods in the previous 2 weeks before the enrollment; * Be able and willing to complete the study during the entire study and follow-up period; * Participants who have the ability to understand the study process, sign the informed consent form voluntarily , and be able to comply with the requirements of the clinical study protocol. Exclusion Criteria: * Serious chronic diseases or uncontrolled diseases; * Uncontrolled neurological disorders, epilepsy; * Received any inactivated vaccine within 1 week or received any attenuated vaccines within 4 weeks; * Patients with congenital or acquired immunodeficiency; * History of severe allergy or be allergic to any components of the test vaccines; * History of hereditary hemorrhagic tendency or coagulation dysfunction; * Patients with malignant tumors and other patients have a life expectancy less than 1 year; * Refuse to sign the informed consent form or inability to complete follow-ups as required by the protocol; * History of previous COVID-19 infection; * Pregnant or breastfeeding women, or females of childbearing potential who not agree to or able to take effective and acceptable contraceptive methods during the study; * Participants who have participated in other clinical trials within 3 months or are participating in other clinical trials; * Those considered by the investigator as inappropriate to participate in the study.