Immunogenicity and Safety Study of SCB-2023 Vaccine as a Booster in Adults

Inclusion Criteria: Male or female ≥18 years of age. Individuals willing and able to comply with study requirements, including all scheduled visits, vaccinations, laboratory tests and other study procedures. Individuals willing and able to give an informed consent, prior to screening. Healthy participants or participants with pre-existing medical conditions who are in a stable medical condition. Individuals who received three doses of inactivated COVID-19 vaccine. Exclusion Criteria: Body temperature >37.8°C (axillary), or any acute illness at baseline. Confirmed SARS-CoV-2 infectionor with known history of COVID-19. Individuals who have received an investigational or licensed COVID-19 vaccine prior to Day 1 (except for inactivated COVID-19 vaccine). Any confirmed or suspected immunosuppressive or immunodeficient condition resulting from disease or immunosuppressive/cytotoxic therapy. Any progressive unstable or uncontrolled clinical conditions. Individuals who are pregnant, or breastfeeding, or planning to become pregnant while enrolled in this study or during the study period. History of severe adverse reaction associated with a vaccine or severe allergic reaction. History of malignancy within 1 year before screening. Individuals who have received any other investigational product. Individuals who have received any other licensed vaccines within 14 days prior to enrollment. Treatment with Rituximab or any other anti-CD20 monoclonal antibodies. Known bleeding disorder that would, in the opinion of the investigator, contraindicate i.m. injection. Administration of intravenous immunoglobulins and/or any blood products. Any condition that, in the opinion of the investigator, would interfere with the primary study objectives or pose additional risk to the participant.