1. Individuals with fever >37.5°C (irrespective of method), or any acute illness at baseline (Day 1) or within 3 days prior to randomization. Participants meeting this criterion may be rescheduled within the relevant window. Afebrile participants with minor illnesses can be enrolled at the discretion of the investigator. 2. Individuals with laboratory-confirmed SARS-CoV-2 infection (as defined by Rapid COVID Antigen Test or an equivalent at Visit 1) or with history of COVID-19. 3. Individuals who have received a prior investigational or authorized or licensed COVID-19 vaccine. 4. Any confirmed or suspected immunosuppressive or immunodeficient condition except HIV infection resulting from disease or immunosuppressive/cytotoxic therapy (e.g., medications used for cancer chemotherapy, organ transplantation or to treat autoimmune disorders) within 6 months prior to enrollment. 5. Individuals who have a history of malignancy within 1 year before screening (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix which have been cured, or other malignancies with minimal risk of recurrence). 6. Individuals with any progressive unstable or uncontrolled clinical conditions. 7. Individuals who are pregnant, or breastfeeding, or planning to become pregnant while enrolled in this study or within 3 months after the last study vaccination. 8. Individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines (CpG/Alum/SCB-2019 components as outlined in the latest IB). 9. Individuals who have received any other investigational product within 30 days prior to Day 1 or intend to participate in another clinical study at any time during the conduct of this study. 10. Individuals who have received any other authorized or licensed vaccines within 14 days prior to enrollment in this study or who are planning to receive any vaccine up to 21 days after the last vaccination. 11. Individuals with known bleeding disorder that would, in the opinion of the investigator, contraindicate intramuscular injection. 12. Individuals who have received treatment with rituximab or any other anti-CD20 monoclonal antibodies within 9 months prior to enrollment or planned during the study period. 13. Individuals who have received intravenous immunoglobulins and/or any blood products within 3 months prior to enrollment or planned administration during the study period. 14. Individuals with any condition that, in the opinion of the investigator, would interfere with the primary study objectives or pose additional participant risk.

1. Individuals with fever >37.5°C (irrespective of method), or any acute illness at baseline (Day 1) or within 3 days prior to randomization. Participants meeting this criterion may be rescheduled within the relevant window. Afebrile participants with minor illnesses can be enrolled at the discretion of the investigator. 2. Individuals with laboratory-confirmed SARS-CoV-2 infection (as defined by Rapid COVID Antigen Test or an equivalent at Visit 1) or with history of COVID-19. 3. Individuals who have received a prior investigational or authorized or licensed COVID-19 vaccine. 4. Any confirmed or suspected immunosuppressive or immunodeficient condition except HIV infection resulting from disease or immunosuppressive/cytotoxic therapy (e.g., medications used for cancer chemotherapy, organ transplantation or to treat autoimmune disorders) within 6 months prior to enrollment. 5. Individuals who have a history of malignancy within 1 year before screening (exceptions are squamous and basal cell carcinomas of the skin and carcinoma in situ of the cervix which have been cured, or other malignancies with minimal risk of recurrence). 6. Individuals with any progressive unstable or uncontrolled clinical conditions. 7. Individuals who are pregnant, or breastfeeding, or planning to become pregnant while enrolled in this study or within 3 months after the last study vaccination. 8. Individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines (CpG/Alum/SCB-2019 components as outlined in the latest IB). 9. Individuals who have received any other investigational product within 30 days prior to Day 1 or intend to participate in another clinical study at any time during the conduct of this study. 10. Individuals who have received any other authorized or licensed vaccines within 14 days prior to enrollment in this study or who are planning to receive any vaccine up to 21 days after the last vaccination. 11. Individuals with known bleeding disorder that would, in the opinion of the investigator, contraindicate intramuscular injection. 12. Individuals who have received treatment with rituximab or any other anti-CD20 monoclonal antibodies within 9 months prior to enrollment or planned during the study period. 13. Individuals who have received intravenous immunoglobulins and/or any blood products within 3 months prior to enrollment or planned administration during the study period. 14. Individuals with any condition that, in the opinion of the investigator, would interfere with the primary study objectives or pose additional participant risk.