Inclusion Criteria:

1. Male or female ≥18 years of age.

2. Individuals are willing and able to comply with study requirements, including all
scheduled visits, vaccinations, laboratory tests and other study procedures.

3. Individuals are willing and able to give an informed consent, prior to screening.

4. Healthy participants or participants with pre-existing medical conditions who are in
a stable medical condition. (A stable medical condition is defined as medication not
requiring major change for specific past medical condition, not receive surgery or
minimal invasive medical intervention, and without hospitalization or ER visit
during the 3 months before enrollment.)

5. Female participants of childbearing potential may be enrolled in the study, if the
participant has practiced adequate contraception for 30 days prior to vaccination,
and has a negative pregnancy test on the day of vaccination and has agreed to
continue adequate contraception for 6 months after the last vaccination.

6. Male participants must agree to employ acceptable contraception from the day of the
first dose of the study vaccine/placebo until 6 months after the last dose of the
study vaccine/placebo and also refrain from donating sperm during this period.

Exclusion Criteria:

1. Individuals with fever >37.3°C (axillary), 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. Febrile 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 reverse
transcriptase polymerase chain reaction (RT-PCR) assay or Rapid COVID-19 Antigen
Test or an equivalent at Visit 1] or with history of COVID-19, or individual with
COVID-19 pandemic area contaction confirmed with inspection or health code on
cellphone.

3. Individuals who have received an investigational or authorized COVID-19 vaccine
prior to Day 1, or plan to receive COVID-19 vaccine during the study period.

4. Any confirmed or suspected immunosuppressive or immunodeficient condition resulting
from disease [e.g., malignancy, human immunodeficiency virus (HIV) infection] or
immunosuppressive/cytotoxic therapy (e.g., systemic corticosteroids, medications
used for cancer chemotherapy, organ transplantation or to treat autoimmune
disorders) within 3 months prior to Day 1.

5. Individuals with any progressive unstable or uncontrolled clinical conditions.

6. Individuals who are pregnant, or breastfeeding, or planning to become pregnant while
enrolled in this study or during the study period.

7. 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 1018, aluminum), or SCB-2019 components as outlined in the latest IB].

8. 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).

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 licensed vaccines within 14 days prior to
enrollment in this study or who are planning to receive any vaccine up to Day 53.

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 Day 1 or planned during the study
period.

13. Administration of 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 risk to the
participant.