ChulaCov19 Vaccine in Healthy Adults

Participants who meet all the following criteria at Screening are eligible to participate
in the study:

Inclusion criteria:

1. Participants must be able to communicate effectively with study personnel and
considered reliable, willing, and cooperative in terms of compliance with the protocol
requirements.

2. Participants must sign the written informed consent form prior to undertaking any
protocol related procedures.

3. Participants must have a body mass index (BMI) at Screening, calculated as the body
mass divided (in kilograms [kg]) by the square of the body height (in metres [m]) of
18.0-30.0 kg/m2, inclusive.

4. Participants must have haematology, clinical chemistry, coagulation (for all
participants in Phase 1, and, only if applicable, for participants in Phase 2), and
urinalysis test results that are not deviating from the normal reference range by age
and gender to a clinically relevant extent at Screening.

5. Males must be surgically sterile (>30 days since vasectomy with no viable sperm),
practice true abstinence or, if engaged in sexual relations with a female of
child-bearing potential, the participants and their partner must use an acceptable,
highly effective, double-barrier contraceptive method* from Screening and for a period
of at least 60 days after the last dose of investigational vaccine.

6. Women of child-bearing potential must practice true abstinence or, if engaged in
sexual relations with a male, they must agree to use highly effective (failure rate of
< 1% per year when used consistently and correctly), double-barrier contraceptive
measures* throughout the study and intend to continue use of contraception for at
least 60 days following the last vaccination.

* The PI is to assess the adequacy of methods of contraception on a case-by-case
basis. These criteria do not apply if the participants are in a same-sex relationship.

7. Women of child-bearing potential must have a negative serum pregnancy test (beta human
chorionic gonadotropin [β-HCG]) at Screening and a negative urine-based test within 24
hours prior to each investigational vaccine administration.

8. Women of non-child-bearing potential must:

1. be classified as being postmenopausal (defined as having a history of amenorrhea
of at least one year), or

2. where history of amenorrhea is less than one year, female participants must have
a follicle stimulating hormone (FSH) level > 40 milli-international units per
milliliter (mIU/mL), or

3. have a documented status of being surgically sterile (hysterectomy, bilateral
oophorectomy, or tubal ligation/salpingectomy).

9. Participants must be in general good health based on medical history and physical
examination, as determined by the PI, at Screening.

10. Body temperature must be less than 37.8ºC, at Screening.

11. Pulse must be no greater than 100 beats per minute, at Screening.

12. Systolic blood pressure (SBP) must be between 85 to 150 millimetres of mercury (mm
Hg), inclusive, at Screening.

13. Participants must agree to refrain from donating blood, plasma, ovules, sperm, or
organs during the whole study.

Adult Participants (Group 1 of Phase 1) only

14. Must be a male or female aged 18-55 years (inclusive) at the time of enrolment.

Elderly Participants (Group 2 of Phase 1) only

15. Must be a male or female aged 56-75 years (inclusive) at the time of enrolment.

Participants for Phase 2 only

16. Must be a male or female aged 18 -59 years (inclusive) at the time of enrolment.

Exclusion Criteria

The presence of any of the following criteria will constitute cause for the exclusion of
the participant:

1. Presence of clinically significant medical history, unstable chronic or acute disease,
or physical, or laboratory findings that, in the opinion of the PI may potentially
increase the expected risk of exposure to the investigational vaccine, compromise the
safety of the participant, or interfere with any aspect of study conduct or
interpretation of results. This will include asthma and any thrombocytopenia or
bleeding disorder contraindicating IM vaccination.

2. Presence of self-reported or medically documented significant medical or psychiatric
condition(s).

3. Presence of an acute illness, as determined by the participating site PI or
appropriate sub-PI, with or without fever (temperature ≥ 38.0 ºC) within 72 hours
prior to each vaccination.

4. Presence of birthmarks, tattoos, wound, or other skin conditions over the deltoid
region of both arms that, in the PI's opinion, could reasonably obscure and interfere
with evaluation of local ISRs.

5. Inadequate venous access to allow collection of blood samples.

6. Breastfeeding or planning to breastfeed from the time of the first vaccination through
60 days after the last vaccination, or pregnant as confirmed by a positive serum β-HCG
pregnancy test at Screening or positive urine pregnancy test at subsequent clinic
visits at timepoints as delineated in the schedule of assessments.

7. Received any prophylactic or therapeutic vaccine, or licensed or unlicensed vaccine,
drug, biologic, device, blood product, or medication, within 4 weeks of first
vaccination or 5 half-lives (whichever is longer), or anticipate to do so in the
follow-up period defined for this study.

8. Participant has previously participated in an investigational study involving LNPs (a
component of the investigational vaccine assessed in this trial).

9. History of severe allergy (requiring hospital care), severe reaction to any drug or
prior vaccination, or any known or suspected allergies or sensitivities to any
component of the investigational vaccine or placebo.

10. History of ever had an anaphylaxis reaction to food, medication or vaccination.

11. Participant is immunosuppressed as caused by disease (such as HIV).

12. Chronic use (more than 14 continuous days) of or anticipated need to use, within the
next 6 months, of any medications that may be associated with impaired immune
responsiveness or with immunosuppression.

13. History of hepatitis B or hepatitis C infection.

14. Receipt of immunoglobulins or blood products within 3 months of first vaccination.

15. Requirement for antipyretic or analgesic medication on a daily or every other day
basis from enrolment through 72 hours after vaccination.

16. Current use of any prescription or over-the-counter medications within 7 days prior to
vaccination, unless approved by the PI.

17. History of alcohol or drug abuse that in the opinion of the PI could affect the
participant's safety or compliance with study.

18. Participant unwilling to abstain from blood donation during the course of the study,
and/or participation in any research study involving blood sampling (more than 450 mL
/unit of blood), or blood donation to any blood bank during the 2 months prior to the
Screening visit.

19. Close contact with anyone known to have SARS-CoV-2 infection within 30 days prior to
vaccine administration.

20. Positive for SAR-CoV-2 by antibody IgG/IgM and anti spike IgG at screening

21. History of COVID-19 diagnosis (the criteria for COVID-19 diagnosis will follow the
local guidelines).

22. On current treatment with investigational agents for prophylaxis of COVID-19.

23. Planning to travel outside Thailand from enrolment through 28 days after the second
vaccination.

24. Residing in a nursing home or other skilled nursing facility or having a requirement
for skilled nursing care.

25. Is a participant at high risk of SARS-CoV2 exposure in the opinion of the PI (e.g.,
healthcare workers, active health care workers with direct patient contact, emergency
response personnel).

Elderly Participants (Group 2 of Phase 1) only

26. Chronically smoking (defined as ≥10 Pack years [packs/day × years smoked]) within the
12 months prior to enrolment.

27. Presence of co-morbidities that can be associated with an increased risk of severe
COVID-19 Cancer, Chronic kidney diseases, COPD, cardiovascular disease, solid organ
transplantation, DM type 2, HT, cerebrovascular disease, Obesity (BMI> 30 kg/m2)

Participants for Phase 2 only

28. Presence of co-morbidities that can be associated with an increased risk of severe
COVID-19 Cancer, Chronic kidney diseases, COPD, cardiovascular disease, solid organ
transplantation, DM type 2, uncontrolled HT, cerebrovascular disease