You are being invited to take part voluntarily in a research study because you are a healthcare worker who is at high risk of being infected with SARS-CoV-2 (COVID19) virus. In these trials, we want to evaluate the safety, immunogenicity, and efficacy of several vaccines against test-documented, symptomatic COVID-19 disease among health-care workers in Saudi Arabia.

Inclusion criteria

1. Adults ≥ 18 years of age
2. Health care workers Able to comply with all the study procedures, signed the informed consent form.*Definition of Health Care workers: People engaged in the care of the patients and in direct contact with the patient or the patient’s surrounding and may include the following occupations (not inclusive list): Physician, Nurse, Pharmacist, Respiratory Therapist, Housekeepers, Physiotherapist, Occupational Therapist, Laboratory Technician, Midwifery, Radiology Technicians who are involved directly in patient care (e.g.Ultrasound Technicians, Intervention radiology Technicians), Operating Theater technicians, Intervention radiologist, Unit attendant who is in direct encounter with the patient (e.g. Case managers, Unit assistants, etc…),Social workers, Paramedics and allied medical personnel, Psychologist and Psychiatrist, Dietician and ny other occupation which fulfil the above-mentioned definition

Exclusion criteria

1. For females: Pregnancy (confirmed by positive beta-hCG test), breastfeeding or intent to engage in sexual relations with reproductive intent without use of birth control methods in the three months following vaccination.
2. Known allergy to components of the study vaccine or control.
3. Use of immunosuppressant therapy regimens within the six months prior to enrollment in the study or planned use within the two years following enrollment. Immunosuppressant therapy regimens include: antineoplastic chemotherapy, radiation therapy and immunosuppressants to induce transplant tolerance, among others.
4. Use of immunosuppressive doses of corticosteroids within the three months prior to the enrollment in the study and planned use of immunosuppressive doses of corticoids within the three months following enrollment in the study. Immunosuppressive doses of corticosteroids will be considered the equivalent prednisone 20 mg/day for adults, for longer than one week. Continued use of topical or nasal corticosteroids is not considered an immunosuppressant.
5. History of asplenia.
6. History of bleeding disorder (e.g. factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venepuncture.
7. Any alcohol or drug abuse over the 12 months prior to enrollment in the study that has caused medical, professional or family problems, indicated by clinical history.
8. Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate.
9. Participation in another clinical trial with an investigational product in the six months prior to enrollment in the study or planned participation in another clinical trial within the two years following enrollment.
10. Received live attenuated virus vaccine or inactivated vaccine within the 28 days or 14 days, respectively, prior to enrollment in the study.
11. Fever (axillary temperature >37.5℃) within the past 24 hours.
12. Any other condition that, in the opinion of the principal investigator (PI) or his/her representative physician, could put the safety/rights of potential participants at risk or prevent them from complying with this protocol.